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

 

Electrical Thumb Rule- High Rise Building (As per NBC)


 

Luminous Efficacy, Life, Lumen Maintenance and Color Rendition (Table-8) NBC
Light Source  Wattage Efficacy (lm/W ) Average Life Maintenance Color Rendition
Incandescent lamps  15 to 200  12 to 20  500 to 1000  Fair to good  Very good
Tungsten halogen     300 to 1500  20 to 27  200 to 2000  Good to very good  Very good
Standard fluorescent lamps       20 to 80 55 to 65 5000 Fair to good  Good
Compact fluorescent lamps (CFL)       5 to 40  60 to 70 7500 Good Good to very good
Slim line fluorescent      18 to 58 57 to 67 5000  Fair to good Good
High pressure mercury vapor lamps      60 to 1000  50 to 65 5000  Very low to fair  Federate
Blended – light lamps    160 to 250  20 to 30 5000 Low to fair  Federate
High pressure sodium vapor lamps  50 to 1000  90 to 125  10000 to 15000  Fair to good  Low to good
Metal halide lamps       35 to 2000  80 to 95 4000 to 10000 Very low  Very good
Low pressure sodium       10 to 180 100 to 200 10000 to 20000 Good to very good  Poor
LED  0.5 to 2.0  60 to 100  10000 Very good  Good for white LED

 

Approximate Cable Current Capacity

Cable Size Current Capacity MCB Size
1.5 Sq.mm 7.5 To 16 A 8A
2.5 Sq.mm 16 To 22 A 15A
4 Sq.mm 22 To 30 A 20A
6 Sq.mm 39 To 39 A 30A
10 Sq.mm 39 To 54A 40A
16 Sq.mm 54 To 72A 60A
25 Sq.mm 72 To 93A 80A
50 Sq.mm 117 To 147A 125A
70 Sq.mm 147 To 180A 150A
95 Sq.mm 180 To 216A 200A
120 Sq.mm 216 To 250A 225A
150 Sq.mm 250 To 287A 275A
185 Sq.mm 287 To 334A 300A
240 Sq.mm 334 To 400A 350A

 

Requirements  for  Physical  Protection  of Underground Cables  (As per NBC)

Protective  Element Specifications
Bricks  (a) 100 mm minimum  width 
(b) 25 mm thick 
(c) sand cushioning 100  mm  and  sand  cover 100 mm 
Concrete slabs At least 50 mm thick
Plastic  slabs (polymeric cover  strips) Fiber  reinforced plastic depending on properties  and has to be matched with the protective cushioning and cover
PVC  conduit  or  PVC  pipe  or stoneware  pipe or Hume pipe The  pipe  diameter should  be  such  so  that the  cable  is  able  to easily slip down the pipe
Galvanized pipe  The  pipe  diameter should  be  such  so  that the  cable  is  able  to easily slip down the pipe
The trench shall be back filled to cover the cable initially by 200 mm of sand fill; and then a plastic marker strip  hall be put over the full length of cable in the trench.
The marker signs shall be provided where any cable enters or leaves a building. This will identify that there is a cable located underground near the building.
 The trench shall then be completely filled. If the cables rise above ground to enter a building or other structure, a mechanical protection such as a GI pipe or PVC pipe for the cable from the trench depth to a height of 2.0 m above ground shall be provided.

 

AREA REQUIRED FOR GENERATOR IN ELECTRIC SUBSTATION (As per NBC)

Capacity  kVA Area m2 Clear Height below the Soffit of the Beam m
25 56 3.6
48 56 3.6
100 65 3.6
150 72 3.6
248 100 4.2
350 100 4.2
480 100 4.2
600 110 4.6
800 120 4.6
1010 120 6.5
1250 120 6.5
1600 150 6.5
2000 150 6.5

 

Low Voltage Cabeling for Building (As per NBC)

Low Voltage Cable Cables/wires, such as fiber optic cable, co-axial cable, etc. These shall be laid at least at a distance of 300 mm from any power wire or cable. The distance may be reduced only by using completely closed earthed metal trucking with metal separations for various kind of cable. Special care shall be taken to ensure that the conduit runs and wiring are laid properly for low voltage signal to flow through it.
The power cable and the signal or data cable may run together under floor and near the equipment. However, separation may be required from the insulation aspect, if the signal cable is running close to an un-insulated conductor carrying power at high voltage. All types of signal cables are required to have insulation level for withstanding 2 kV impulse voltages even if they are meant for service at low voltage.
Conduit Color Scheme Power conduit=Black
Security conduit=Blue
Fire alarm conduit=Red
Low voltage conduit=Brown
UPS conduit Green

