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.

(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

  • 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
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