277 VOLT LIGHTING
- Thread starter kiss
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dana1028
Senior Member
- Location
- San Francisco Bay area
Re: 277 VOLT LIGHTING
Flourescent fixtures are computed on the total ampere rating of the units (ballasts) and not on the watts of the lamps. [220.4(B)]
Check your ballasts.
Flourescent fixtures are computed on the total ampere rating of the units (ballasts) and not on the watts of the lamps. [220.4(B)]
Check your ballasts.
Re: 277 VOLT LIGHTING
4432/(rated input wattage of ballast)=# of fixtures on circuit.
4432=16A*277V
I like to circuit less than the 16A allowed so that when any fixtures are added or the rated wattage is increased(on a substitute fixture) will not require new cicruiting. I like to use 13A as a max but that is a design item, code says 16A.
4432/(rated input wattage of ballast)=# of fixtures on circuit.
4432=16A*277V
I like to circuit less than the 16A allowed so that when any fixtures are added or the rated wattage is increased(on a substitute fixture) will not require new cicruiting. I like to use 13A as a max but that is a design item, code says 16A.
Re: 277 VOLT LIGHTING
If it is a bid job, or a not to exceed price, you can't afford to plan for what may happen. Load the circuits to 80%, this lighting will be continuous load. Make a note of this on the "as built" prints. Anyone installing more lighting can run home.
[ December 31, 2003, 12:07 PM: Message edited by: bennie ]
If it is a bid job, or a not to exceed price, you can't afford to plan for what may happen. Load the circuits to 80%, this lighting will be continuous load. Make a note of this on the "as built" prints. Anyone installing more lighting can run home.
[ December 31, 2003, 12:07 PM: Message edited by: bennie ]
Re: 277 VOLT LIGHTING
Kiss,
You Are Probably Going To Be Able To Get Approximately (75) Two Lamp Light Fixtures On A 20A 277V Circuit.
2 Lamp Electronic Ballast With 2 32 Watt Lamps Will Draw Approximatley 59 Watts.
16A * 277V = 4432 Watts
4432 Watts / 59 Watts Per Fixture = 75.12 Light Fixtures (Round Down To The Nearest Whole Number 75 Light Fixtures)
-Ed
Kiss,
You Are Probably Going To Be Able To Get Approximately (75) Two Lamp Light Fixtures On A 20A 277V Circuit.
2 Lamp Electronic Ballast With 2 32 Watt Lamps Will Draw Approximatley 59 Watts.
16A * 277V = 4432 Watts
4432 Watts / 59 Watts Per Fixture = 75.12 Light Fixtures (Round Down To The Nearest Whole Number 75 Light Fixtures)
-Ed
Re: 277 VOLT LIGHTING
You should actually be using the rated input current of the ballast instead of the rated input wattage. Due to power factors and losses, the rated input current is the safest way to go.
If you have electronic ballasts with 20% or less THD, I think 80 watts per fixture would be a safe number to use. (I.E..the current for each ballast probably wouldn't be more than 80W/277V = about 0.29 amps).
Steve
You should actually be using the rated input current of the ballast instead of the rated input wattage. Due to power factors and losses, the rated input current is the safest way to go.
If you have electronic ballasts with 20% or less THD, I think 80 watts per fixture would be a safe number to use. (I.E..the current for each ballast probably wouldn't be more than 80W/277V = about 0.29 amps).
Steve
- Location
- Massachusetts
Re: 277 VOLT LIGHTING
You certainly can put a lot of fixtures on a 277 volt circuit.
Just a suggestion do not do this, one circuit trips or needs service and you put a whole lot of people out of lights. This can be a real hassle if you have to change ballasts when the space is occupied.
Or, load em up, but alternate 2 circuits by rows.
Row 1 circuit A, Row 2 circuit B and so on.
Just a suggestion, not a requirement.
You certainly can put a lot of fixtures on a 277 volt circuit.
Just a suggestion do not do this, one circuit trips or needs service and you put a whole lot of people out of lights. This can be a real hassle if you have to change ballasts when the space is occupied.
Or, load em up, but alternate 2 circuits by rows.
Row 1 circuit A, Row 2 circuit B and so on.
Just a suggestion, not a requirement.
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
Re: 277 VOLT LIGHTING
I think your right Steve as every ballast I have see has a multiplier to use when adding the ballast loss to the bulb wattage
I think your right Steve as every ballast I have see has a multiplier to use when adding the ballast loss to the bulb wattage
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