 

Sub Station Guideline (As per NBC)

Substation Location Location of substation in the basement should be avoided, as far as possible.
If there is only one basement in a building, the substation/switch room shall not be provided in the basement and the floor level of the substation shall not be lowest point of the basement.
Substation shall not be located immediately above or below plumbing water tanks or sewage treatment plant (STP) water tanks at the same location
Substation Door/Shutter All door openings from substation, electrical rooms, etc, should open outwards
Vertical shutters (like rolling shutters) may also be acceptable provided they are combined with a single leaf door opening outwards for exit in case of emergency
For large substation room/electrical  room  having  multiple equipment,  two  or more  doors  shall  be provided which shall be remotely located from each other
No services or ventilation shafts shall open into substation or switch room unless specific to substation or switch room
Transformer Location In case of HV panel and transformers located at different floors or at a distance more than 20 m, HV isolator shall be  provided  at transformer end
In case transformer and main MV/LV panel room are located at different floors or are at a distance more than 20 m, MV/LV isolator shall be provided at  transformer  end
In  case  of  two  transformers  (dry  type  or transformers with oil quantity less than 2 000 liter)  located  next  to  each  other without intermittent wall, the distance between the two shall  be minimum  1 500 mm  for  11  kV, minimum 2 000 mm for 22 kV and minimum 2 500 mm for 33 kV. Beyond 33 kV, two transformers shall be separated by baffle wall of 4 h fire rating.
If dry type transformer is used, it may be located adjacent to medium voltage switchgear in the form of unit type substation. In such a case, no separate room or fire barrier for the transformer is required either between transformers or between transformer and the switchgear, thereby decreasing the room space requirement; however, minimum distances as specified.
Oil Filled Equipment (Transformer / C.B) Substations with oil-filled equipment/apparatus transformers and high voltage panels shall be either located in open or in a utility building
They shall not be located in any floor other than the ground floor or the first basement of a utility building  not be located below first basement slab of utility building.
They shall have direct access from outside the building for operation and maintenance of the equipment.
It shall be separated from the adjoining buildings including the main building by at least 6 m clear distance to allow passage of fire tender between the substation/utility building and adjoining building/main building.
Substation equipment having more than 2 000 liter of oil whether located indoors in the utility building or outdoors shall have  baffle walls  of  4  h  fire  rating between apparatus.
Provision of  suitable oil soak-pit, and where use of more than 9 000 liter of oil in any one oil tank, receptacle or chamber is involved, provision shall be made for the draining away or removal of any oil which may leak or escape from the tank, receptacle or chamber containing the same
Power Supply Voltage supply  is  at  240  V  single  phase  up  to  5  kVA, 415/240 V 3-phase from 5 kVA to 100 kVA, 11 kV (or 22 kV) for loads up to 5 MVA and 33 kV or 66 kV for consumers of connected load or contract demand more than 5 MVA.
In case of connected load of 100 kVA and above, the relative advantage of high voltage three-phase supply should be considered.
In case of single point high voltage metering, energy meters shall  be  installed  in  building  premise,such a place which is readily accessible to the owner/operator of the building and the Authority. The supplier or owner of the installation shall provide at the point of commencement of supply a suitable isolating device fixed in a conspicuous position at not more than 1.7 m above the ground so as to completely isolate the supply to the building in case of emergency
Trench Drain In case of cable trench in substation/HV switch room/MV switch room, the same shall be adequately drained to ensure no water is stagnated at any time with live cables.

 

Fence for Substation Enclose any part of the substation which is open to the air, with a fence (earthed efficiently at both ends) or wall not less than 1800 mm (preferably not less than 2400 mm) in height

 

HV Distribution in Building The power supply HV cables voltage shall not be more than 12 kV and a separate dedicated and  fire  compartmented  shaft  should  be provided for carrying such high voltage cables to upper floors in a building. These shall not be mixed with any other shaft and suitable fire detection and suppression measures shall be provided throughout the length of the cable on each floor.

 

Switch Room / MV switch room Switch room / MV switch room shall be arrived at considering 1200 mm clearance requirement from top of the equipment to the below of the soffit of the beam .In case cable entry/exit is from above the  equipment  (transformer,  HV switchgear, MV  switchgear),  height  of substation room/HV switch room/MV switch room shall also take into account requirement of space for turning radius of cable above the equipment height.

