Methods of Earth Resistance Testing (Part-2)


Can we use an Megger or Multimeter for earth resistivity Testing

  • We cannot use Megger or Mulitimeter for Earth resistivity Testing.

Insulation Tester (Megger):

  • Insulation testers are designed to measure at the opposite end of the resistance by inserting high DC Voltage.
  • Insulation testers use high test voltages in the kilovolt range. The area between electrode and ground is charged with high DC Voltage and we do not want grounds that measure in megohms.
  • Ground testers use Low Voltage for testing for operator safety, to low voltages.

Multimeter:

  • However, a Multimeter or continuity test can use very low Voltage between an installed electrode and a reference ground, which is assumed to have negligible.
  • Low voltage DC can produce a resistance reading between ground and an earth electrode but it is not an accurate measurement.
  • Multimeter measurement may not be reliable, since reading can be influenced by soil transients, the electrical noise that is generated by utility ground currents trying to get back to the transformer, as well as other sources.

Can Earth resistance reduce by pouring Water around Test Earth Probe

  • By pouring water is near test probe reduce contact resistance of between probe and ground at some extent.
  • If there is sufficient contact between probe and ground then pouring water near test probe is never decrease earth resistance of the system.
  • Earth resistance is the resistance of the ground electrode that is being measured, not that of the test probe. The Test probe is a tool to use measurement of earth resistance.
  • If the test setup has adequate spacing, the probes will be far enough away outside of the electrical field of the test ground so that watering them has no influence on the test result.

 Test Methods for Measuring Earth Resistance

There are six basic test methods to measure earth resistance

  1. Four Point Method (Wenner Method)
  2. Three-terminal Method (Fall-of-potential Method / 68.1 % Method))
  3. Two-point Method (Dead Earth Method)
  4. Clamp-on test method
  5. Slope Method
  6. Star-Delta Method

 

 (1) Four Point Method (Wenner Method):

  • This method is the most commonly used for measuring soil resistivity,

Required Equipments:

  • Earth Tester (4 Terminal)
  • 4 No’s of Electrodes (Spike)
  • 4 No’s of Insulated Wires
  • Hammer
  • Measuring Tap

Connections:

  • First, isolate the grounding electrode under measurement by disconnecting it from the rest of the system.
  • Earth tester set has four terminals, two current terminals marked C1 and C2 and two potential terminals marked P1 and P2.
  • P1 = Green lead, C1 = Black lead, P2 = Yellow lead, C2 = Red lead
  • In this method, four small-sized electrodes are driven into the soil at the same depth and equal distance from one another in a straight line.
  • The distance between earth electrodes should be at least 20 times greater than the electrode depth in ground.
  • Example, if the depth of each earth electrode is 1 foot then the distance between electrodes is greater than 20 feet.
  • The earth electrode under measurement is connected to C1 Terminal of Earth Tester.
  • Drive another potential Earth terminal (P1) at depth of 6 to 12 inches from some distance at C1 Earth Electrode and connect to P1 Terminal of Earth Tester by insulted wire.
  • Drive another potential Earth terminal (P2) at depth of 6 to 12 inches from some distance at P1 Earth Electrode and connect to P2 Terminal of Earth Tester by insulted wire.
  • Drive another Current Electrode (C2) at depth of 6 to 12 inches from some distance at P2 Earth Electrode and connect to C2 Terminal of Earth Tester by insulted wire.
  • Connect the ground tester as shown in the picture.

Testing Procedure:

  • Press START and read out the resistance value. This is the actual value of the ground Resistance of the electrode under test.
  • Record the reading on the Field Sheet at the appropriate location. If the reading is not stable or displays an error indication, double check the connections. For some meters, the RANGE and TEST CURRENT settings may be changed until a combination that provides a stable reading without error indications is reached.
  • The Earthing Tester has basically Constant Current generator which injects current into the earth between the two current terminals C1 (E) and C2 (H).
  • The potential probes P1 & P2 detect the voltage ΔV (a function of the resistance) due to the current injected in the earth by the current terminals C1 & C2.
  • The test set measures both the current and the voltage and internally calculates and then displays the resistance. R=V/I
  • If this ground electrode is in parallel or series with other ground rods, the resistance value is the total value of all resistances.
  • Ground resistance measurements are often corrupted by the existence of ground currents and their harmonics. To prevent this it is advisable to use Automatic Frequency Control (AFC) System. This automatically selects the testing frequency with the least amount of noise enabling you to get a clear reading.
  • Repeat above steps by increasing spacing between each electrode at equal distance and measure earth resistance value.
  • Average the all readings
  • An effective way of decreasing the electrode resistance to ground is by pouring water around it. The addition of moisture is insignificant for the reading; it will only achieve a better electrical connection and will not influence the overall results. Also a longer probe or multiple probes (within a short distance) may help.

Application:

  • It is advisable for Medium or Large electrode System.
  • It is use for Multiple Depth Testing

Advantage:

  • This is most accurate Method.
  • It is Quick, easy method.
  • Extremely reliable conforms to IEEE 81;

Disadvantage:

  • There need to turn off the equipment power or disconnect the earth electrode.
  • One major drawback to this method is that it requires a large distance for measurement.
  • This distance can range up to 2,000 feet or more for ground systems covering a large area or of very low resistance.
  • Time consuming and labor intensive

 

2) Three Point (Fall-of-potential) Method.

  • The Fall-of-Potential method or Three-Terminal method  is the most common way to measure earth electrode system resistance, but it requires special procedures when used to measure large electrode systems
  • There are three basic fall-of-potential test method.
  • Full fall-of-Potential: A number of tests are made at different spaces of Potential Probe “P” and the resistance curve is plotted.
  • Simplified Fall-of-Potential: Three measurements are made at defined distance of Potential Probe ”P” and mathematical calculations are used to determine the resistance.
  • 8% Rule: A single measurement is made with Potential Probe “P” at a distance 61.8% (62%) of the distance between the electrode under test and “C”.

Required Equipment:

  • Earth Tester (4 Terminal or 3 Terminal)
  • 4 No’s of Electrodes (Spike)
  • 4 No’s of Insulated Wires
  • Hammer
  • Measuring Tap

Connections:

  • First, isolate the grounding electrode under measurement by disconnecting it from the rest of the system.
  • For Small System:
  • For 4 Terminal Earth Tester Short Current Terminal (C1) and Potential Terminal (P1) together with a short jumper on the earth tester and connect it to earthing electrode under test.
  • For 3 Terminal Earth Tester Connect current terminal (C1) to the earth electrode under measurement.
  • Drive another Current Electrode (C2) into the earth 100 to 200 feet at depth of 6 to 12 inches from the center of the electrode and connect to C2 Terminal of earth tester.
  • Drive another potential terminal (P2) at depth of 6 to 12 inches into the earth midway between the Current Electrode (C1) and Current Electrode (C2) and connect to Earth Tester on P2
  • For Large System
  • Place the current electrode (C2) 400 to 600 feet from the measuring Earth Current Electrode (C1)
  • Place the potential electrode (P1)8% of the distance from the Earth Current Electrode (C1)
  • Measure the resistance
  • Move the current electrode (C2) farther 50 to 100 Feet away from its present position.
  • Place the potential electrode (P2) 61.8% of the distance from the Earth Current Electrode (C1).
  • Spike length in the earth should not be more than 1/20th distance between two spikes.

Testing Procedure:

  • Press START and read out the resistance value. This is the actual value of the ground electrode under test.
  • Move the potential electrode 10 feet farther away from the electrode and make a second Measurement.
  • Move the potential probe 10 feet closer to the electrode and make a third measurement.
  • If the three measurements agree with each other within a few percent of their average, then the average of the three measurements may be used as the electrode resistance.
  • If the three measurements disagree by more than a few percent from their average, then additional measurement procedures are required.
  • The electrode center location seldom is known. In this case, at least three sets of measurements are made, each with the current probe a different distance from the electrode, preferably in different directions.
  • When space is not available and it prevent measurements in different directions, suitable measurements can be made by moving the current probe in a line away from or closer to the electrode.
  • For example, the measurement may be made with the current probe located 200, 300 and 400 feet along a line from the electrode.
  • Each set of measurements involves placing the current probe and then moving the potential probe in 10 feet increments toward or away from the electrode.
  • The starting point is not critical but should be 20 to 30 feet from the electrode connection point, in which case the potential probe is moved in 10 feet increments toward the current probe, or 20 to 30 feet from the current probe, in which case the potential probe is moved in 10 feet increments back toward the electrode.
  • The spacing between successive potential probe locations is not particularly critical, and does not have to be 10 feet, as long as the measurements are taken at equal intervals along a line between the electrode connection and the current probe.
  • Larger spacing means quicker measurements with fewer data points. smaller spacing means more data points with slower measurements.
  • Once all measurements have been made, the data is plotted with the distance from the electrode on the horizontal scale and the measured resistance on the vertical scale.

Importance of Position of Current Electrode (C2):

  • Fall-of-Potential measurements are based on the distance of the current and potential probes from the center of the electrode under test.
  • For highest degree of accuracy, it is necessary that the probe is placed outside the sphere of influence of the ground electrode under test and the auxiliary earth.
  • If we Place Current Electrode (C2) too near to Earth Electrode (C1) then the sphere of influence, the effective areas of resistance will overlap and invalidate measurements taken.
  • For the accurate results and to ensure that the ground stakes are outside the spheres of influence.
  • Reposition the inner Potation Electrode (P1) 1meter in either direction and take a fresh measurement. If there is a significant change in the reading (30 %), we need to increase the distance between the ground rod under test, the inner stake (probe) and the outer stake (auxiliary ground) until the measured values remain fairly constant when repositioning the inner stake (probe).
  • The best distance for the current probe is at least 10 to 20 times the largest dimension of the electrode.
  • Because measurement results are often distorted by underground pieces of metal, underground aquifers, etc so re measurements are done by changing axis of earth spike by 90 degrees, by changing the depth and distance several times, these results can be a suitable ground resistance system.
  • The table is a guide for appropriately setting the probe (inner stake) and auxiliary ground (outer stake).

Distance of  Probe

Depth of the ground electrode Distance to the
inner stake
Distance to the
outer stake
2 m 15 m 25 m
3 m 20 m 30 m
6 m 25 m 40 m
10 m 30 m 50 m

Application:

  • It is advisable for High Electrical Load.
  • It is suitable for small and medium electrodes system (1 or 2 rods/plates). .
  • It is useful for homogeneous Soil

Advantage:

  • The three-point method is the most reliable test method;
  • This test is the most suitable test for large grounding systems.
  • Three-terminal is the quicker and simpler, with one less lead to string Spacing For Current Probe

Disadvantage:

  • Individual ground electrodes must be disconnected from the system to be measured.
  • It is extremely time consuming and labor intensive.
  • There are situations where disconnection is not possible.
  • Knowledge of location of center probe is necessary
  • Time consuming and labor intensive Ineffective if the electrical center is unknown.
  • If less measurements are being made then less accurate than full Fall of Potential

 

61.8% Rule:

  • It is proven that the actual electrode resistance is measured when the potential probe is located 61.8% of the distance between the center of the electrode and the current probe. For example, if the current probe is located 400 feet from the electrode center, then the resistance can be measured with the potential probe located 61.8% x 400 = 247 feet from the electrode center.
  • The 61.8% measurement point assumes the current and potential probes are located in a straight line and the soil is homogeneous (same type of soil surrounding the electrode area and to a depth equal to 10 times the largest electrode dimension).
  • The 61.8% measurement point still provides suitable accuracy for most measurements.

  • Suppose, the distance of Current Spike from Earth Electrode D = 60 ft, Then, distance of Potential Spike would be 62 % of D = 0.62D i.e.  0.62 x 60 ft = 37 ft.

Application:

  • It is suitable for small and medium electrodes system.
  • It is useful for homogeneous Soil

Advantage:

  • Simplest to carry out.
  • Required minimum calculation;
  • Fewest number of test probe moves.

Disadvantage:

  • Soil must be homogeneous.
  • Less accurate
  • Susceptible for non-homogeneous soil

Methods of Earth Resistance Testing (Part-1)


Introduction:

  • The measurement of ground / Earth resistance for an earth electrode is very important for not only for human safety but also for preventing damages of equipment, industrial plants and to reduce system downtime.
  • It also provides protection against natural phenomenon such as lightning stock by providing path to the lightning current to the ground.
  • Ground resistance is the measurement of the resistance between conducting connection and earth Soil.
  • Earth Resistance should be Low as possible to provide low resistance path to leakage current to the earth.
  • Ground resistance depends on grounding electrode selection, soil resistivity, soil contact, and other factors

 Difference between Ground Resistance and Ground Resistivity

  •  Ground / Earth Resistance:
  • Ground Resistance is the resistance (Which oppose of current flow) of an installed earthing electrode system.
  • It is the resistance between a buried electrode and the surrounding soil.
  • It is measured in
  • Ground Resistance is measured with a four-point, three-point or clamp on tester.
  • Ground / Earth Resistivity:
  • Ground resistivity is a measurement of how much the soil resists the flow of electricity.
  • Ground resistivity is the electrical properties of the soil for conducting current.
  • It indicates how good the soil /Earth conducts electric currents. For the lower the resistivity, the lower the earth electrode resistance at that location.
  • Ground resistivity is theoretical resistance of a cylinder of earth Piece having a cross-section area of 1 Sq. meter.
  • Ground resistivity (ρ)is measured in Ohm centimeters.
  • Ground resistivity has nothing to deal with any installed electrical structure, but is a pure measurement of the electrical conductivity of the soil itself.
  • Ground resistivity is measured with a four-point tester.
  • Ground resistivity varies significantly according to the region, season and the type of soil because it depends on the level of humidity and the temperature (frost or drought increase it).

Purpose of Measurement of Earth Resistivity:

  • Earth resistivity measurements have a Main three purpose.
  • Earth resistivity data is used to use survey for Surface of Land to identifying locations, depth to bedrock and other geological phe­nomena.
  • Earth resistivity data is used for protective anticorrosion treatment of underground pipelines, because Earth resistivity is direct related on the degree of corro­sion of underground pipelines. Lower in resistivity increase in corrosion of Underground Pipes.
  • Earth resistivity directly affects the design of an Earthing system. When we design an Earthing system, it is advisable to locate the area of lowest soil resistivity to achieve the most economical grounding installation. If the lower the soil resistivity value, the lower the grounding electrode resistance.

