480V ballast for parking lot lights

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Davebones

Senior Member
Location
North Of Tampa Fl
Contractor changing our parking lot lights wants to use 277V instead of 480V .He says they are doing away with the 480V ballasts due to safety . Is that a true statement ???
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Guess it's his true opinion :)
As noted in 210.6, unless you are dealing with dwelling units, there is not a limitation on using 480 volt lighting as long as the SYSTEM is 480Y/277 (not the circuit) .
The "safety" issue is in the eye of the beholder.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
If the parking lot was designed for 480 volt fixtures, the wiring and breaker sizes most likely would be too small. Voltage drop is a big issue too, with long runs typical of parking lots, the new 277 volt ballast and lamps would fail quickly due to the undervoltage at the far ends of the parking lot. This is a very bad idea.
 
growler

growler

Senior Member
Location
Atlanta,GA
hillbilly1 said:
Yes, that would change the equation, I was assuming same wattage to same wattage.:)
Click to expand...

I'm just guessing that he is retrofitting the fixtures and has found a way to reduce wattage.

The OP said it's for safety reasons and that really doesn't make sense to me. So I was thinking that maybe he is useing safety as an excuse to sell a retrofit. Or an excuse to switch the circuits from 480V to 277V so he can use a particular brand of fixture.

480V is 277V to ground and 277V is 277V to ground so i don't see where it would be any safer.

The world is changing and I don't have the slightest idea what's going on most of the time so maybe someone, somewhere did decide the 480V was dangerous for some reason. There sure would be a lot of balast to change out. :D
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
jeremysterling said:
277V means socket screw shell is 0 volts to ground.

480V means socket screw shell is ~277 volts to ground. Some countries (like Canada) do not allow this because of safety concerns.
Click to expand...

True, Canadians do not allow the screw shell to be "hot", but since it has equal insulation to ground as the center terminal the only way it would be dangerous is if you are trying to remove or install the lamp live which would expose the screw shell of the lamp until it is seated, but again you shouldn't be installing the lamp live anyway.:grin:
 
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Kdog76

Senior Member
Location
The Dairyland State
I recently was on a job where we swapped out a bunch of ballasts on parking lot light poles that had 480 and we went to a 208 system. Only because the old 480 feed was underground fed from a different building. We swapped out the ballasts because they only had 480/110 volt taps (no 208 taps). SO, we got all new ballasts with the 208 taps.
The fixtures were 400 watt metal halide. Well, we did not expect that we needed pulse start bulbs. SO then we went back up and replaced all the bulbs too. Kinda a big headache. But we got it.
On any of the ones that I've ever seen I don't think a 480 volt system is more or less any safe then any other voltage for lighting, if installed and serviced properly.
 
growler

growler

Senior Member
Location
Atlanta,GA
jeremysterling said:
277V means socket screw shell is 0 volts to ground.

480V means socket screw shell is ~277 volts to ground. Some countries (like Canada) do not allow this because of safety concerns.
Click to expand...


So the screw shell is always going to have 0 volts to ground? All you need is one idiot to reverse polarity and right back to 277v to ground on the screw shell.

If anyone thinks they can go around touching the screw shell on even 120V fixtures then sooner or later they will get an unpleasant surprise.

Some countries (like canada) may think they are being safer but I still don't see it. These are not fixures that are going to be maintained by homeowners, these are comemrcial fixtures and the people working on them should know what they are doing. There is no way I'm ever going to trust a screw shell to have 0 volts to ground.

Hillbilly1 got it right right. Who changes these lamps out hot anyway?
 
Cavie

Cavie

Senior Member
Location
SW Florida
jeremysterling said:
277V means socket screw shell is 0 volts to ground.

480V means socket screw shell is ~277 volts to ground. Some countries (like Canada) do not allow this because of safety concerns.
Click to expand...

American Highway Street lighting 480 volts is Socket Screw Shell 0 volts to ground. 480 volt 2 wire, one hot, one neutral.
 
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Bigrig

Member
Location
Dayton, OH
I have specified 480V site lighting on at least 30 projects in the last 2 years and no inspector has ever mentioned it as a safety concern. Have the contractor produce load and voltage drop calculations showing that it will work with the existing wiring layout. I suspect either he has a lot of 277 ballasts left over from another project or he wants to sell additional work including replacing the conductors/adding circuits.
 
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