 

 

 

 

 

Calculate Motor Pump Size


  • Calculate Size of Pump having following Details
  • Static Suction Head(h2)=0 Meter
  • Static Discharge Head (h1)=50 Meter.
  • Required Amount of Water (Q1)=300 Liter/Min.
  • Density of Liquid (D) =1000 Kg/M3
  • Pump Efficiency (pe)=80%
  • Motor Efficiency(me)= 90%
  • Friction Losses in Pipes (f)=30%

Calculations:

  • Flow Rate (Q) =Q1x1.66/100000 =300×1.66/100000= 0.005 M3/Sec
  • Actual Total Head (After Friction Losses) (H) = (h1+h2)+((h1+h2)xf)
  • Actual Total Head (After Friction Losses) (H)=50+(50×30%)= 65 Meter.
  • Pump Hydraulic Power (ph) = (D x Q x H x9.87)/1000
  • Pump Hydraulic Power (ph) = (1000 x 0.005 x 65 x9.87)/1000 =3KW
  • Motor/ Pump Shaft Power (ps)= ph / pe = 3 / 80% = 4KW
  • Required Motor Size: ps / me =4 / 90% = 4.5 KW
  • Required Size of Motor Pump = 4.5 HP or 6 HP

Calculate Size of Cable for Motor (As NEC)


NEC Code 430.22 (Size of Cable for Single Motor):

  • Size of Cable for Branch circuit which has Single Motor connection is 125% of Motor Full Load Current Capacity.
  • Example: what is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power Factor. Full-load currents for 5 hp = 7Amp.
  • Min Capacity of Cable= (7X125%) =8.75 Amp.

 NEC Code 430.6(A) (Size of Cable for Group of Motors or Elect. Load).

  • Cables or Feeder which is supplying more than one motors other load(s), shall have an ampacity not less than 125 % of the full-load current rating of the highest rated motor plus the sum of the full-load current ratings of all the other motors in the group, as determined by 430.6(A).
  • For Calculating minimum Ampere Capacity of Main feeder and Cable is 125% of Highest Full Load Current + Sum of Full Load Current of remaining Motors.
  • Example:what is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power Factor, 1 No of 10 hp, 415-volt, 3-phase motor at 0.8 Power Factor, 1 No of 15 hp, 415-volt, 3-phase motor at 0.8 Power Factor and 1 No of 5hp, 230-volt, single-phase motor at 0.8 Power Factor?
  • Full-load currents for 5 hp = 7Amp.
  • Full-load currents for 10 hp = 13Amp.
  • Full-load currents for 15 hp = 19Amp.
  • Full-load currents for 10 hp (1 Ph) = 21Amp.
  • Here Capacity wise Large Motor is 15 Hp but Highest Full Load current is 21Amp of 5hp Single Phase Motor so 125% of Highest Full Load current is 21X125%=26.25Amp
  • Min Capacity of Cable= (26.25+7+13+19) =65.25 Amp.

 NEC Code 430.24 (Size of Cable for Group of Motors or Electrical Load).

  • As specified in 430.24, conductors supplying two or more motors must have an ampacity not less than 125 % of the full-load current rating of the highest rated motor +  the sum of the full-load current ratings of all the other motors in the group or on the same phase.
  •  It may not be necessary to include all the motors into the calculation. It is permissible to balance the motors as evenly as possible between phases before performing motor-load calculations.
  • Example:what is the minimum rating in amperes for conductors supplying 1No of 10 hp, 415-volt, 3-phase motor at 0.8 P.F and 3 No of 3 hp, 230-volt, single-phase motors at 0.8 P.F.
  • The full-load current for a 10 hp, 415-volt, 3-phase motor is 13 amperes.
  • The Full-load current for single-phase 3 hp motors is 12 amperes.
  • Here for Load Balancing one Single Phase Motor is connected on R Phase Second in B Phase and third is in Y Phase.Because the motors are balanced between phases, the full-load current on each phase is 25 amperes (13 + 12 = 25).
  • Here multiply 13 amperes by 125 %=(13 × 125% = 16.25 Amp). Add to this value the full-load currents of the other motor on the same phase (16.25 + 12 = 28.25 Amp).
  • The minimum rating in amperes for conductors supplying these motors is 28 amperes.