Earth Resistivity depends on:

  • There are various that affect the ground resistance of a ground system

(1)  Diameter of Ground Rod:

  • Increasing the diameter of the ground electrode has very little effect in lowering the resistance.
  • Doubling diameter of ground rod reduces resistance only 10%.
  • Using larger diameter ground rods is mainly a strength issue. In rocky conditions, a larger diameter ground rod might be advantageous.

(2) Depth of Ground Rod:

  • As per NEC code minimum ground electrode length of 2.5 meters (8.0 feet) to be in contact with the soil.
  • Doubling depth of Rod theoretically reduces resistance 40%.
  • Earthing Spike (electrodes) deeper is a very effective way to lower Earthing resistance.
  • Actual reduction of resistance depends on soil resistivity encountered in multi-layered soils.
  • The resistance decreases rapidly as the length of the electrode increases and less rapidly as the diameter increases.

(3) Spacing of Ground Rod:

  • Earth resistance decrease when distance between adjustments earthing Rod is twice the length of the rod in Ground (in good soil).

t

Probe Spacing
Probe distance (m) Soil resistance, Re (Ω) Soil resistivity, ρρ (Ω m)
0.3 14.75 27.79
0.6 7.93 29.88
0.9 6.37 36.00
1.2 4.36 32.86
1.5 4.31 40.60

(4) No of Ground Rods:

  • Using multiple ground electrodes provides another way to lower ground resistance.
  • More than one electrode is driven into the ground and connected in parallel to lower the resistance.
  • The spacing of additional rods must be at least equal to the depth of the driven rod.
  • Two well-spaced rods driven into the earth provide parallel paths and act as two resistances in parallel. However the rule for two resistances in parallel does not apply exactly so the resultant resistance is not one-half the individual rod resistances.
  • The reduction in Earth resistance for equal resistance rods is
  • 40 % for 2 rods
  • 60 % for 3 rods
  • 66 % for 4 rods

(5) Material & Surface Condition of Ground Rod:

  • Grounding electrodes are usually made of a very conductive metal (stainless steel, copper or copper clad) with adequate cross sections so that the overall resistance is negligible.
  • The resistance between the electrode and the surrounding earth is eligible if the electrode is not free of paint, grease, or other coating, and not firmly packed with earth.
  • If the electrode is free from paint or grease, and the earth is packed firmly, contact resistance is negligible.
  • Rust on an iron electrode has little or no effect .But if an iron pipe has rusted through, the part below the break is not effective as a part of the earth electrode

(6) Moisture

  • Low-resistivity soils are highly influenced by the presence of moisture.
  • The amount of moisture and salt content of soil affects its resistivity.
  • Actually, pure water has an infinitely high resistivity. Naturally occurring salts in the earth, dissolved in water, lower the resistivity. Only a small amount of salt can reduce earth resistivity quite a bit.

(7) Temperature

  • Increase in temperature will decrease resistivity
  • Increase in temperature markedly decreases the resistivity of water.
  • When water in the soil freezes, the resistivity jumps appreciably; ice has a high resistivity. The resistivity continues to increase a temperatures go below freezing.

(8) Soil type

  • Some soils such as sandy soils have high resistivity that conventional ground.
  • Frozen and very dry soils are good insulators and have high resistivity.
  • In low resistivity soils, the corrosion rate is often greater than in high resistivity soils
  • The resistivity is much lower below the subsoil water level than above it. In frozen soil, as in a surface layer in winter, it is particularly high.

(9) Choosing Proper Instrument:

  • Use a dedicated ground tester for measuring earth resistance.
  • Do not use a generalized ohmmeter, multi meter or Megger for that.
Soil Resistivity (approximate ohm-meters)
Soil Description Minimum Median Maximum
Topsoil, loam 1 26 50
Inorganic clays of high plasticity 10 33 55
Fills – ashes, cinders, brine wastes 6 38 70
Gravelly clays, sandy clays, silty clays, lean clays 25 43 60
Slates, shale 10 55 100
Silty or clayey fine sands with slight plasticity 30 55 80
Clayey sands, poorly graded sand-clay mixtures 50 125 200
Fine sandy or silty clays, lean clays 80 190 300
Decomposed gneisses 50 275 500
Silty sands, poorly graded sand-silt mixtures 100 300 500
Clayey gravel, poorly graded gravel, sand-clay mixture 200 300 400
Well graded gravel, gravel-sand mixtures 600 800 1000
Granites, basalts, etc. 1000
Sandstone 20 1010 2000
Poorly graded gravel, gravel-sand mixtures 1000 1750 2500
Gravel, sand, stones, little clay or loam 590 2585 4580
Surface limestone 100 5050 10000

  

Soil Resistivity Ranges
1000 Ohm cm Wet organic soil
10000 Ohm cm Moist soil
100000  Ohm cm Dry soil
1000000 Ohm cm Bed rock
590 to 7000 Ohm cm Ashes, cinders, brine, waste
340 to 1630 Ohm cm Clay, Shale, Loam
59000 to 458000 Ohm cm Gravel , Sand , Stone with little Clay
300 to 500 Ohm meter Concrete
900 to 1100 Ohm meter Granite
20 to 2000 Ohm meter Sand Stone
100 – 15,000 Ohm cm Standard Design OK
15,000- 25,000 Ohm cm Standard Design Maybe
25,000 – 50,000 Ohm cm Special – Contact the carrier, owner or engineering

firm

50,000 + Ohm cm Very Special – Perhaps not practical

 

Ground Resistance Values
Industrial plant: 5 Ω
Chemical plant: 3 Ω
Computer System 3 Ω
Lighting Protection 1 Ω
Generating station: 1 Ω
Large HV sub-station, Generating Station (IEEE Std 142 clause 4.1.2) 1 Ω
Small Distribution sub-station (IEEE Std 142 clause 4.1.2) 5 Ω
Telecommunication facilities <5Ω
Water pipe ground should <3Ω

Method for Installation of Earthing Strip


(A) Purpose:

  • The method is to explain the procedure, which should be followed to install the Earthing Strip, Earthing Wire, and Earthing accessories as per the specification to achieve the standard requirements of the project.

(B) Equipment & Tools:

  • The equipment that will be used for Installation of Earthing Strip / Wire works are
  1. Ladder
  2. Spirit Level
  3. Drilling Machine
  4. Grinding Machine
  5. Cutting Machine
  6. Power tools
  7. Measure Tape
  8. Screwdriver
  9. Drill with bits
  10. File
  11. Galvanizing paint
  12. Bitumius Paint

(C) Test for Earthing Strip / Earthing Accessories:

  • Visual inspection:
  • Type of Earthing Strip and Accessories Material
  • Length , Width and thickness of Earthing Strip and Accessories
  • Galvanization thickness
  • Galvanization tests to be conduct.
  • Proper painting / Galvanization and identification numbers of the Earthing Strip and Accessories
  • The GS Flat to be supplied in 5.5 meters to 13 meters lengths.
  • The weight of GS Flat
  • MS flat shall conform to IS 2062 & its latest amendments for steel & Galvanization as per IS 4759 & its Latest amendments
  • Physical Damages Inspection:
  • Damage on Earthing Strip and Accessories
  • Damage on galvanizing
  • Testing of galvanizing:
  • Uniformity of coating Thickness Test
  • TRs not more than five year old shall be reviewed for acceptance.
Hot dip galvanization. (IS 2629)
Galvanizing Minimum thickness: Min. weight:
MS flats 5mm thick & over 75 microns (minimum) 610 gms. / sq. mtr.
MS flats under 5mm thickness 60 microns (minimum) 460 gms. / sq. mtr.
Pipes/ conduits with thickness over 5 mm 75 microns (minimum) 610 gms. / sq. mtr
Pipes/ conduits with thickness under 5mm 60 microns (minimum) 460 gms. / sq. mtr
GI Wire 20 Microns (Medium coated) 150 gms. / sq. mtr.

(D) Storage & Handling:

  • The Earthing Flat shall be supplied in standard lengths.
  • Materials should be stored according to a specification which is the maximum 1.5m height from the ground. Suitable support should be provided. The storage should be done in a designated area and proper covering should be provided.
  • Earthing Strip and Accessories (pre-galvanized, hot dipped galvanized) shall be stored in a dry place, fully enclosed / ventilated store.
  • When bringing down materials, they should be handled with care and lowered carefully to the ground. They should not be dropped.

(E) Preparation for Earthing Strip / Wire

  • Check and ensure that the correct size and type of Earthing Strip & accessories are ready for installation.
  • Ensure that the work area is ready and safe to start the installation of Earthing Strip.
  • Ensure that Earthing Strip and accessories received from site store for the installation are free of rusty parts and damages.

(F) Earthing Strip Installation:

  • Marking the Route:

  • Mark the route of Earthing Strip with marking threads.
  • The route of Earthing Strip to be coordinated with other services and shall be confirmed.
  • Minimum space from the building structure and other services to be maintained (200 mm from the nearest point) to facilitate easy handling and maintenance.
  • Satiating of Earthing Strip / Electrode:

  • Hot-dip galvanized strip steel is aligned on simple straightening machines or on a parallel by hammer.

AA

  • Installation on Wall / Ground:

  • GI strips used for earthing shall be minimum 6 mm thick and hot dip galvanized.
  • If round GI conductors are used it shall have double the calculated area of cross-section.
  • For installing earth leads on walls, special clamps are employed. They firmly accommodate the earth leads and are easily mounted. They are directly inserted in the wall or screwed to the wall. Fixing should be spaced not more than 1 m apart.
  • Joints and junctions of earth leads and earthing concentration leads are to warrant a durable, safe and electrically well conductive connection.

AA - Copy

  • Where a Copper conductor is to be joined to GI, the joints should be tinned to prevent electrolytic action.
  • If atmosphere is corrosive, GI conductors shall not be used for earthing.
  • Earthing strips may be placed together with underground cables in cable Trench, but the heat from the cable must not be able to dry out the soil.
  • Earth conductors in trenches having power or multi-core cables should be fixed to the walls near the top (for example, 100 mm from the top).
  • Copper earth strip supported from or in contact with galvanized steel should be tinned to prevent electrolytic action.
  • Sharp bends required in aluminum strip should be formed by the use of a bending machine.
  • Earthing Strip which install below ground should be covered adequate insulating Sleeve for avoid corrosion.
  • Earthing Electrode (Plate / Pipe):

  • Minimum distance between earthing electrode (Plate /Pipe) and adjacent civil structure shall be 1.5 meter.
  • Earthing grid should be run at a minimum depth of 50 cm below the ground.
  • Since earthing electrodes will be damaged by corrosion, they are not to be placed in aggressive soil, in the vicinity of rubbish or in running waters.
  • Transformer and generator neutral shall be double earthed. One independent earth electrode shall be provided for neutral earthing
  • Earth electrodes (Plate /Pipe) shall be embedded as far apart as possible from each other. Mutual separation between them shall usually be not less twice the length of the electrode and are to be arranged in such a way as to prevent them from affecting each other.
  • Earthing Bus-Bar:

  • As far as possible, all earth connections shall be visible for inspection.
  • All connections shall be carefully made, if they are poorly made or inadequate for the purpose for which they are intended, loss of life or serious personal injury may result.
  • No cut-out, link or switch other than a linked switch arranged to operate simultaneously on the earthed or earthed neutral conductor and the live conductors,
  • All earth electrodes shall be interconnected using the conductors of largest size in the earthing system.
  • All non-current carrying metal parts of equipment’s shall be double earthed using conductors of adequate size.
  • Earthing bus bars for screwing on wall / other constructions, distance of bores 35 mm.For connecting Flat strip with bore by flat head screws M10 (with anti-rotation feature), nuts and spring washer.

AA - Copy (2)

  • Connection of Earthing Strip / Wire in Earthing Bus-Bar or to the body of equipment etc, such that it should be easily disconnected for testing purpose.
  • By welding and drilling the zinc layer on the steel is damaged leading to stronger corrosion at the defective points.
  • Welded joints are to be thoroughly cleaned from scale by means of a welder’s hammer prior to applying the anti-corrosive tape.
  • Earthing Strip / Wire Jointing:

  • Bolted, welded and pressed joints are permitted, In this case welded joints are being preferred Joints must be protected from corrosion.
  • All Earthing Strip joined together with two bolt arrangement, cutting, bending, shaping jointing with nut bolts & lap welding joints at all junctions. All connection made by electric arc welding with low hydrogen content electrodes.
  • Joints shall be allowed to cool down gradually to atmospheric temperature before putting any load on it. All oxide films that may have formed during welding must be removed from the welded joints
  • Joints should be provided with coating alternative layers of red oxide and aluminium. Joints are to be covered with hot bitumen
  • The interfaces of all ‘mechanical’ joins. Should be protected with a suitable electrical joint compound, particularly any bimetallic joints. All bimetallic joints should then be encapsulated in a grease impregnated tape, mastic compound or bitumastic paint, etc., to exclude moisture, In general, aluminum should only be used above ground and the connections to earth electrodes made above ground with bimetallic joints.  

AA - Copy (3)

  • Joints using GI conductors should be welded as far as possible and kept separated from air by a thick coating of tar or similar non-hygroscopic materials. In case bolted joints cannot be avoided than there should be a minimum of 2 bolts for sizes up to 25 mm x 6 mm, 3 bolts for sizes up to 31 mm x 6 mm and zig-zag bolting for large sizes.
  • When making a bolted type joint the surface of the Aluminum strip should be cleaned thoroughly by wire brushing and greased or an approved jointing compound applied immediately to both mating surfaces. Bolts should then be tightened and all excess grease or compound wiped off and discarded.
  • All crossings of conductors in the main earth grid should be jointed. Compression type joints may be used for stranded conductors.
  • Non-conductor strip should be drilled for a bolt having a diameter greater than one-third of the width of the strip. If this diameter will be exceeded, than a wider flag should be jointed to the strip.
  • In case of bolted joints, at least a bolt M 10 has to be taken. For joining the earth lead to the auxiliary earthing electrode in case of applying the protective measure “voltage-operated earth-leakage protection” a bolt M 6 will suffice (Always hardened and tempered bolts with hexagonal head are to be used).
  • Connections to natural earthing electrodes are preferably to be made outside the soil. At points where this is impossible and at joining faces being not metallic-bright, toothed lock-washers are to be used. At joining faces being metallic-bright, joints between earthing electrodes may be made by applying spring lock washer resp. plain lock washers. At the joints of earthing electrodes protection against corrosion is of utmost importance. It must be durable and fully effective.