 NEC 430/32 Size of Overload Protection for Motor:

  • Overload protection (Heater or Thermal cut out protection) would be a device that thermally protects a given motor from damage due to heat when loaded too heavy with work.
  • All continuous duty motors rated more than 1HP must have some type of an approved overload device.
  • An overload shall be installed on each conductor that controls the running of the motor rated more than one horsepower. NEC 430/37 plus the grounded leg of a three phase grounded system must contain an overload also. This Grounded leg of a three phase system is the only time you may install an overload or over – current device on a grounded conductor that is supplying a motor.
  • To Find the motor running overload protection size that is required, you must multiply the F.L.C. (full load current) with the minimum or the maximum percentage ratings as follows;

Maximum Overload

  • Maximum overload = F.L.C. (full load current of a motor) X allowable % of the maximum setting of an overload,
  • 130% for motors, found in NEC Article 430/34.
  • Increase of 5% allowed if the marked temperature rise is not over 40 degrees or the marked service factor is not less than 1.15.

Minimum Overload

  • Minimum Overload = F.L.C. (full load current of a motor) X allowable % of the minimum setting of an overload,
  • 115% for motors found in NEC Article 430/32/B/1.
  • Increase of 10% allowed to 125% if the marked temperature rise is not over 40 degrees or the marked service factor is not less than 1.15

 

How to Design efficient Street lighting-(Part-6)


(3) Light trespass:

  • Light trespass is condition when spill (Unwanted or Unneeded) light from a streetlight or floodlight enters a window and illuminates an indoor area.

 How to Reduce Trespass

  • Select luminaries, locations, and orientations to minimize spill light onto adjacent properties.
  • Use well-shielded luminaries.
  • Keep floodlight aiming angles low so that the entire beam falls within the intended lighted area.

 Difference between full cutoffs and fully shielded:

  • The full cutoff has is luminaries that have no direct up light (no light emitted above horizontal) and 10% of light intensity between 80° and 90°.
  • The term full cutoff is often substituted for the term fully shielded.
  • The both terms are not equivalent. Fully shielded luminaires emit no direct up light, but have no limitation on the intensity in the region between 80° and 90°
  • Luminaires that are full cutoff, cutoff, semi cutoff, and non cutoff , may also qualify as fully shielded.

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  • There is also a confusing assumption that a luminaire with a flat lens qualifies as a full cutoff luminaries. While this may be true or not in some Lighting Fixtures case.

1

  • Fully shielded means, a lighting fixture constructed in such a manner that the bulb should be fully recessed into Fixture so that all light is directed downward below the horizontal.
  • The fixture is angled so the lamp is not visible below the barrier (no light visible below the horizontal angle).

(G) Selection of Luminas:

(1) Types of Lighting Source

  • Street Lights are mostly Low-pressure sodium (LPS), High-pressure sodium (HPS), Metal halide and Light emitting diodes (LED).
  • LPS is very energy efficient but emits only a narrow spectrum of pumpkin-colored light that some find to be undesirable.
  • LPS is an excellent choice for lighting near astronomical observatories and in some environmentally sensitive areas.
  • HPS is commonly used for street lighting in many cities. Although it still emits an orange-colored light, its coloring is more “true to life” than that of LPS.
  • Where it’s necessary to use white light, there are metal halide and LEDs.

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  • High-pressure sodium lamps should be used for expressways, main roads, secondary roads and branch roads.
  • Low-power metal halide lamps should be used in mixed traffic roads for motor vehicles and pedestrians in residential areas.
  • Metal halide lamps can be used for motor vehicle traffic, such as city centers and commercial centers, which require high color identification.
  • Metal halide lamps, CFL lamps are used at Pedestrian streets in industrial areas, sidewalks in residential areas, and sidewalks on both sides of motorway traffic.
  • LED streetlights are more durable, longer lasting, efficiency, dimmable capacity and cost effective than traditional lights.
  • LED also enhances public safety by delivering superior visible light while providing the environmental advantage of using less energy.

 (2) Color Rendering Index (CRI):

  • CRI Measures the ability of the artificial light to show or reproduce the colors of the road or objects on the road, relative to a natural light source.
  • The natural light source (the sun) has CRI of 100. The higher
  • This index the better the visibility will be. For all types of road CRI ≥ 70 is recommended.