AA - Copy (3) - Copy

 

OVERLAPPING OF EARTHING STRIP

SR.NO SIZE OF EARTHING STRIP MIN.OVERLAPING
1 20×3 20MM
2 20×6 20MM
3 25×3 25MM
4 25×6 25MM
5 32×6 25MM
6 40×5 50MM
7 40×6 50MM
8 50×6 50MM
9 50×10 50MM
10 75×6 50MM
11 75×10 50MM
NO’S AND SIZE OF NUT BOLT FOR JOINTING EARTHING STRIP
SR.NO SIZE OF EARTHING STRIP MIN.NUT BOLT REQUIRED MIN.SIZE OF NUT BOLT
1 20×3 2 NO’S 8X25MM
2 20×6 2 NO’S 8X25MM
3 25×3 2 NO’S 8X25MM
4 25×6 2 NO’S 8X25MM
5 32×6 2 NO’S 8X25MM
6 40×5 4 NO’S 8X25MM
7 40×6 4 NO’S 8X25MM
8 50×6 4 NO’S 10X25MM
9 50×10 4 NO’S 10X25MM
10 75×6 4 NO’S 10X25MM
11 75×10 4 NO’S

10X25MM

  • Jointing conductors:

  • Aluminum to aluminum: When possible, 4 joints on strip conductor should be Bolted or arc welded using either the tungsten inert-gas arc ( TIC ) or metal inert gas arc ( MIG ) techniques. Oxy-acetylene gas welding or brazing may also be used.
  • Rectangular Strip can be joined or terminated by drilling and bolting.
  • When making a bolted type joint, the surface of the aluminum should be cleaned thoroughly by wire brushing and greased or an approved jointing compound applied immediately to both mating surfaces. Bolts should then be tightened and all excess grease or compound wiped off and discarded. To ensure adequate contact pressure and avoid overstressing, torque spanners should be used. The conductor manufacturer’s literature should be consulted for further details for the joints and procedures.
  • Aluminum to copper:

  • Joints between aluminum and copper should be of the bolted type and be installed in the vertical plane at a minimum distance of 150 mm above ground level.
  • The rating surface of the aluminum should he cleaned thoroughly by wire brushing and greased or an approved jointing compound applied and the copper tinned. Grease or an approved jointing compound should be applied to the melting surface of the aluminum.
  • After bolt tightening by torque spanner, excess grease or compound should be wiped off and discarded, and the joint protected from the increase of moisture by the application of suitable plastics compound or irradiated polyethylene sleeve with mastic lining. Alternatively, the joint may be protected by a bitumastic paint.
  • Aluminum conductor connections to equipment should, where possible, be in the vertical plane. Surface preparation of the aluminum and the making of the joint should be as previously described. The finished joint should be protected by a bitumastic paint.
  • Earthing strip shall not have any cut-outs or switches or links.
  • All material, fitting etc. used for earthing and earthing pit should be of IS specified make and standards.
  • Two separate and distinct connections shall be taken out from plate earthing.
  • Interconnection of earth and main branch of earth should be made in such a way that reliable and good electrical contact is established.
  • The path of earthing strip should be minimum as possible, be out of reach of any person. For earth resistance please refer to IS-3043:1966-10 page –32. h).
  • Anti-corrosive measures: Earth strip should be protected against mechanical damages and corrosion. Fittings should be resistant to the corrosive agencies or be otherwise suitably protected. Joints and bonds may be protected with bitumen or embedded in plastic compound according to the local conditions.
  • No conductor strip should be drilled for a bolt having a diameter greater than one-third of the width of the strip. If this diameter would be exceeded then a flat should be jointed to the strip
  • Aluminum or copper conductors should not be drilled for fixing to structures. Clips should be used that prevent contact between conductor and structure and which are of suitable material so that there is no electrolytic action between clip and conductor.
  • Fixings should be spaced not more than 1 m apart. Earth conductors in trenches containing power and/or multi-core cables should be fixed to the walls near the top (e.g. 100 mm from the top).
  • Copper earth strip supported from or in contact with galvanized steel should be tinned to prevent electrolytic action. If sharp bends are required in aluminum strip they should be formed by the use of a bending machine to avoid stress concentration. Aluminum is prone to corrosion when in contact with Portland cement and mortar mixes. Contact of aluminum conductors with such materials should, therefore, be avoided by the use of stand-off fixings.

(G) Standards:

  • IS:3043-1987 :Code of Practice for Earthing (first revision)
  • Indian Electricity Rules :1956 (latest edition)
  • National Electrical Code :1985 of Bureau of Indian Standards
  • IEEE Guide for safety in a. c. substation grounding. No. ANSI/IEEE Standard 80-1986.

Calculate Size of Anchor Fastener for Water Pipe Support


  • Calculate Weight of Empty Water Pipe
  • Calculate Weight of Pipe including Liquid
  • Calculate weight  of Pipe Support
  • Calculate Tensile Load of Pipe and Support
  • Calculate Total Tensile Load
  • Calculate Size of Anchor Fastener

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Quick Reference -HVAC


HVAC Power Consumption (IS 1391)

Cooling Capacity (Kcal/Hr) Maximum Power Consumption (KW)
3000 1.65
4S00 2.3
6000 3.1
7500 3.6
9000 4.4
1 kcal/Hr= 1.16278 watt

 

HVAC Noise Level (IS 1391)

Rated Cooling Capacity (Kcal/Hr) Maximum Noise Level (DBA)
Indoor Outdoor
4500 or less 58 68
5000 or more 62 70

 

Centrifugal Fans (As per CPWD)

Type Characteristics Typical Applications Efficiency (%)
Radial High pressure, medium flow, efficiency close to tube-axial fans, power increases continuously Various industrial applications, suitable for dust laden, moist air/ gases 72–79
Forward curved blades Medium pressure, high flow, dip in pressure curve, efficiency higher than radial fans, power rises continuously Low pressure HVAC, packaged units, suitable for clean and dust laden air/ gases 60–65
Backward curved blades High pressure, high flow, High efficiency, power reduces as flow  increases beyond point of highest efficiency HVAC, various industrial applications forced draft fans, 79–83
Airfoil type Same as backward curved type, highest efficiency Same as backward curved, but for clean air applications 79–83

 

Axial Flow Fans (As per CPWD)

Type Characteristics Typical Applications  Efficiency (%)
Propeller Low pressure, high flow, low efficiency, peak efficiency close to point of free air delivery (zero static pressure) Air-circulation, ventilation, exhausts. 45–50
Tube axial Medium pressure, high flow, higher efficiency than propeller type, dip in pressure-flow curve before peak pressure HVAC, drying ovens, exhaust Systems 67–72
Vane axial High pressure, medium flow, dip in pressure-flow curve, use of guide vanes improves Efficiency exhausts High pressure applications including HVAC systems 78–85

 

Thickness of sheets for Rectangular Ductwork   (As per CPWD)

Longest side (mm) Minimum sheet thickness
For GSS  For Aluminum
750 mm and below 0.63 mm 0.8 mm
751 mm to 1500 mm 0.8 mm 1 mm
1501 mm to 2250 mm 1 mm 1.5 mm
2251 mm & above 1.25 mm 1.8 mm
All ducts shall be fabricated either from Galvanized Sheet Steel (GSS) conforming to IS: 277 or aluminum sheets conforming to IS:737. The steel sheets shall be hot dip galvanized with MAT finish with coating of minimum 120 grams per square meter (GSM) of Zinc, GI sheets shall be lead free, eco friendly and Ro HS compliant

 

Thickness of sheet for Round Ducts (As per CPWD)

Diameter of duct, mm Thickness of Sheet
For GSS  For Aluminum
150 to 500 mm 0.63 mm 0.8 mm
501 to 750 mm 0.8 mm 0.8 mm
751 to 1000 mm 0.8 mm 1 mm
1001 to 1250 mm 1 mm 1.5 mm
1251 mm and above 1.25 mm 1.8 mm
All sheet metal connections, partitions and plenums required for flow of air through the filters, fans etc. shall be at least 1.25 mm thick galvanized steel sheets, in case of G.I. sheet ducting or 1.8 mm thick aluminum sheet, in case of aluminum sheet ducting and shall be stiffened with 25 mm x 25 mm x 3 mm angle iron braces.
Circular ducts, where provided shall be of thickness as specified in IS: 655 as amended up to date.
Aluminum ducting shall normally be used for clean room applications, hospitals works and wherever high cleanliness standards are functional requirements

 

Duct’s Associated Items

Application Duct Width Angle size
Flanges Up to 1000 mm 35 mm x 35 mm x 3 mm
Flanges 1001 mm to 2250 mm 40 mm x 40 mm x 3 mm
Flanges More than 2250 mm 50 mm x 50 mm x 3 mm
Bracings Up to 1000 mm 25 mm x 25 mm x 3 mm
Bracings More than 1000 mm 40 mm x 40 mm x 3 mm
Support angles Up to 1000 mm 40 mm x 40 mm x 3 mm
Support angles 1001 mm to 2250 mm 40 mm x 40 mm x 3 mm
Support angles More than 2250 mm Size and type of RS section shall be decided in individual cases
Hanger rods shall be of mild steel and of at least 10 mm dia for ducts up to 2250 mm size, and 12 mm dia for larger sizes
 All nuts, bolts and washers shall be zinc plated steel. All rivets shall be galvanized or shall be made of magnesium – aluminum alloy. Self tapping screws shall not be used.

 

Comparison of the VRF/ VRV systems with the Central Chilled water system (As per CPWD)

Points VRF AC Chilled Water
based AC
Remarks
System Base It is Gas Base System It is Water Base System
Peak Power Demand 1.6KW/TR peak.
(Efficiency drastically reduces at high ambient)
1.3KW/TR Peak.
(IKW/TR<0.6 now for chilling units.)
Higher size & cost of Power Supply Capital Equipment like Transformers etc. & thus higher Cu losses in VRF system.
Annual Power
Consumption
1.15 to 1.20 1 Annually extra expenditure of 15 to 20% in electricity bills in VRF system.
Security & Safety of
Equipment &
System
Copper piping on
terrace & in building
MS piping VRF system equipments/ materials prone to theft & damage by miscreants
Terrace Space Almost 80% terrace is used for ODUs & Cu pipe & power cables Only Cooling Towers need to be installed at terrace. Problem of cleaning terrace & loss of water proofing also occurs over time.
Water Scarcity No water required Regular Supply of Water required for condenser cooling Major advantage in VRF system but, now STPs are generating water for meeting up to 75% of AC Plant demand. Water drift losses also being reduced by use of Geothermal Energy.
Air Quality of
Conditioned space
RH ,Co2, Bacteria, dust & other pollutants Control only to very
limited extent.
Full control Sick building syndrome is taken care of in Water based system with AHUs and demand based fresh air supply.
Service / Attending
to faults
Personnel have to go into the room. Problems of condensate dripping in rooms. Such problems
limited only in AHUs.
Long Term
Benefits
Maintenance Expensive  Low Cost Maintenance
Fire Safety Refrigerant in system goes to all areas in building and is combustible at high temperatures, releasing toxic products of combustion. Only water in AHUs and Air only in rooms through ducts. Refrigerant is limited to only within the Chilling Units. Water based system is safer.
Life 10 Years 15-20 Years
Applications Home or Small office with variable occupancy. More cost effective in room redundancy cases. Large office, continuously large air conditioning loads, proper controlled conditioning of  space.

 

Comparison of  VRF and VRV System (As per CPWD)

Application Variable Refrigerant Flow (VRF) system VRV System with Chiller based Air conditioners
Power Consumptions Up to 1.6 KW/TR of refrigeration. Up to 1.3 KW/TR of refrigeration.
Application Most of the VRF units are designed at an ambient temperature of 36°C, and so its use would not be suitable if the system is used in places with hotter temperature. Customization in design of the Chiller
system can be done with respect
to ambient temperature
 Performance in Hot Temperature If the system is used at hotter place
then system de-rates.
This is not the case in chiller based
system.
Space It requires more space for its
outdoor unit as maximum size of outdoor unit available is 60 hp, so a large no. of outdoor units would be required to fulfill the requirement of 3500-4000 TR
It can be managed by a single plant room.
Design its design is very complex Its design is comparatively less complex
COP its CoP (Coefficient of Performance)
varies from 3 to 4.2; a higher CoP
implies greater efficiency
Its CoP varies from 5.4 (for 750 TR chiller) to 6.3 (for 1000 TR chiller)
Efficiency Its part load efficiency is good if
used at more than 50 % rated
capacity
Its part load efficiency is good even at
one – third of the rated capacity.

 

Thumb Rules-VENTILATION & CEILING FAN


 

Recommended values for air changes  (NBC-5.2.2.1) & CPWD

Application Air Change per Hour
Assembly rooms 4 to 8
Bakeries 20 to 30
Banks/building societies 4 to 8
Bathrooms 6 to 10
Bedrooms 2 to 4
Billiard rooms 6 to 8
Cafes and coffee bars 10 to 12
Canteens 8 to 12
Cellars 3 to 10
Changing rooms 6 to 10
Churches 1 to 3
Cinemas and theatres 10 to 15
Club rooms 12, Min 12 to 15
Compressor rooms 10 to 12
Conference rooms 8 to 12
Corridors 5 to 10
Dairies 8 to 12
Dance halls 12
Dye works 20 to 30
Electroplating shops 10 to 12
Entrance halls 3 to 5
Factories and work shops 8 to 10
Foundries 15 to 30
Garages 6 to 8
Glass houses 25 to 60
Gymnasium 6
Hair dressing saloon 10 to 15
Hospitals sterilizing 15 to 20
Hospital wards 6 to 8
Hospital domestic 15 to 20
Laboratories 6 to 15
Launderettes 10 to 15
Laundries 10 to 30
Lavatories 6 to 15
Lecture theatres 5 to 8
Libraries 3 to 5
Lift cars 20
Living rooms 3 to 6
Mushroom houses 6 to 10
Offices 6 to 10
Paint shops (not cellulose) 10 to 20
Photo and X-ray dark room 10 to 15
Public house bars 12
Recording control rooms 15 to 25
Recording studios 10 to 12
Restaurants 8 to 12
Schoolrooms 5 to 7
Shops and supermarkets 8 to 15
Shower baths 15 to 20
Stores and warehouses 3 to 6
STP rooms 30
Squash courts 4
Swimming baths 10 to 15
Toilets 6 to 10
Underground vehicle parking 6
Utility rooms 15 to 30
Welding shops 15 to 30
Note: The ventilation rates may be increased by 50 % where heavy smoking occurs or if the room is below the ground.