(3) Efficacy

  • At the low end LED efficacy starts at 70 lumens per watt (lm/W) and reaches as high as 150 lm/W.
  • While the mean efficacy for outdoor area fixtures is slightly lower than common indoor fixtures such as troffers and linear lighting about 100 lm/W for area lights compared to about 110 lm/W for troffers and linear fixtures this difference is not significant. It may be the result of outdoor area lights requiring more precise luminous intensity distributions and other factors unique to outdoor lighting.

(4) Fixture Protection:

  • When using sealed road lighting, the protection level of the light source cavity should not be lower than IP54.
  • For roads and places with dangerous environmental pollution and heavy maintenance, the protection level of the light source cavity should not be lower than IP65.
  • The degree of protection of the lamp electrical appliance cavity should not be lesser than IP43.
  • Lamps with excellent corrosion resistance should be used in areas or places with high levels of corrosive gases such as acid and alkali in the air.

(H) Effective Road Lighting:

  • Sufficient illumination.
  • Good uniformity.
  • No Glare.
  • Low consumption.
  • No Color Temperature abnormalities
  • No Zebra effect
  • Shielded lighting to ensure light is pointed downwards
  •  Completely uniform illuminance.
  • No requirement for over lighting to obtain sufficient average illumination.
  • Absence of glare.
  • Absence of low angle radiation that causes sky glow.
  • Control of light trespass.
  • High redundancy.

 Effective Lightning

Features Benefits
Proper pole height & spacing  Provide uniform light distribution
Proper Luminaire aesthetics  Blends in with the surroundings
Good maintenance Reduce problems in lightning
High lamp efficiency  Minimize energy cost
Life of Luminaire Reduce lamp replacement cost
Good color rendering  Helps object appear more natural
Proper light distribution  Provide required light on roads
Cost effectiveness  Lowers operating cost
Minimizing light pollution & glare  Reduce energy use

 

Effective Energy-efficient Street Lighting Systems (NYSERDA, 2002)

Features Benefits
Proper pole height and spacing Provides uniform light distribution, which improves appearance for safety and security Meets recommended light levels Minimizes the number of poles, reducing energy and maintenance costs
Proper luminaire aesthetics Blends in with the surroundings
High lamp efficacy and Luminaire efficiency Minimizes Energy cost
Life of the luminaire and other components Reduces lamp replacement costs
Cost effectiveness Lowers operating cost
High Lumen Maintenance Reduces lamp replacement costs
Good color rendering Helps object appear more natural and pleasing to the public Allows better recognition of the environment, improves security
Short lamp Re strike Allows the lamp to quickly come back after a power interruption
Proper light distribution Provides required light on the roads and walkways
Proper Cutoff Provides adequate optical control to minimize light pollution
Minimizing light pollution and Glare Reduces energy use
Automatic Shutoff Saves energy and maintenance costs by turning lamps off when not needed

 

Minimum Value of Street Light Designing

Descriptions Min Value
Watt 400
Lumens Per Watt 80 To 140
Voltage 230Volt
Frequency 50 To 60Hz
Power Factor   More than 95
THD  < 20%
Life Hours 70,000 hours
Color Temperature 4000K  To  5000K
CRI More than 75
Beam Angle / Beam Pattern  Type 2,3,4,5
Operating Temperature (-)25°C To (+)50°C
Working Humidity 10% To 90% RH
IP Rating  IP67
Dimmable 0-10V
Optic Lens Material High Polycarbonate (PMMA)
Forward Current >600mA
Housing IP65 – Aluminum Alloy and PC Lens
Dimension  18.23″ X 13.58″ X 4.57″
Weight  15.30 lbs – 34.39 lbs
Warranty 10 Years

How to Design efficient Street lighting-(Part-5)


(2) Surround Ratio (SR):

  • Road lighting should be illuminate not only the road, but also the adjacent areas so motorists can see objects in the periphery and anticipate potential road obstructions (e.g., a pedestrian about to step onto the road).
  • The SR is the visibility of the road’s periphery relative to that of the main road itself.
  • As per industry standards, SR should be at least 50.
  • Figure show how road lighting should illuminate both the main road and its periphery.

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(F) Lighting Pollutions

  • Light pollution is an unwanted consequence of outdoor lighting and includes such effects as sky glow, light trespass, and glare. 
  • 30 to 50% of all light pollution is produced by roadway lighting that shines wasted light up and off target.