 

Recommended values for air changes

Application Air Change per Minute
Assembly Hall 7
Auditorium 10
Barber Shop 6
Basement 8
Battery Room 4
Boiler Room 1
Bowling Alley 5
Engine Room 6
Gymnasium 8
Projection Booth 2
Church 15
Factory 6
Laundry 2
 Summer Cooling 1
Classroom 6
Forge Room 3
 Locker Room 3
 Toilet 3
Dance Hall 5
Foundry 4
Machine Shop 8
Transformer Room 1
 Department Store 6
Garage 5
Plating Room 3
Warehouse 12
 Dry Cleaning 5
General Office 10
Pressing Room 1
Welding Shop 2

 

TYPE A CEILING FANS (IS-374)

FAN SIZE AIR DELIVERY (m3/min) MAXIMUM INPUT (W)
900 140 42
1050 165 48
1200 215 50
1400 270 60
1500 300 63

 

Size of Ceiling Fan

Area Suggested Fan Size
Up to 9 Square Meters 900mm (36″)
Up to 12 Square Meters 1067mm (42″)
Up to 18 Square Meters 1200mm (48″)
Up to 30 Square Meters 1300mm (52″)
Up to 40 Square Meters 1400mm (56″)

 

Size and Number of Ceiling Fans for Rooms (As per NBC Table-10)

Room Width Room Length
Fan Size (mm) /No of Fan
4 Meter 5 Meter 6 Meter 7 Meter 8 Meter 9 Meter 10 Meter 11 Meter 12 Meter 14 Meter 16 Meter
3 Meter 1200/1 1400/1  1500/1  1050/2  1200/2  1400/2  1400/2  1400/2  1200/3 1400/3  1400/3
4 Meter 1200/1 1400/1 1200/2 1200/2 1200/2 1400/2 1400/2 1500/2 1200/3  1400/3  1500/3
5 Meter 1400/1 1400/1 1400/2  1400/2 1400/2  1400/2  1400/2  1500/2  1400/3  1400/3  1500/3
6 Meter 1200/2 1400/2  900/4  1050/4  1200/4  1400/4  1400/4  1500/4 1200/6 1400/6  1500/6
7 Meter 1200/2  1400/2  1050/4  1050/4  1200/4  1400/4  1400/4  1500/4  1200/6  1400/6  1500/6
8 Meter 1200/2  1400/2  1200/4  1200/4 1200/4  1400/4  1400/4  1500/4  1200/6 1400/6  1500/6
9 Meter 1400/2  1400/2  1400/4  1400/4  1400/4 1400/4  1400/4  1500/4  1400/6  1400/6  1500/6
10 Meter 1400/2  1400/2  1400/4  1400/4  1400/4  1400/4  1400/4 1500/4  1400/6  1400/6  1500/6
11 Meter 1500/2  1500/2  1500/4  1500/4  1500/4  1500/4  1500/4  1500/4  1500/6  1500/6 1500/6
12 Meter 1200/3  1400/3  1200/6 1200/6  1200/6  1400/6  1400/6  1500/6  1200/7  1400/9  1400/9
13 Meter 1400/3 1400/3  1200/6  1200/6 1200/6  1400/6 1400/6  1500/6  1400/9 1400/9 1500/9
14 Meter 1400/3  1400/3 1400/6  1400/6  1400/6 1400/6  1400/6  1500/6  1400/9 1400/9 1500/9

 

Ceiling Fan Criteria (As per NBC)

Capacity of a ceiling fan =55D m3/min ,D= the longer dimension of a room
Height of fan blades above the floor = (3H + W)/4, where H is the height of the room, W is the height of work plane.
Minimum distance between fan blades and the ceiling =0.3 m.

 

Size Your Fan for the Room (ENERGY STAR)

Room Size    Fan Size
Up to 75 sq. ft. 29 To 36 inches or smaller
75 to 144 sq. ft. 36 to 42 inches
144 to 225 sq. ft. 44 to 50 inches
225 to 400 sq. ft. 50 to 54 inches
Over 400 Sq. ft 54 To 72 inches multiple fans installed

 

Minimum Efficacy Levels of Ceiling Fans (ENERGY STAR )

Airflow (CFM) Minimum Efficacy Level (CFM/W)
Low At low speed, airflow of 1250 CFM and an efficiency of 155 cfm/W.
Medium At medium speed, airflow of 3000 CFM and an efficiency of 100 cfm/W.
High At high speed, airflow of 5000 CFM and an efficiency of 75 cfm/W.

 

Ceiling Fan Rod Extend Length

Ceiling Height Pole Length
8 Feet No Down rod
9 Feet 6 Inches
10 Feet 12 Inches
11 Feet 18 Inches
12 Feet 24 Inches
13 Feet 36 Inches
14 Feet 48 Inches
15 Feet 60 Inches
20 Feet or greater 72 Inches

 

Ceiling Fan Height Chart

Ceiling Height Distance
< 8 Feet Choose a low-profile ceiling fan. 18″ Minimum distance blade to wall. 7′ minimum distance blade to floor.
> 9 Feet Choose a ceiling fan down rod. 18″ Minimum distance blade to wall.

 

Distance between Two Fans

Fan Size Distance
36″ (900mm) 1.8 Meter
42″ (1000mm) 2 Meter
48″ (1200mm) 2.5 Meter
56″ (1400mm) 3 Meter

 

Fan Blade Pitch Angle and No of Blade

Fan Blade pitch It is the angle of fan’s blades (measured in degrees) and it is in conjunction with the fan motor,
It is show how well fan is able to circulate air.
Higher blade pitches typically move more air in cubic feet per minute, or CFM.
The optimal blade pitch for a ceiling fan is between 12 and 15 degrees.
Blade number It can contribute to the amount of air movement as well.
The typical ceiling fan comes standard with 4 or 5 blades.
Fans with more blades are usually quieter but also move less air.

 

Ceiling Fan Size Guide

Room Size Room Type Blade Span CFM Rating
Up to 100 Sq. Ft Bathroom, Breakfast Nooks, Utility Rooms, Small Bedrooms, Porches 29” To 36″           (700 to 900mm)
100 To 144 Sq. Ft Bathroom, Breakfast Nooks, Utility Rooms, Small Bedrooms, Porches 36” To 42″        (700 to 1000mm) 1,000 To 3,000
100 To 225 Sq. Ft Medium Bedrooms, Kitchens, Dining Rooms, Dens, Patios 44” To 50″         (1200 to 1270mm) 1,600 To 4,500
225 To 400 Sq. Ft Master Bedrooms, Family Rooms, TV Rooms, Small Garages, Gazebos Over 50” (1270mm) 2,300 To 6,500
Over 400 Sq. Ft Great Rooms, Large Garages, Basements, and Open Floor Plans Over 62” (1600mm) 5,500 To 13,500

 

Ceiling Fan Size

Room Size Fan Blade Sweep
< 90 Sq.Foot 15″ to 42″ (400 to 1000mm)
90 to 100 Sq.Foot 44″ to 46″ (1000 to 1200mm)
100 to 150 Sq.Foot 52″ to 54″ (1300 to 1400mm)
> 150 Sq.Foot 56″ to 70″ (1400 to 1800mm)

 

Ceiling Fan Speed and RPM

Speed Watt RPM Air Flow (M3/Hr) Efficiency (M3/Hr/Watt)
Low 62.3 171 8736 140
Medium 34.9 130 6774 197
High 15.2 86 4066 267

 

Various distance of Ceiling Fan in Room

Ceiling Fan Blades and Floor 7 ft
Ceiling Fan Blades and Ceiling 8 to 10 inches
Ceiling Fan Blades and Light fixtures. 39 inches
Ceiling Fan Blades and Wall 18 inches

 

Minimum Efficacy Levels of Ceiling Fans (ENERGY STAR )

Speed Air Flow Efficiency (CFM/Watt)
At low speed 1250 CFM 155 cfm/W
At medium speed 3000 CFM 100 cfm/W
At high speed 5000 CFM 75 cfm/W

 

Size of Rod / Cord for Hanging Light (As per NBC)

Nominal Cross-Sectional Area of Twin Cord mm for Hanging Light Maximum Permissible
Weight mm2  kg
0.5 2
0.75 3
1 5
1.5 5.3
2.5 8.8
4 14

 

Standard Exhaust Fan Size

Fan DIA (MM / inches) Speed (RPM) Input Power (W) Phase Current (A) M3/HR   (CFH) M3/MI   (CFM) Sound level dB
150/6″ 1200 24 Single 0.1 270 5 44 To 50
200/8″ 1350 28 Single 0.12 500 8 44 To 50
250/10″ 1350 36 Single 0.15 800 13 44 To 50
305/12″ 1400 50 Single 0.4 1710 29 50 To 55
305/12″ 900 50 Single 0.21 1145 19 35 To 40
380/15″ 1400 160 Single 0.75 3250 54 60 To 65
380/15″ 1400 150 Three 0.45 3250 54 60 To 65
380/15″ 900 90 Single 0.4 2000 33 50 To 55
380/15″ 900 100 Three 0.29 2000 33 50 To 55
457/18″ 1400 410 Single 1.7 6120 102 65 To 70
457/18″ 1400 410 Three 0.65 6120 102 65 To 70
457/18″ 900 150 Single 0.65 3900 65 55 To 60
457/18″ 900 150 Three 0.3 3900 65 55 To 60
610/24″ 700 240 Single 0.4 7100 118 55 To 60
610/24″ 900 500 Three 0.5 7100 118 55 To 60
610/24″ 900 500 Single 2.6 9400 157 60 To 65
610/24″ 900 500 Three 0.85 9400 157 60 To 65
750/30″ 900 870 Single 3.8 12000 200 70 To 75
750/30″ 900 910 Three 1.8 12000 200 70 To 75
900/36″ 700 1200 Three 2.4 28100 468 75 To 80

 

 

Electrical Thumb Rules-Illumination-(Part-20)


 

Watts & Light Brightness

Incandescent Watts  CFL Watts LED Watts Lumens (Brightness)
40 8 to 12 6 to 9 400 to 500
60 13 to 18 8 to 12.5 650 to 900
75 to 100 18 to 22 13 to 15 1100 to 1750
100 23 to 30 16 to 20 1800 to 2779
150 30 to 55 25 to 28 2780

 

Minimum Lumens

Incandescent (Watt) CFL , Halozan , LED (Minimum Lumen)
25 Watt 200
40 Watt 450
60 Watt 800
75 Watt 1100
100 Watt 1600
150 Watt 2700

 

Wattage Comparison Chart

Incandescent
/
Halogens
Mercury Vapor Metal    Halide High
Pressure
Sodium
Compact
Fluorescent
(CFLs)
Light
Emitting Diodes
(LEDs)
40 to 60 15 to 25 5 to 15 5 to 15 12 to 15 5 to 8
60 to 75 25 to 35 15 to 25 15 to 25 15 to 18 7 to 10
75 to 100 35 to 45 20 to 35 20 to 35 18 to 23 10 to 15
100 to 150 50 to 60 25 to 40 25 to 40 23 to 35 15 to 20
150 to 200 70 to 85 35 to 45 35 to 45 30 to 45 20 to 25
200 to 250 90 to 110 40 to 55 40 to 55 45 to 60 25 to 30

 

Luminous efficacy

Light type Typical luminous efficacy (lumens/watt)
Tungsten incandescent light bulb 12.5 to17.5 lm/W
Halogen lamp 16 to 24 lm/W
Fluorescent lamp 45 to 75 lm/W
LED lamp 30 to 90 lm/W
Metal halide lamp 75 to 100 lm/W
High pressure sodium vapor lamp 85 to 150 lm/W
Low pressure sodium vapor lamp 100 to 200 lm/W
Mercury vapor lamp 35 to 65 lm/W

 

Selection parameter of LED Bulbs

Parameter Average Good Best
Lumens/Watt 75 90 100
Power Factor 0.7 0.8 0.9
CRI 60 70 80
LED Life in Hours 15000 25000 50000

 

Available CRI of Various Lighting Sources

Source CRI
Incandescent / Halogens >95
T8 Linear Fluorescent 75 to 85
Cool White Linear Fluorescent 62
Compact  Fluorescent 82
Metal   Halide 65
High Pressure Sodium (HPS) 22
LED 80 to 98

 

Color Accuracy – CRI Chart

CRI Rating
>90 Great
80 to 90 Very Good
70 to 80 Good
60 to 70 Good
40 to 60 Poor

 

Color Temperature & CRI Chart

Kelvin Light Effect CCT CRI
< 3600K Incandescent Fluorescent (IF) 2750 89
< 3600K Deluxe warm white (WWX) 2900 82
< 3600K Warm white (WW) 3000 52
3200K to 4000K White (W) 3450 57
3200K to 4000K Natural white (N) 3600 86
Above 4000 K Light white (LW) 4150 48
Above 4000 K Cool white (CW) 4200 62
Above 4000 K Daylight (D) 6300 76
Above 4000 K Deluxe Daylight (DX) 6500 88
Above 4000 K Sky white 8000 88

 

Color Temperature & CRI

Lighting source Color Temperature Color Rendering Index
High Pressure Sodium Lamp 2100K 25
Incandescent Lamp 2700K 100
Tungsten Halogen Lamp 3200K 95
Tungsten Halogen Lamp 3200K 62
Clear Metal Halide Lamp 5500K 60
Natural Sun Light 5000K to 6000K 100
Day Light Bulb 6400K 80