(1) Glare:

  • Glare is the condition of vision in which there is discomfort or a reduction in the ability to see significant objects. Glare affects human vision and it is subdivided into four components, Disability Glare, Discomfort Glare, Direct Glare and Indirect Glare.
  • By origin
  1. Direct Glare
  2. Indirect (reflected) Glare
  • By effect on people
  1. Disability Glare
  2. Discomfort Glare
  • Disability glare:
  • Disability glare is the glare that results in reduced visual performance and visibility.
  • Since disability glare reduces the ability to perceive small contrasts.
  • It can impair important visual tasks in traffic such as detecting critical objects, controlling headlights, and evaluating critical encounters, making glare a potential danger for road users.
  • LED light sources can provide very high luminance lev­els which may cause glare. For this reason, LED lamps are commonly equipped with diffusers to reduce this luminance.
  • Disability glare may vary for dif­ferent individuals and it can be calculated objectively.
  • In a particu­lar illuminated environment, the human eye will be able to detect differences in luminance down to a certain threshold. This threshold can be compared for a situa­tion in the same environment when a source of glare is added. By comparing these thresholds, the threshold increment can be derived.
  • Discomfort glare:
  • Discomfort glare is the glare producing discomfort. It does not necessarily interfere with visual performance or visibility.
  • As vertical light angles increase, discomforting glare also increases
  • Discomfort glare, on the other hand, is a subjective phenomenon and there is no method for its Rating.
  • Although the 9-point De Boer scale (ranging from “1” for “unbearable” to “9” for “unno­ticeable”) is the most widely used in the field of auto­motive and public lighting.
  • Direct Glare:
  • Direct glare is caused by excessive light entering the eye from a bright light source. The potential for direct glare exists anytime one can see a light source. With direct glare, the eye has a harder time seeing contrast and details.
  • A system designed solely on lighting levels, tends to aim more light at higher viewing angles, thus producing more potential for glare.
  • Exposed bright light source, for example a dropped lens cobra head or floodlight causes of direct glare.
  • Direct glare can be minimized with careful equipment selection as well as placement.

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  • Figure illustrates two examples of exterior lighting that results in glare.

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  • Fig shows how full cutoff luminaries (Shielded Luminaires) can minimize this direct glare. In exterior applications, use fully shielded luminaires that directs light downwards towards the ground.
  • Indirect Glare: Indirect glare is caused by light that is reflected to the eye from surfaces that are in the field of view – often in the task area.
  • Indirect Glare can be minimized with the type and layout of lighting equipment. Direct the light away from the observer with the use of low glare, fully shielded luminaries.
  • As the uniformity ratio increases (poor uniformity), object details become harder to see.
  • For roadway lighting, good uniformity shows evenly lighted pavement. However, to meet small target visibility criteria, a non uniform roadway surface may be better.
  • There should be a balance between uniform perception and detecting objects on the road. Also, emphasis is put on horizontal surface uniformity. In reality, vertical surfaces may require more lighting in order to improve guidance.

How to Reduce Glare:

  • Glare and light trespass are more concern when installing floodlights.
  • Use shielded Light should be use to reduce Glare.
  • Higher mounting heights can more effective in controlling spill light, because floodlights with a more controlled light distribution (i.e., narrower beam) may be used, and the floodlights may be aimed in a more downward direction, making it easier to confine the light to the design area.
  • Lower mounting heights increase the spill light beyond the property boundaries. To illuminate the space satisfactorily, it is often necessary to use floodlights with a broader beam and to aim the floodlights in directions closer to the horizontal than would occur when using higher mounting heights.
  • Lower mounting heights make bright parts of the floodlights more visible from positions outside the property boundary, which can increase glare.

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(2) Sky glow:

  • Sky Glow is brightening of the night sky caused by outdoor lighting.
  • Light that is emitted directly upward by luminaries or reflected from the ground is scattered by dust and gas molecules in the atmosphere, producing a luminous background. It has the effect of reducing one’s ability to view the stars in Night.

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How to Reduce Sky Glow

  • While it is difficult to accurately model sky glow, at this point it is presumed that the most important factors are light output and lamp spectral characteristics, light distribution from the luminaire, reflected light from the ground, and aerosol particle distribution in the atmosphere.
  • If the quantity of light going into the sky is reduced, then sky glow is reduced. Thus, to reduce sky glow by
  • By using full cutoff luminaires to minimize the amount of light emitted upward directly from the luminaire.
  • Reduce Lighting Level.
  • Make practice to Turn off unneeded lights
  • Limited Lighting hours in outdoor sales areas, parking areas, and signages
  • Installing Low-Pressure Sodium light sources, which allow astronomers to filter the line spectra from telescopic images.