 

Lighting Source CCT

Source Color temperature in Kelvin
Skylight (blue sky) 12,000 – 20,000
Average summer shade 8000
Light summer shade 7100
Typical summer light (sun + sky) 6500
Daylight fluorescent 6300
Xenon short-arc 6400
Overcast sky 6000
Clear mercury lamp 5900
Sunlight (noon, summer, mid-latitudes) 5400
Design white fluorescent 5200
Special fluorescents used for color evaluation 5000
Daylight photoflood 4800 – 5000
Sunlight (early morning and late afternoon) 4300
Bright White Deluxe Mercury lamp 4000
Sunlight (1 hour after dawn) 3500
Cool white fluorescent 3400
Photoflood 3400
Professional tungsten photographic lights 3200
100-watt tungsten halogen 3000
Deluxe Warm White fluorescent 2950
100-watt incandescent 2870
40-watt incandescent 2500
High-pressure sodium light 2100
Sunlight (sunrise or sunset) 2000
Candle flame 1850 – 1900
Match flame 1700
Skylight (blue sky) 12,000 – 20,000
Average summer shade 8000
Light summer shade 7100
Typical summer light (sun + sky) 6500
Daylight fluorescent 6300
Xenon short-arc 6400
Overcast sky 6000
Clear mercury lamp 5900
Sunlight (noon, summer, mid-latitudes) 5400
Design white fluorescent 5200
Special fluorescents used for color evaluation 5000
Daylight photoflood 4800 – 5000
Sunlight (early morning and late afternoon) 4300
Bright White Deluxe Mercury lamp 4000
Sunlight (1 hour after dawn) 3500
Cool white fluorescent 3400
Photoflood 3400
Professional tungsten photographic lights 3200
100-watt tungsten halogen 3000
Deluxe Warm White fluorescent 2950
100-watt incandescent 2870
40-watt incandescent 2500
High-pressure sodium light 2100
Sunlight (sunrise or sunset) 2000
Candle flame 1850 – 1900
Match flame 1700

 

CCT – Correlated Color Temperature

Kelvin Associated Effects Type of Bulbs Appropriate Applications
2700° Warm White, Very Warm White Incandescent bulbs Homes, Libraries, Restaurants
3000° Warm White mostly halogen lamps, Slightly  whiter  than ordinary incandescent lamps Homes, Hotel rooms and Lobbies, Restaurants, retail Stores
3500° White Fluorescent or CFL Executive offices, public reception areas, supermarkets
4100° Cool White Office, classrooms, mass merchandisers, showrooms
5000° Daylight Fluorescent or CFL Graphic industry, hospitals
6500° Cool Daylight Extremely  white‘ Jewelry stores, beauty salons, galleries, museums, printing

 

Average Life Cycle

Source Average Life
Incandescent / Halogens 1,000 to 4,000 hours
CFL 6,000 hours
LED 15,000 to 50,000 hrs

 

Lamp Properties

Option Life (hrs) Efficacy (lpw) CRI Color of light
LED 35,000-50,000 30-300 ≥70 White
High Pressure Sodium 20,000-24,000 50-110 ≤40 Orange
Metal Halide 6,000-15,000 72-76 75-90 White
Mercury Vapor 16,000-24,000 30-50 40-60 Blue-White
Fluorescent 10,000-24,000 40-140 20-80 White

 

Illuminance Levels for Signage Lighting

Light Intensity Foot candles Lux
Low 10 to 20 100 to 200
Medium 20 to 40 200 to 400
High 40 to 80 400 to 800

 

Types of Lamp Technologies

Type of Lamp Luminous

Efficacy

(lm/W)

Color

Rendering

Properties

Lamp life in

Hrs.

Lamp life in

Hrs.

High Pressure

Mercury Vapor (MV)

 

35-36 lm/W Fair 10000-15000

 

High energy use, poor lamp life
Metal Halide (MH) 70-130 lm/W Excellent 8000-12000 High luminous efficacy, poor lamp life
High Pressure

Sodium Vapor

(HPSV)

 

50-150 lm/W Fair 15000-24000 Energy-Efficient, poor color rendering

 

Low Pressure

Sodium Vapor

(LPSV)

 

100-190

lm/W

 

Very Poor 18000-24000 Energy-Efficient, very poor color rendering

 

Low Pressure

Mercury

Fluorescent Tubular

Lamp (T12 & T8)

 

30-90 lm/W Good 5000-10000 Poor lamp life, medium energy use, only available in low wattages

 

EE Fluorescent

Tubular Lamp (T5)

 

100-120

lm/W

 

Very Good 15000-20000 long lamp life, only available in low wattages

 

Light Emitting

Diode (LED)

 

70-160 lm/W Good 40000-90000 High energy savings, low O&M, long life, no

mercury, high

 

 

Comparison of Lamp Technology

Technology Mercury Vapor High Pressure Sodium Vapor Induction New Ceramic Induction New Ceramic LED
Description Older Very Common white light  HID light source Most common HID light source used in street lighting White light electrode less light source with long operating life White light HID technology White-light, solid-state light source
Pros Low initial cost Low initial cost maintenance-free White light Small size
Longer lamp life Longer lamp life High efficacy Longer lamp life Very long time life
White light High lamp efficacy (70-150) lumens/watt) Excellent color rendering index High lamp efficacy (115) lumens/watt) Switching has no effect on life
Sudden failure are uncommon Instant start and restrike operations High fixture efficiency Contains no mercury
No flickering, strobing or  noise low ambient  temperature operations
Low temperature operations High lumens efficacy
No flickering, strobing or  noise
Instant start and restrike operations
Cons Poor lamp efficacy (34-58) lumens/watt) Low CRI High initial cost High price High price
Low fixture efficiency Contains mercury Low lamp efficacy (36-64 ) lumens/watt) Lower luminaire efficacy Low luminous flux
Contains mercury Contains mercury Higher electricity consumption CRI can be low
Contains mercury Risk of glare

 

Restrick Rate of Bulbs

HID lamp type Time to reach 80% light output Time to Restrike
Mercury 5-7 min 3-6 min
Metal halide 2-4 min 10-15 min
High-pressure sodium 3-4 min 1 min

 

Mounting Height of Light according to Types of Bulbs

HID lamp type Watt Mounting Height
Mercury 100 Watt 8 Meter
175 Watt 10 Meter
250 Watt 15 Meter
400 Watt 23 Meter
1000 Watt 30 Meter
Metal halide 70 Watt 7 Meter
100 Watt 10 Meter
175 Watt 16 Meter
250 Watt 20 Meter
400 Watt 25 Meter
1000 Watt 35 Meter
High-pressure sodium 35 Watt 6 Meter
50 Watt 7 Meter
70 Watt 8 Meter
100 Watt 12 Meter
175 Watt 18 Meter
250 Watt 25 Meter
400 Watt 30 Meter
1000 Watt 38 Meter

 

Various Lamp Comparison

As per CPWD

Lamp type Range Luminous LUX Efficacy (lm/W) Average  Life (hr) Color Rendering (Ra)
CFL    18W-36W 1200-2900 60-80 15000 75-85
Fluorescent-T5 28W-54W 2900-4850  90-104 24000  80-90
Fluorescent-T8   18W-36W 750-3250 50-90 20000 80-85
Fluorescent-T12  20W-40W 950-2450  48-61 12000 50-75
Halogen  50W 1200 24 2000 75-90
Metal halide 70W-250W 5300-25000 76-100 12000 70-90
High pressure sodium vapor 70W-1000W 5600-130000 80-130 20000 20-65
Low pressure sodium vapor 55W-135W 8100-32000 100-230 20000 20-65
Induction lamp 70W-150W 6500-12000 80-95 100000 65-90
LED     3W-120W 750-14000 80-100 80000 65-90

 

Lamp Comparison As per CPWD

Lamp type LED (Warm White) LED (Cool  White) T5 Lamp CFL Lamp HPSV  Lamp Metal Lamp Halide
CRI 80-85 75 85 85 22 60-90
Efficiency in lm/w 80 132 90 70 95-110 65-70
Usable lm/w 55-65 >100 75-85 50-60 55-65 35-40
Life (Hrs.) 50k+ 50k+ 30k 8-10k 24k 10k-20K

 

Quick Reference-Fire Fighting (Part-2)


Size of the Mains for Fire Fighting as per Type of Building ( IS 3844 )

Mains of Fire Fighting Type of Building Building Height
100 mm single outlet landing valves I) Residential buildings (A)
a) Lodging housing 15 Meter to 45 Meter
b) Dormitory 15 Meter to 45 Meter
c) Family private dwellings 15 Meter to 45 Meter
d) Apartment houses 15 Meter to 45 Meter
e) With shopping area not exceeding 250 m2 15 Meter to 45 Meter
f) Hotel buildings up to 3 star grade 15 Meter to 24 Meter and area not exceeding 600 m2 per floor
100 mm single outlet landing valves II) Educational buildings (B)  Above 15 m but not exceeding 35 m
101 mm single outlet landing valves III) Institutional buildings (C)  Above 15 m but not exceeding 35 m
100 mm single outlet landing valves a) For hospitals and sanatorium with beds not exceeding 100no’s Above 15 m but not exceeding 25 m
100 mm single outlet landing valves b) For custodial places and mental institutions  Above 15 m but not exceeding 35 m
100 mm single outlet landing valves  IV) Assembly buildings (D) Above 15 m but not exceeding 24 m and total floor area not exceeding 500 m2/floor
100 mm single outlet landing valves V) Business buildings (E) Above I5 m but not exceeding 24m
100 mm single outlet landing valves VI) Mercantile buildings (F)  Above 15m but not exceeding 24 m
100 mm single outlet landing valves VII) Industrial buildings (G) Above 15 m but not exceeding 24 m
150mm with twin outlet landing VIII) All buildings classified  under(I) To (IV)  Above 45 m
150mm with twin outlet landing  IX) All buildings classified  under( v) above with shopping area not exceeding 250 m2  Above 24 m
150mm with twin outlet landing X) All buildings classified under (vi) above Above 24 m and area exceeding 600 m2
150mm with twin outlet landing XI) Hotel buildings of  4 star and 5 star grade Above 15 m
150mm with twin outlet landing XII) All buildings classified under II and III above Above 25 m/35 m as applicable
150mm with twin outlet landing XIII) All buildings classified under IV above Above 25 m and area exceeding 500m2/floor
150mm with twin outlet landing XIV) All buildings classified under V above Above 24 m
150mm with twin outlet landing XV) All buildings classified under VI above Above 24 m but not exceeding 35 m
150mm with twin outlet landing XVI) All buildings classified under VII above Above 24 m but not exceeding 35 m
150mm with twin outlet landing XVII) All storage buildings (H) Above 10 m but not exceeding 24 m

 

As per (IS 3844)

Type of Riser Internal hydrants form part of any of the following systems
a) Dry-riser system,
b) Wet-riser system,
c) Wet-riser-cum-down-comer system
d) Down-comer system.
Dry-Riser System ( for Cold Region ) Dry-riser main system can be installed in buildings under Group A (iI, ii, ii, iv ), where the height of building is above 15 m but not exceeding 24 m up to terrace level and where the water supply for firefighting is immediately available either through the underground water storage tank/tanks or through water mains/town’s main
Dry-riser system does not include hose reel, hose cabinets, fire hose and branch pipes.
Wet-Riser System Wet-riser system should be provided in the types of buildings according to the provision mentioned. The system should consist of a pipe or  number of pipes depending on the area and height of the buildings permanently charged with water under pressure with landing valves, hose reel, hose, branch pipe, etc, at every floor level
A provision of pressure differential switch to start the pump automatically, so that water under pressure is advisable for operational hydrant, hose reels, etc, as soon as the water is drawn from hydrant landing valves causing drop in pressure. The system also incorporates a stand-by pump to come into operation automatically when the normal power supply source fails.
The distribution of wet-riser installation in the building should be so situated as not to be farther than 30 m from any point in the area covered by the hydrant and at a height of 0.75 m to 1 m from the floor. The rising mains should not be more than 50 m apart in horizontal.
Fire service inlet with gate and non-return valve to charge the riser in the event of failure of the static pump directly from the mobile pump of the tie services should: be provided on the wet-riser system. The, fire service inlet for 100 mm internal diameter rising main should have collecting head with 2 numbers of 63 mm inlets and for 150 mm rising main, collecting head with 4 numbers of 63 mm inlets should be provided.
For wet-risers down-comer system, two pumps of different capacities one for the wet-riser and the other for down-comer system should be installed. The pumps should be fed from normal source of power supply and also by an alternative source in case of failure of normal source.
For a wet-riser system, two automatic pumps should be installed to independently feed the wet riser main, one of which should act as stand-by, each pump being supplied by a different source of power. The pump shall be arranged so that when acting as duty-pump, operate automatically when one or more hydrant is opened thus causing a drop in pressure. The stand-by pump should be arranged to operate automatically in case of failure of the duty pump. The system should have an interlocking arrangement so that only one of the pumps operate at a time.
Wet-Riser-cum-Down-Comer A wet-riser-cum-down-comer system should be provided in the type of buildings indicated in Table 1 of IS 3844 according to the provision mentioned.
Priming of the main pump and terrace pump in case of wet-riser-cum-down, or both the pumps in case of wet-riser installation, should be automatic. This can be achieved either by having flooded suction, or by a priming tank with foot valve arrangement. However, a flooded suction is preferable.
Down-Comer System Single headed landing valve, connected to a 100 mm diameter pipe taken from the terrace pump delivery should be provided at each floor/landing, A hose reel conforming to IS 884 : 1985 and directly tapped from the down-comer pipe should also be provided on each floor/landing.