How to Design efficient Street lighting-(Part-4)


(C) Lighting Factor:

(1) Maintenance Factor (Light Loss Factors) (MF)

  • The Maintenance Factor (Light loss factor) is the combination of factors used to denote the reduction of the illumination for a given area after a period of time compared to the initial illumination on the same area.
  • The efficiency of the luminaire is reduced over time. The designer must estimate this reduction to properly estimate the light available at the end of the lamp maintenance life.
  • Luminaire maintenance factors vary according to the intervals between cleaning, the amount of atmospheric pollution and the IP rating of the luminaire.
  • However, it is proposed to consider maintenance factor of not less than 0.5 for LED Road lighting installations for IP66 rated luminaires.
  • The maintenance factor may range from 0.50 to 0.90, with the typical range between 0.65 To 0.75
  • These maintenance factor values shall be adopted for the purposes of producing the lighting simulation design.
  • The maintenance factor is the product of the following factors.
  • LLF = LLD x LDD x EF
  • Mostly We consider Maintenance factor from 0.8 to 0.9
  • We have to choose Maintenance factor carefully by increasing maintenance factor 0.5 the spacing of pole increasing 2 meter to 2.5 meter.
Maintenance Factor Max. Spacing of Pole (Meter)
0.95 43
0.9 40.5
0.85 38
0.8 36

(A) Lamp Lumen Depreciation Factor (LLD)

  • As the lamp progresses through its service life, the lumen output of the lamp decreases. This is an inherent characteristic of all lamps. The initial lamp lumen value is adjusted by a lumen depreciation factor to compensate for the anticipated lumen reduction.
  • This assures that a minimum level of illumination will be available at the end of the assumed lamp life, even though lamp lumen depreciation has occurred. This information should be provided by the manufacturer. For design purposes, a LLD factor of 0.9 to 0.78 should be used.

(B) Luminaire Dirt Depreciation Factor (LDD).

  • Dirt on the exterior and interior of the luminaries and to some on the lamp reduces the amount of light reaching the roadway.
  • Various degrees of dirt accumulation may be anticipated depending upon the area in which the luminaire is located. Industry, exhaust of vehicles, especially large diesel trucks, dust, etc, all combine to produce the dirt accumulation on the luminaries.
  • Higher mounting heights, however, reduce the vehicle-related dirt accumulations.
  • LDD factor of 0.87 to 0.95 should be used. This is based on a moderately dirty environment and three years exposure time.

(C) Equipment Factor (EF).

  • Allows for variations inherent in the manufacture and operation of the equipment (i.e., luminaries, system voltage and voltage drop).
  • It is generally assumed to be 95%.

(2) Coefficient of Utilization (CU):

  • Coefficient of Utilization is the ratio of the luminous flux from a luminaire received on the surface of the roadway to the lumens emitted by the luminaire’s lamps alone.
  • Coefficient of Utilization should be maximum.
  • Coefficient of Utilization differs with each luminaire type, and depends upon mounting height, road width, and overhang.
  • The coefficient of utilization (K) should be over 30% or the utilance above 40% for the road, highway, square or enclosure. Luminaires or floodlights should not by placed far from the area to be lit or, where appropriate, light projection beyond the useful zone should be minimized (K = average maintained illuminance multiplied by the surface calculation and divided by the lumens installed).

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Type Luminaries Dirt Depreciation Luminaire Lumen Depreciation Total Light Loss Factor
LED 0.9 0.85 0.765
HPS 0.9 0.9 0.81
LPS 0.9 0.85 (0.7 for 180W) 0.765 (0.63 for 180W)

 

Light Loss Factors

Type of Lamp Laminar Dirt description Light Loss Factor
HPS 0.88 0.74
Induction 0.88 0.62
LED 0.88 0.72

 

Maintenance factors

Cleaning intervals (months) Pollution category
High Medium Low
12 0.53 0.62 0.82
18 0.48 0.58 0.8
24 0.45 0.56 0.79
36 0.42 0.53 0.78

 

Maintenance Factors for 36 month cleaning interval

Factors IP5X IP6X
Pollution category Pollution category
Low Medium High Low Medium High
LMF 0.88 0.82 0.76 0.9 0.87 0.83
LLMF 0.89 0.89 0.89 0.89 0.89 0.89
MF 0.78 0.73 0.68 0.80 0.77 0.74

 (E) Lighting Uniformities

(1) Lighting Uniformities

  • Uniformity is a description of the smoothness of the lighting pattern or the degree of the intensity of bright and dark areas on the road.
  • Uniformity is a measure of how evenly distributed the light on the road is, which can be expressed as Overall Uniformity (UO) and Longitudinal Uniformity (UL).
  • The uniformity ratio shall not exceed 4:1 and preferably should not exceed 3:1 except on residential streets, where 6:1 may be acceptable.