 

As per ( IS 3844 )

Riser The position of risers should be located within lobby approach staircase or within, the staircase enclosure when there is no lobby. However, the risers or the landing valves connected
Landing Valve Landing valves should be installed on each floor level and on the roof, if accessible, in such
a way that control line of landing valve is 1 to 1.2 m above the floor level.
Fire Hoses In buildings with basements, the internal hydrants as well as the hose reel installations should be extended to cover the basement area also, over and above sprinkler system, as necessary. .
Fire hoses should be of sufficient length to, carry water from the nearest source of water supply to the most distant point in the area covered by a hydrant, by the normal route of travel. For each internal hydrant ( single headed ), there should be a total length of not less than.30 m of 63 mm conforming to Type A of IS 636 : 1988 or provided in two lengths of not more than 15 m each wire wound with coupling together with branch pipe conforming to IS 2871 : 1983
Such spare hoses also should be in length of not more than 15 m complete with coupling. Hoses and accessories should be kept in hose cabinet painted fire red and constructed preferably of wood with glass front
Hose Box Unless impracticable by structural considerations, the landing valves should always be housed in hose boxes. Such hose boxes should be made of MS plates of 2 mm minimum thickness with glass front. The size of the box should be adequate to accommodate single/double headed landing valves with 2 or 4 lengths of fire hose each of 15 m length, and one or two branch pipes. The hose reel may or may not be accommodated inside the hose box.
Building fitted with wet-riser/wet-riser-down-comer mains should, have access roads to within 6 m from the boundary line of the building and the nearest wet-riser stack should not be more than 15 m from the boundary line of the building.
Hose Reels In addition to wet-riser systems, first aid hose reels should be installed on all floors of buildings above 15 m in height. The hose reel should be directly taken from the wet-riser pipe by means of a 37 mm socket and pipe to which the hose reel is to be attached.
The hose reel should be sited at each floor level, staircase, lobby or mid-landing adjacent to, exits in corridors in such a way that the nozzle of the hose can be taken into every room and within 6 m of any part of a room keeping in view the layout and obstructions. Tbe doors provided for the hose reel recesses should he capable of opening to approximately 180”. when installation is in open areas, the position should be above head height and the nozzle retainer and tbe inlet valve should be at about 900 mm above floor level.
Air Valve To allow any trapped air in the rising main to escape when water is pressurized into system,air release valve should be incorporated above the highest outlet of each main.
External Hydrant For external hydrants, piping (water main ) should be laid preferably underground, to avoid it getting damaged by moving vehicles, etc. To avoid rusting, underground pipes should be either of cast iron conforming to IS 1536 in which case it should be properly treated with a coat of primary paint with two coats of bitumen paint. The pipes should be properly supported of pedestals – not more than 3 m apart. Underground pipes should be laid 1 m below to avoid damage during road repair, etc, and at road crossings where heavy vehicles are expected to pass, it should pass
Jockey Pump For bigger buildings or major installations, where chance of such leakage is very considerable, it is desirable to install a small pump ( using a small motor and 200/300 liter/min pump ) with pressure switches for automatic start and stop.
Using Wet-Riser System Pump for Partial Sprinkler System In main high rise buildings, the basement is used for car parking/housing transformers/or storages and other floors may be used as shopping areas departmental stores, etc, the total area used for such purpose being small, in such cases, the same wet-riser pump may be used for feeding the sprinkler system provided that:
a)the total area of the basement to be protected is less than 500 m2.
b) the total area utilized as shops departmental stores is less than 1000 m2.
c)the pump has a capacity of at least 2850 l/min with suitable motor.

 

AS per IS 15301

Foundation of Pump Pumps are to be mounted on a concrete foundation having minimum M grade of reinforced concrete as M15..
The thickness of the foundation shall be 50 mm minimum for small pumps up to 900 Liter/min capacity, 75 mm for pumps up to 2280 liter/min capacity and 100 liter/min for bigger pumps up to 4 500 liter/min. For extra ordinary big pumps, the thickness may go up to 150 mm. The size of the foundation shall cover the full length and width of the pump and at least 150 mm on the front and back of the pump and 75 mm on the sides as clearance.
Pump Room Location Normally, pump rooms shall be located 6 m away from all surrounding buildings and overhead structures
 Where this is not feasible, they may be attached to a building provided a perfect separation wall having 4 hour fire rating is constructed between the pump room and the attached building, the roof of the pump room is of RCC construction atleast 100 mm thick and access to the pump room is from the outside. The pump rooms shall normally have brick/concrete walls and noncombustible roof with adequate lighting, ventilation and drainage arrangements.
Transformer cubicles inside the sub-stations shall be separated from H.T. and L.T. cubicles and from each other by walls of brick/stone/concrete blocks or 355 mm thickness or of RCC of 200 mm thickness with door openings, if any, therein being protected by single fireproof doors having 2-hour fire resistance
Transformers installed outdoors, which are supplying power to fire pump shall also be located at least 6 m away from all surrounding buildings including sub-station or D.G. House, Where this is not feasible, all door and window openings of the building within 6 m of the transformers] shall be protected by single fireproof doors and 6 mm thick wired glasses in steel
framework respectively.

 

Requirement of the Fire Safety for Group A – Residential Buildings – Above 15 m in height  (IS 3844)

Type of Fire Protection Required A3- Dormitories, A4- Apartments Houses A5- Hotels
Fire Safety 15 Mts To 35 Mts 35 Mts To  45 Mts 45 Mts To 60 Mts Above 60 Mts 15 Mts To  30 Mts Above 30 Mts and A6 Hotels (Starred)
Fire Extinguishers Minimum 2 per floor Depending upon the Area and Travel Distance
Terrace Level Over Head Tank 25,000 liters capacity 5,000 liters (5,000 liters if basement) 10,000 liters capacity 25,000 liters capacity 20,000 liters capacity 20,000 liters capacity
Under Ground Water Tank Not Required 75,000 liters capacity 75,000 liters capacity 1,00,000 liters capacity 1,50,000 liters capacity 2,00,000 liters capacity
Terrace Fire Pump 900 LPM at Terrace level Tank Not Required Not Required Not Required Not Required Not Required
Fire Pump near Under Group Water Tank Not Required 1 electric pump & 1 Diesel pump of capacity 1620 LPM & Jockey Pump 180 LPM 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 1 electric pump & 1 Diesel pump of capacity 2280LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2850 LPM & Jockey Pump 180 LPM
Hose Reel Assembly Required Required Required Required Required Required
Down Comer System Required Not Required Not Required Not Required Not Required Not Required
Wet Riser System Not Required Required Required Required Required Required
Yard Hydrant Not Required Not Required Required Required Required Required
Fire Service Inlet Required Required Required Required Required Required
Manually Operated Fire Alarm Call Point (MCP) Required Required Required Required Required Required
Automatic Detection & Alarm System Not Required Not Required Not Required Required Required Required
Automatic Sprinkler System Required if area of basement exceeds 200 Sq.mts Required if area of basement exceeds 200 Sq.mts Required Required Required Required

 

Requirements of Fire Safety for Group B – Educational Buildings of above 15 mts in height (IS 3844)

Type of Fire Protection Required  B-1 Schools up to Senior Secondary Level 
B-2 All others/training Institutions  (Ground + One Storey)
Fire Extinguishers Minimum 2 per floor. Depending up on the Area and Travel Distance
Terrace Level Over Head Tank 25000 Liters Capacity
Under Ground Water Tank Not required
Terrace Fire Pump 900 LPM
Fire Pump near Under Ground Water Tank Not required
Hose Reel Assembly Required
Down Comes System Required
Wet Riser System Not required
Yard Hydrant Not required
Fire Service Inlet Required
Manually  Fire Alarm Call Point (MCP) Required
Automatic Detection and Alarm System Not required
Automatic Sprinkler System Required if area of basement exceeds 200 sq.mts

 

Requirement of the Fire Safety for Group C – Institutional Buildings – Above 15 m in height (IS 3844)

Type of Fire Protection Required C1- Hospitals,  Sanatoria and Nursing Home C2 – Custodial Institutions
C3 – Penal and Mental Institutions
Fire Safety (Active Measures) 15 Mts not exceeding 24 Mts not exceeding 15 Mts not exceeding 24 Mts not exceeding
24  Mts 30 Mts 24 Mts 30 Mts
Fire Extinguishers Minimum 2 per floor Depending upon the Area and Travel Distance
Terrace Level Over Head Tank 20,000 liters capacity 20,000 liters capacity 10,000 liters capacity 20,000 liters capacity
Under Ground Water Tank 1.00,000 liters capacity 1,50,000 liters capacity 75,000 liters capacity 1,00,000 liters capacity
Terrace Fire Pump Not required Not Required Not Required Not Required
Fire Pump near Under Group Water Tank 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM
Hose Reel Assembly Required Required  Required Required
Down Comer System Not Required Not Required Not Required Not Required
Wet Riser System Required Required Required Required
Yard Hydrant Required Required Required Required
Fire Service Inlet Required Required Required Required
Manually Operated Fire Alarm Call Point (MCP) Required Required Required Required
Automatic Detection & Alarm System Required Required Required Required
Automatic Sprinkler System Required Required Required Required

 

Requirement of the Fire Safety for Group D – Assembly Buildings Above 15 m in height (IS 3844)

Type of Fire Protection Required D1 – Theater over  1000 persons, D2 up to 1000 persons  D3 – Permanent Stage over 300 persons D6 – Not exceeding 30 mtrs D7 – Elevated or underground for assembly not  covered D1-D6
D4 – up to 300 persons, D5 all others
Fire Safety 15 Mts To 24 Mts 24 Mts To 30 Mts 15 Mts not exceeding 24 Mts not exceeding
Fire Extinguishers Minimum 2 per floor Depending upon the Area and Travel Distance
Terrace Level Over Head Tank 10,000 liters capacity 20,000 liters capacity 20,000 liters capacity 20,000 liters capacity
Under Ground Water Tank 75,000 liters capacity 1,00,000 liters capacity 1,00,000 liters capacity 1,00,000 liters capacity
D1-D5, 2,00,000 liters for D6 Multiplex
Terrace Fire Pump Not required Not Required Not Required Not Required
Fire Pump near Under Group Water Tank 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2850 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2850 LPM & Jockey Pump 180 LPM
Hose Reel Assembly Required Required Required Required
Down Comer System Not Required Not Required Not Required Not Required
Wet Riser System Required Required Required Required
Yard Hydrant Required Required Required Required
Fire Service Inlet Required Required Required Required
Manually Operated Fire Alarm Call Point (MCP) Required Required Required Required
Automatic Detection & Alarm System Required Required Required Required
Automatic Sprinkler System Required Required Required Required

 

Requirement of the Fire Safety for Group E – Business Buildings  Above 15 m in height (IS 3844)

Type of Fire Protection Required E1  offices, banks, professional establishments, like offices of architects, engineers, doctors, lawyers and police stations, E2 – Laboratories research establishments, libraries and test houses.  E3 – Computer installations, E4 – Telephone Exchanges,  E5
Fire Safety 15 Mts To 24 Mts 24 Mts To 30 Mts Above 30 mt
Fire Extinguishers Minimum 2 per floor Depending upon the Area and Travel Distance Minimum 2 per floor Depending upon the Area and Travel Distance Minimum 2 per floor Depending upon the Area and Travel Distance
Terrace Level Over Head Tank 10,000 liters capacity 20,000 liters capacity 20,000 liters capacity
Under Ground Water Tank 75,000 liters capacity 1,00,000 liters capacity 2,00,000 liters capacity
Terrace Fire Pump Not required Not Required Not Required
Fire Pump near Under Group Water Tank 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2850 LPM & Jockey Pump 180 LPM
Hose Reel Assembly Required Required  Required
Down Comer System Not Required Not Required Not Required
Wet Riser System Required Required Required
Yard Hydrant Required Required Required
Fire Service Inlet Required Required Required
Manually Operated Fire Alarm Call Point (MCP) Required Required Required
Automatic Detection & Alarm System Required Required Required
Automatic Sprinkler System Required Required Required

 

Requirement of the Fire Safety for Group F Mercantile Building  Above 15 m in height (IS 3844)

Type of Fire Protection Required F1  – Shops, Stores up to 500 Sq.m, F3 – Underground shopping centre and  Storage
F2 – Shops, Stores more than 500 Sq. mtrs.
Fire Safety (Active Measures) 15 Mts To 24 Mts 24 Mts To 30 Mts
Fire Extinguishers Minimum 2 per floor Depending upon the Area and Travel Distance
Terrace Level Over Head Tank 10,000 liters capacity 10,000 liters capacity 10,000 liters capacity
Under Ground Water Tank 1,00,000 liters capacity 1,50,000 liters capacity 1,50,000 liters capacity
Terrace Fire Pump Not required Not Required Not Required
Fire Pump near Under Group Water Tank 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 2 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM
Hose Reel Assembly Required Required Required
Down Comer System Not Required Not Required Not Required
Wet Riser System Required Required Required
Yard Hydrant Required Required Required
Fire Service Inlet Required Required Required
Manually Fire Call Point (MCP) Required Required Required
Automatic Detection & Alarm System Required Required Required
Automatic Sprinkler System Required Required Required

 

Requirement of the Fire Safety for Group G Industrial Buildings  Above 15 m in height not to be permitted 18 Mts in height (IS 3844)

Type of Fire Protection G1  – Low Hazard Industries G2 – Moderate Hazard Industries
BUILT UP AREA
Fire Safety Up to 100 Sq.mt More than  100 Sq.mt. & up to 500 Sq.mt More than 500 Sq.mtrs Up to 100Sq.mtrs More than  100Sq.mtrs and up to 500 Sq.mtrs More than  500Sq.mtrs and up to 1000 Sq.mtrs Up to 1000 Sq.mt
Fire Extinguishers Minimum 2 per floor Depending upon the Area and Travel Distance
Terrace Level Over Head Tank 5000 liters in case of basement area exceeds 200m2 5000 liters add 5000 liters if the provision of sprinkler in basement 10,000 liters capacity 10,000 Liters capacity 10,000 Liters capacity 20,000 Liters capacity 20,000 Liters capacity
Under Ground Water Tank Not required Not required 1,00,000 liters Not required Not required 75,000 Liters capacity 1,00,000 Liters capacity
Terrace Fire Pump 450 LPM 450 LPM 450 LPM 900 LPM 900 LPM 900 LPM 900 LPM
Fire Pump near Under Group Water Tank Not required Not required 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM Not required Not required 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM 1 electric pump & 1 Diesel pump of capacity 2280 LPM & Jockey Pump 180 LPM
Hose Reel Assembly Not required Required Required Required Required Required Required
Down Comer System Not required Required Required Not required Not required Required Required
Wet Riser System Not required Not required Required Not Required Not Required Required Required
Yard Hydrant Not required Not required Required Not Required Not Required Required Required
Fire Service Inlet Not required Not required Required Not Required Not Required Required Required
Manually Operated Fire Alarm Call Point (MCP) Not required Not required Not Required Not Required Not Required Required Required
Automatic Detection & Alarm System Not required Not required Required Not Required Not Required Required Required
Automatic Sprinkler System Required (if there is basement) Required (if there is basement) Required Required Required Required Required

Quick Reference-Fire Fighting (Part-1)


 

Class of Fire

CLASS Type of Fire Type of Fire Extinguisher
Class A Fires involving Paper, Wood, Textile, Packing materials and the like. Water, foam, ABC dry power and halocarbons.
Class B Fires involving Oil, Petrol, Solvent, Grease, Paints, Celluloid and the like. Foam, dry powder, clean agent and carbon dioxide extinguishers
Class C Fires involving Electrical Hazards, Motor Vehicle Gaseous substance under pressure. Dry powder, clean agent and carbon dioxide extinguishers
Class D Fires involving Chemicals, Metal and active like

Magnesium ,titanium

Extinguishers with special dry powder for metal tires

 

Area covered by Fire Extinguisher (NBC)

Type of Fire Extinguishers Coverage (Floor) Area
Water/ Sand Bucket 100 sq.mt.
Sprinklers 6 sq.mt.
Extinguishers (9 Liter) 600 sq.mt.
Heat Detectors 16 sq.mt.
Hydrant Riser (Outlet 100 mm dia with landing valve and First aid hose reel) 930 sq.mt
Smoke Detectors 50 sq.mt.