(A) Overall uniformity:

  • In design, the overall uniformity (UO) is expressed as a ratio of the minimum to the average luminance on the road surface of the carriageway within the calculation area.
  • UO=Lmin / Lave

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  • It is a measure of how evenly or uniformly illuminate on the road surface.
  • A good overall uniformity ensures that all spots and objects on the road are sufficiently lit and visible to the motorist.
  • The industry accepted value for UO is 30 to 0.40.

(B) Longitudinal uniformity:

  • The longitudinal uniformity (UL) is expressed as the ratio of the minimum to maximum luminance along the center line of a lane within the calculation area.
  • UL=Lmin / Lmax.
  • Longitudinal uniformity is a measure to reduce bright and dark bands of light appearing on road lit surfaces. The effect can be somewhat hypnotic and present confusing luminance patterns.

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  • It is a measure to reduce the intensity of bright and dark banding on road lit surface.
  • A good level of longitudinal uniformity ensures comfortable driving conditions by reducing the Pattern of high and low luminance levels on a road (i.e. zebra effect).
  • It is applicable to long continuous roads.

 Combination of Overall Uniformity and Longitudinal Uniformity:

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  • The picture on the left shows a road with good UO while the picture on the right has low level of UO. The Road is more visible in the road with higher UO. Having higher UO allows the motorist to see the road clearly and anticipate potential road hazards (e.g. open manholes, road excavations, sharp objects on the road, people crossing the street).
  • The picture on the right shows a road with low level of UL demonstrating the ‘Zebra Effect’ while the picture on the left has high level of UL without ‘Zebra Effect’.
  • The ‘zebra effect’ can cause discomfort to motorists, posing a risk to road safety. Ensuring good level of uniformity can reduce the luminance level needed. 
Lighting levels
Category Eave ( LUX) Emin  LUX) Uniformity ratios
Emax : Emin Eave : Emin
Express & Main street 30 15 3:01 2.5:1
Suburban shopping street 25 10 5:01 3:01
Subsidiary street 15 10 5:01 3:01
Other streets 15 5 10:01 5:01

 

Road Classification Area Classification Average  Lux Uniformity Ratio (Aver./Min.)
Arterial (Minor & Major) Commercial 12 3 to 1
Intermediate 9
Residential 6
Collector (Minor & Major) Commercial 8
Intermediate 6 4 to 1
Residential 4
Local Commercial 6
Intermediate 5 6 to 1
Residential 3
Alleys Commercial 4
Intermediate 3 6 to 1
Residential 2
Sidewalks (Roadside) Commercial 3 3 to 1
Intermediate 6 4 to 1
Residential 2 6 to 1
Pedestrian Ways 15 3 to 1

  

Illumination for Intersections

Functional Classification Average Maintained Illumination at Pavement by Pedestrian Area Classification in Lumen Uniformity
High Medium Low Eavg/Emin
Major/Major 37 28 19 32
Major/Collector 31 24 16 32
Major/Local 28 22 14 32
Collector/Collector 26 19 16 43
Collector/Local 23 17 11 43
Local/Local 19 15 9 65

 

Illumination for Pedestrian Areas

Maintained Illuminance Values for Walkways
Area Classification Description E avg (Lux) EV min (Lux) E avg/Emin
High Pedestrian Conflict Mixed Vehicle and Pedestrian 22 11 43
Areas Pedestrian Only 11 5 43
Medium Pedestrian Pedestrian Areas 5 2 43
Conflict Areas
Low Pedestrian Rural/Semi-Rural Areas 2 1 108
Conflict Areas Low Density Residential (2 or fewer dwelling units per acre) 3 1 65
Medium Density Residential (2.1 to 6.0 dwelling units per acre) 4 1 43
Pedestrian Portion of Pedestrian/Vehicular Underpasses Day 108 54 43
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