 

Water Requirement for the Fire Fighting (AS per NBC)

Q = 3000 P
Q = Fire demand in Liters/Minutes
P = Population in Thousands
Note:  The above rate must be maintained at a minimum pressure of 1 to 1.5 kg / cm2 for at least four hours.

 

Water Requirement for Wet Riser/Down Corner System (As per NBC -TABLE 4)

Residential Buildings U.G. Water Storage Tank Static Terrace Tank
15 m to 30 m 50,000 lts 10,000 lts
30 m to 45 m 1,00,000 lts 20,000 lts
Above 45 m 2,00,000 lts 40,000 lts

 

Water Requirement for Wet Riser/Down Corner System (As per NBC -TABLE 5)

Business Building U.G. Water Storage Tank Static Terrace Tank
15 m to 30 m 100000 lts (50000 lts if covered area in G.F is less than 300sq.m.) 20,000 lts
30 m to 45 m 20000 lts 20,000 lts
Above 45 m 250000 lts 50,000 lts

 

Classification of fire Pumps (As per IS 15301)

Pump Size Location of Pump Installation
450 Liter/Min Pumps to be installed on the terrace to feed the Down Comer System.
900 Liter/Min Pumps to be installed on the terrace to feed the Down Comer System.
2280 Liter/Min Pumps are to be housed in the pump house.
2850 Liter/Min Pumps are to be housed in the pump house.
4500 Liter/Min Pumps are to be housed in the pump house.
For special risks 6700 Liter/Min Pumps are to be housed in the pump house.

 

Suction and Delivery Pipe Sizes (IS 3844)

Pump Size Pump Location Suction Delivery
450 Liter/min Terrace 50 mm 50 mm
 900 Liter/min Terrace 75 mm 50 mm
1400 Liter/min Terrace 100 mm 100 mm
2280 Liter/min Fire Pump 150 mm 150 mm
2850 Liter/min Fire Pump 200 mm 150 mm
4500 Liter/min Fire Pump 250 mm 200 mm
6700 Liter/min Fire Pump 250 mm 200 mm

 

Different Types of Fire Extinguishers for Different Classes of Fires ( IS 2190 )

Type of Extinguisher IS Type of Fires
Class A Class B Class C Class D
water type (gas cartridge) IS 940 , IS 13385 S NS NS NS
water type (stored pressure) IS 6234 S NS NS NS
mechanical foam type (gas cartridge) IS 10204, IS 13386 S S NS NS
mechanical foam type (stored pressure)  IS 14951,IS 15397 S S NS NS
dry powder type (stored pressure)  IS 13849 S S S NS
dry powder type (gas cartridge)  IS 2171 , IS 10658 S S S NS
dry powder type for metal fires  IS 11833 NS NS NS S
carbon dioxide type  IS 2878, IS 8149 NS S S NS
clean agent gas type  IS 15683 S S S NS
halon 1211 type IS 4862 , IS 11108 S S S NS

 

PRESSURE TESTING OF FIRE EXTINGUISHERS  ( IS 2190 )

Type of Extinguisher IS Test Interval (Year) Test Pressure (kg/cm2) Pressure Maintained for Min. (kg/cm2)
Water type (gas cartridge) IS 940 3 35 2.5
Water type (stored pressure)  IS 6234 3 35 2.5
Water type (gas cartridge) IS 13385 3 35 2.5
Mechanical foam type (gas cartridge)  IS 10204 3 35 2.5
Mechanical foam type (stored pressure) IS 15397 3 35 2.5
Mechanical foam type (gas cartridge)  IS 13386 3 35 2.5
Mechanical foam type (gas cartridge) 135 liter  IS 14951 3 35 2.5
Dry powder ( stored pressure) IS l3849 3 35 2.5
 Carbon dioxide IS 2878 5 250 2.5
 Clean agent IS 15683 3 35 2.5
Dry powder (gas cartridge) IS2171, IS10658 3 35 2.5

 

LIFE OF FIRE EXTINGUISHERS ( IS 2190)

Type of Extinguisher Life Time, Year
Water type 10
Foam type 10
Powder type 10
Carbon dioxide 15
Clean agent 10

 

RECOMMENDATIONS FOR INSTALLATION OF FIRE EXTINGUISHERS  ( IS 2190 )

Occupancy Type of Occupancy Nature of Occupancy Class of
Fire
Typical Examples
Group A Residential buildings Low Hazard CLASS A Lodging or rooming, one or two family houses, private dwellings, dormitories, apartment houses, flats, up to 4 star hotels, etc
  Low Hazard CLASS C Small kitchens having LPG connection, electrical heaters, etc
  Medium Hazard CLASS A Multi-storied buildings, multi-risk buildings, five star hotels, etc
Group B Educational buildings Low Hazard CLASS A Tutorials, vocational training institutes, evening colleges, commercial institutes
  Medium Hazard CLASS A Schools, colleges, etc
Group C Institutional buildings Medium Hazard CLASS A Hospitals, sanatoria, homes for aged, orphanage jails, etc
Group D Assembly buildings-D-1 High Hazard CLASS A Theatres, assembly halls, exhibition halls, museums, restaurants places of worship, club rooms, dance halls, etc, having seating capacity of over 1 00 persons
Assembly buildings-D-2 High Hazard CLASS A Theatres, assembly halls, exhibitions halls, museums, restaurants, places of worship, club rooms, dance halls, etc, having seating capacity less than 1 000 persons
Assembly buildings-D-3 High Hazard CLASS A Theatres, assembly halls, exhibition halls, museums, restaurants, places of worship, club rooms, dance halls, etc, but having accommodation for more than 300 persons, but less than 1 000 persons, with no permanent seating arrangement
Assembly buildings-D-4 / D5 Low Hazard CLASS A Theatres, assembly halls, exhibition halls, museums, restaurants, places of worship, club rooms, dance halls, etc, but having accommodation less than 300 and those not covered under D-l to D-3
Group E Business buildings-E-1 Special Hazard CLASS A Offices, banks, record rooms, archives, libraries, data processing centers, etc
Business buildings-E-2 Medium Hazard CLASS B Laboratories, research establishment, test houses, etc
Business buildings-E-3 Special Hazard CLASS A Computer installations
Group F Mercantile buildings Medium Hazard CLASS A Shops, stores, markets, departmental stores,
underground shopping centers, etc
Group G Industrial buildings Low Hazard CLASS A Small industrial units
Medium Hazard CLASS A Corrugated carton manufacturing units, paper cane units, packing case manufacturing units, cotton waste manufacturing units
HH CLASS A Large number yards, saw mills, godowns and warehouses storing combustible materials, cold storages, freight depots, etc
Low Hazard CLASS B Demonstration chemical plants, small chemical processing plants, pilot plants, etc
Medium Hazard CLASS B Workshops, painting shops, large kitchens, industrial canteens, generator rooms, heat treatment shops, tread rubber manufacturing units, petrol bunks, tubes and Haps units, etc
High Hazard CLASS B Petroleum processing units, chemical plants, industrial alcohol plants, effluent treatment plants, etc
High Hazard CLASS C Fertilizer plants, petrochemical plants, LPG bottling plants, etc
High Hazard CLASS D All processes involving use of combustible highly flammable materials, reactive metals and alloys, including their storage
Group H Storage buildings Medium Hazard CLASS B Flammable liquid stores, storage in drums and cans in open, paints and varnishes go down
High Hazard CLASS B Tank farms, chemical and petroleum bulk storage depots, large service stations, truck and marine terminals, underground LDO/furnace oil storage yards, etc
Medium Hazard CLASS C LPG distribution godown/office, distribution storage godowns/offices of D, N, H, Argon and other industrial gases
High Hazard CLASS C Storage and handling of gas cylinders in bulk, gas plant, gas holders ( Horton), spheres, etc
Group J Hazardous Buildings used for storage, handling, manufacture and processing of highly combustible explosive materials. (Risks involved in terms of class of fire and intensity of fire has to be assessed on case to case basis and statutory authorities to be consulted, environmental factors and mutual aid facilities to be taken into account before deciding on the fire extinguisher requirements.)

 

RECOMMENDED  EQUIPMENT TO BE INSTALLED ( IS 2190 )

Class of Fire  Occupancy No of Fire Systems
CLASS A Low Hazard One 9 liter water expelling extinguisher or ABC 5 kg/6 kg fire extinguisher, for every 200 m2 of floor area or part thereof with minimum of two extinguishers per compartment or floor of the building.
Medium Hazard Two 9 liter water expelling extinguishers or ABC 5 kg / 6 kg fire extinguisher, for every 200 m2 with minimum of 4 extinguishers per compartment floor.
Medium Hazard Provision as per MH occupancy; in addition to one 50 liter water CO2/25 kg ABC fire extinguisher for every 100 m2 of floor area
Special Hazard One 4.5 kg capacity carbon dioxide or one 2/3 kg capacity clean agent extinguisher for every 100 m2 of floor area or part thereof with minimum of two extinguishers
CLASS B Low Hazard One 9 liter foam extinguisher, mechanical or BC or ABC, 5 kg/6 kg fire extinguisher, for every 200 m2 of floor area or part thereof with minimum of two extinguishers per compartment or floor.
Medium Hazard Two 9 liter foam extinguisher, mechanical type, or 5/6 kg dry powder extinguisher ( or one of each type) for every 200 m2 area with minimum of four extinguisher per compartment
Medium Hazard Provision as per MH, and in addition to one 50 liter mechanical foam type extinguisher or 25 kg BC fire extinguisher for every 100 m2 or part thereof one l35 liter foam mechanical extinguisher for every 300 m2 of floor area
CLASS C Low Hazard One 2/3 kg dry powder of clean agent extinguisher for every 20 m2 of floor area
Medium Hazard One 10 kg dry powder extinguisher (stored pressure) or 6.5 kg  carbon dioxide extinguisher or 5 kg clean agent for 100 m2 of floor area or part thereof, with minimum of one extinguishers of the same type for every compartment;
High Hazard Dry powder extinguisher (stored pressure) of 10 kg or 6.5 kg CO2 extinguisher, or 5 kg clean agent extinguisher for every 100 m2 of floor area or part thereof, subject to a minimum of two extinguishers of same type per room or compartment.
CLASS D High Hazard One 10 kg dry powder extinguisher with special dry powder for metal fires for every 100 m2 of floor area or part thereof with minimum of two extinguishers per compartment/room

 

Internal Electrical Work -Abstract of CPWD


 

Circuits:

Topic Abstracts
Lighting Circuit Per Circuit Not more than 10 Points of Lighting or Total 800Watt which is less
Power Circuit For Residential Per Circuit Less than 2 No of 5A/15A Plug Socket
Power Circuit For Non Residential Per Circuit Less than 1 No of 5A/15A Plug Socket
Plug Socket In Residential wiring ,wiring of Socket outlet shall be done by copper Cable only
Min Size of Wire For Lighting Circuit Smallest size of conductor shall be 1.5 Sq.mm
Min Size of Wire For Power Circuit Smallest size of conductor shall be 4 Sq.mm

Plug Socket

Plug Socket 5A/6A or 15A/16A Socket shall be installed at following heights:                                                                   =For Non Residential building 23cm above  floor

=For Kitchen 23cm above  Platform. 

=For Bathroom not Socket is provided in bathroom MCB/IC will be 2.1 mt from fixed appliance and at least 1 mt away from Shower

Switch Board /  D.B

Operating Rod Operating Rod/Handle of Distribution Board at the height of min 2mt
D.B Clearance Clear Distance in front of Switch Board/D.B shall be min 1 mt.
D.B Clearance If there may be bare connection at back of Switch Board than space behind S/W shall be either less than 20cm or more than 75cm
D.B Clearance No fuse Body shall be mounted within 2.5 com edge of D.B or Panel
D.B Clearance Clearance between 2.5 cm is maintained between opposite polarity
Switch Box Switch Box or Regular Box shall be mounted normally 1.25 mt from floor level.

Fan Hook

Fan Hook For Fan Hook in concrete roof 12mm dia MS Rod in ‘U’ Shape, horizontally Leg at Top at least 19 cm on either side.

Connection between adjustment Building (Out House, Garages)

Safety Clearance If the distance with adjustment building is less than 3 mt and there is no any Road interval than GI pipe of suitable size shall be installed. This pipe shall be exposed on wall at height of not less than 2.5 mt.
Safety Clearance If the distance with adjustment building is more than 3 mt and there is any Road interval than GI pipe of suitable size shall be installed. This pipe shall be exposed on wall at height of not less than 4 mt.

Conduit

Metallic Conduit Shall be used for Industrial wiring, Heavy mechanical Stress, shall be ISI marked, The Thickness shall not be less than 1.6mm(16SWG) for conduits up to 32mm Dia and not less than 2mm (14SWG) for conduit above 32mm Dia.
Metallic Conduit No steel conduit less than 20 mm Diameter shall be used.
Metallic Conduit For rigid Conduit IS:2509/IS:3419 and For Flexible Conduit IS:6946.
Metallic Accessories All Metallic conduit accessories shall be threaded type (Not pin grip, clamp grip)
Metallic Accessories Saddle for surface conduit work on wall shall not less than 0.55mm(24 gauge) for conduit up to 25mm Dia not less than 0.9mm (20 gauge) for larger Dia
Metallic Outlets Fore Cast Boxes:

Wall thickness shall be at least 3mm.                                                                                                

For Welded mild Steel Box:

Wall thickness shall not be less than 1.2mm (18 gauge) for Boxes up to size 20cmX30cm. Above This size 1.6mm(16guage)thick MS Boxes shall be used.

Metallic Outlets Clear depth of Out less Box shall not be less than 60mm.

This will be increased as per mounting of Fan regulator

Bends in Conduits Bending radius not less than 7.5 cm
Fixating Conduits on Surface Conduits shall be fixed by saddles not less than 1mt interval but in case of coupler/Bends in either side of saddles, The saddle shall be fitted 30 cm from fitting.
Non Metallic Accessories Normally grip Type.
Non Metallic Outlet(PVC Box) PVC Box IS:5133(PartII) thickness not less than 2mm,Clear depth of PVC Boxes not less than 60mm.
Non Metallic Surface Conduit Conduits shall be fixed by saddles not less than 60cm interval but in case of coupler/Bends in either side of saddles, The saddle shall be fitted 15 cm from fitting.

Junction Box

Junction Box Depth of Junction Box shall be min 65mm as per IS: 2667.

Fish Wire

Fish Wire GI fish wire of 1.6mm/1.2mm (16SWG) shall be used.

Bus bar

Bus bar Busbar shall be 100A,200A,300A,400A,500A,600A,800A
Bus bar The Cross-section area of Bus bar shall be same as Phase Bus bar (Up to 200A) for higher Capacity Neutral Bus bar must be not less than half cross section areas of Phase Bus bar.
Bus bar Bus bar shall be suitably installed with PVC sleeve/Tap.
Bus bar Bus bar Chamber shall be fabricated with MS angle for Frame work and sheet steel of thickness not less than 1.5mm.
Bus bar Minimum clearance between phase to earth shall be 26mm and phase to phase shall be 32mm.

Bus bar Trucking

Bus bar Trucking  Bus bar Trucking are generally used for interconnection between T/C over 500KVA/D.G set over 500KVA and their switch Board Panel.
Bus bar Trucking Bus bar Trucking enclosure sheet steel of min 2mm thickness

Earthing

Earthing Type of earthling are Pipe earthling/Plate earthling/Strip earthling.
Earthing Length of Buried strip shall not be less than 15mt.
Earthing Two copper strip, each size 50mmX5mm shall be provided as each bus bar in 11KV S/S or D.G generally.
Earthing Each strip should be connected separately to earth.
Earthing Two no of Body earthling of T/C,Panel,D.G are connected to earth Bus.
Earthing Neutral Leads of T/C,D.G shall not be connected to earth Bus.
Earthing The minimum Cross-section are of protective conductor (Not contained within cable or wire) 2mm Dia(14SWG) for Copper, 2.5mm Dia(12SWG) for G.I, 2.24mm Dia(13SWG) for Aluminum.
Earthing Earthing Pit shall not be closer than 1.5mt from Building.
Earthing Top of Pipe earthling electrode shall not be less than 20cm below the ground
Earthing Plate electrode shall be buried in ground with face vertical and it’s Top not less than 3mt below ground level.
Earthing The strip of earthling electrode shall be buried in trench not less than 0.5m deep.
Earthing If strip electrode cannot be laid in straight length. It may be Zigzag with deviation up to 45 Degree from axis of strip.
Earthing In Plate Earthing Dia of water pipe shall not be less than 20mm and in Pipe earthling reducer of 40mmX20mm shall be used.
Earthing Earthing Pit Size shall be not less than 30cmX30cmX30cm.
Earthing Thickness of MS cover of earthling pit shall be not less than 6mm and having locking arrangements.
Earthing Earthing resistance of each electrode shall be less than 5Ω and for Rocky Soil not less than 8Ω
Earthing Earthing conduit for earthling wire shall be Medium class 15mm Dia GI pipe and for Earthing Strip shall be medium class 40mm Dia GI Pipe.

Conductor Clearance(min)

Cable crossing The horizontal and vertical distance between Power and Communication cable shall not be less than 60cm.
Railway crossing After taking approval of railway authority, Cable under railway track shall be min 1mt from bottom of sleeper under RCC or cast Iron Pipe.
Railway crossing Cable in parallel to Railway track shall be min 3mt far away from centre of nearest Track.
Cable Laying in Pipe For Single Conductor Shall be min 10cm Dia and more than Two Cable shall be min 15cm Dia.
Cable in Road Crossing In Road Crossing Cable shall be laid min 1 mt below Road in Pipe.

Cable trench

Cable trench For single cable: For below 11Kv.Min length of Trench shall be 35cm and depth shall be min 75cm ( with sand cushioning of 8cm at bottom +Cable+ protective covering/Sand cushioning of 17cm above Cable) and without Cushioning Depth shall be 75cm+25cm.
Cable trench For single cable: For above 11Kv.Min length of Trench shall be 35cm and depth shall be min 1.2mt ( with sand cushioning and protective covering).
Cable trench For multi cable in horizontal level: Min distance between two cable shall be 20cm and min distance between cable and edge of trench on both side shall be 15cm
Cable trench For multi cable in Vertical level: Min distance between two cable shall be 30cm.(min Sand cushioning at bottom of trench shall be 8cm +Cable+min Sand cushioning of 30cm+Cable+protective covering/Sand cushioning of 17cm above Cable)
Cable trench For LV/MV cable cushioning is not required where there is no possibility of mechanical damages.
Cable trench Extra loop of cable at end shall be 3mt for cable termination/Joints.

Cable Route

Cable Route Marker Cable Route Marker shall be min 0.5mt away from cable trench at the interval not exceeding 100mt parallel.
Cable Route Marker Plate Type Cable Route Marker shall be made of 100mmX5mm GI/Aluminum Plate welded/Bolted on 35mmX35mmX6mm Iron angle of 60cm Long.
Cable Route Marker Cement Concrete(C.C) type marker shall be made in formation of 1:2:4.

Cable Bending Radius

Cable Bending Radius Voltage      1Core          Unarmoured(Multi core)    Armoured(Multi core)                                                    11KV          20D                   15D                                        2D                                                                      22KV              20D                20D                                       15D 

 33KV              20D                25D                                      20D                                                   

Cable Tray (Perforated)

Cable Tray (Perforated) Cable Tray may be fabricated by two angle irons of 50mmX50mmX6mm as two longitudinal members with cross bracing between them 50mmX5mm welded/Bolted at angle and 1 mt spacing of 2mm thick MS sheet.

Overhead Line

Steel Tubular Pole 1/6 length of Steel Tubular Pole + 30 cm from base shall be coated with Black Bituminous paint on both internally and externally.

The remaining portion of the pole shall be painted with Red oxide.

Cross arm LV/MV Line: MS angle iron of size not less than  50mmX50mmX6mm(4.5kg/mt)                                                                 

11KV  Line: MS angle iron of size not less than 65mmX65mmX6mm(5kg/mt)

Cross arm LV/MV Line: MS Chanel iron of size not less than 75mmX40mmX4.8mm(7.14kg/mt)

11KV  Line: MS Chanel iron of size not less than 75mmX40mmX4.8mm(7.14kg/mt) 

Cross arm For LV/MV Line:

Min distance shall be 5cm between centre of insulation pin and end of cross arm.                                    

For 11KV Line:

Min distance shall be 10cm between center of insulation pin and end of cross arm.  

Cross arm Length Voltage        No of Horizontal Conductor        Length of Cross Arm                                                   LV/MV         2 Conductors                                   55cm                                                                              LV/MV          4 Conductors                                  115cm                                                                            LV/MV         4 Conductors Guard                         175 cm 

11KV            3 Conductors                                  225cm

Struts The Pit for Struts shall be located not less than 1.8mt from pole side. The depth of Pit shall be at least 1.2mt
Danger board All Support carrying HV Line shall be fitted with Danger Board( IS:2551) at height of 3mt.
Anti Climbing Device For HV Line(IS:278-1978) having 4Point Barbs 75mm+12mm apart weight 128/125 gm/mt shall be wrapped helically with pitch of 75mm around Limb of Pole height of 3.5mt to 5 to 6 mt.
Insulator For LV/MV Overhead Line: Pin/Shackle Insulator and For 11KV Line Pin/Disc Insulator
Insulator For Pin Insulator for LV/MV line:

 Stalk Length 135mm Shank Length 125 mm , min Load 2KN.                                                                  For Pin Insulator for 11KV  line:

Stalk Length 165mm Shank Length 150 mm ,min Load 2KN.

D Clamp D clamp shall be made of MS Flat size of 50mmX6mm,height of 75mm Galvanized and only used for vertical configuration for LV/MV Line only.
Pole Top Clamp Pole Top clamp made from Flat iron 50mmX8mm.
Stay wire Rod Stay wire Rod shall not be less than 1.8 m Long and 19mm Dia.Ankor Plate shall not be less than 45mmX45mmX7.5mm.
Overhead Conductor (min) For LV  Line :

AAC(All Alu.Cond) 7/1/2.21mm, ACSR 6/1/1/2.11mm, AAAC(All Alu.Alloy Cond) 7/2.09mm(20Sqmm)    

For 11KV/33KV   Line :

AAC(All Alu.Cond) N/A, ACSR 6/1/1/2.11mm, AAAC(All Alu.Alloy Cond) 7/2.56mm(30Sqmm)

Binding Wire Binding Wire with insulator shall be with 2.6mm(12SWG) soft aluminum wire.
Earthing in Overhead Line Earthing wire shall not be less than 4mm(8SWG) and min 3 earthling Pit per KM shall be required.

 If there is no Continuous wire for earthling in overhead line than each pole should be earthed.

Overhead Line Conductor Clearance(min)

Same Support For LV/MV Line on Same Support Vertical distance:

Between Phase to Earth shall be min 30cm and

Between Phase to Phase min 20cm

Same Support For LV/MV Line on Same Support  Horizontal distance:

Between Live wire on either side of support shall be 45cm.

Same Support For LV/MV Line on Same Support  Horizontal distance:

Between Live wire on same side of support shall be 30cm.

Same Support For LV/MV Line on Same Support Horizontal distance:

 Between central of pin insulator to end of cross Arm shall be 05cm.

Same Support For HV Line In Triangular Configuration for 11KV/33KV Line shall be min 1.5mt.
Different Voltage When Two conductor of different Voltage are erected on same support min clearance between LV/MV and 11KV shall be min 1mt.
Different Support A Clearance not less than height of tallest support may be maintained between parallel overhead line on Different support.
Different Support When Two overhead line cross each other vertical clearance between LV/MV and 11KV shall not be less than 1.25mt and for LV/MV and 33KV line shall be not less than 2mt.
Across Road Min Conductor Clearance across Road:

For LV/MV Line is 5.8mt and for HV Line 6.1mt

Along Road Min Conductor Clearance along Road:

For LV/MV Line is 5.5mt and for HV Line 5.8mt

Along/Across Min Conductor Clearance along/across Road:

For LV/MV/HV up to 11Kv (Bare Cond) Line is 4.6mt.                                    

Min Conductor Clearance along/across Road:

For LV/MV/HV up to 11Kv (Insulated Cond) Line is 4.0mt.                            

Min Conductor Clearance along/across Road:

 For HV (11Kv To 33Kv) Line is 5.2mt.                                                          

Min Conductor Clearance along/across Road:

 For EHV (above 33Kv) is 5.2mt + 0.3 mt for every 33KV(Not Less than 6.1).

From Building Min Conductor Vertical Clearance above Building:

For LV/MV Line is 2.5mt from highest Point.                                            

Min Conductor Horizontal Clearance near Building:

For LV/MV Line is 1.5mt from nearest Point.                                        

Min Conductor Vertical Clearance above Building:

 For MV/EHV(up to 33KV)  Line is 3.7mt from highest Point.                                          

Min Conductor Vertical Clearance above Building:

 For MV/EHV(above 33KV)  Line is 3.7mt + 0.3mt for every 33KV                                                                                                                                                                 Min Conductor Horizontal Clearance above Building:

For MV/EHV(Up to 11KV)  Line is 1.2mt.                                             

Min Conductor Horizontal Clearance above Building:

For EHV(Up to  33KV)  Line is 02mt.                                                     

Min Conductor Horizontal Clearance above Building:

For EHV(above  33KV)  Line is 2mt + 0.3mt for every 33KV

Looping Box

Looping Box Looping Bus shall be fabricated from MS Sheet of 1.6mm(16SWG) thickness, Min Size 250mmX200mmX100mm for single cable entry and for 250mmX300mmX100mm for more than two cable entry

Feeder Pillar

Feeder Pillar Feeder Pillar shall be fabricated min 2mm thick MS sheet and hinged type double door at front side. If width of Pillar shall be less than 60cm than single hinged type door shall be permitted.
Feeder Pillar Min height of Pedestal of Feeder Pillar shall be not less than 45cm and 1 to 2 mt height from Road Level.
Feeder Pillar Each Feeder Pillar shall be earthed with 2 no of Earthing electrode.

Substation

Area of S/S S/S                TC Room Area      Total S.S Area(T.C,HT/LT Panel, without DG)                                      2X500KVA     36 Sq.meter            130 Sq.meter                                                                                       3X500KVA     54 Sqmeter             172 Sq.meter                                                                                           2X800KVA     39 Sqmeter             135 Sq.meter                                                                                       3X800KVA    58 Sqmeter             181 Sq.meter                                                                                        2X1000KVA   39 Sqmeter             149 Sq.meter                                                                                           2X1000KVA   58 Sqmeter             197 Sq.meter

 

 

 

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