So GC has a job changing 277v. high bay lights to fluorescent, in a warehouse. First guy was doing fine until, he ran into some lights that he thought were 277v. wired, but were 480v. wired. He hooked up the new lights and boom. He said whoever hung them didn't identify that the white was being used as a hot. I don't know. I'm thinking, you see that the white wire is not landing on another white or gray wire? Right? So a lot of ballast need to be changed, and light bulbs.:jawdrop: Did this guy screw up, or was it a honest mistake? Have you heard of anyone doing this before? I guess there's a lesson learned here. Check it no matter what color it is!
hooking up 277v. lights to a 480v. circuit
- Thread starter zappy
- Start date
- Status
- Occupation
- Licensed Electrician
I'm saying the guy screwed up. Never assume color means anything.
How old is the original installation? At one time a grey wire could be either grounded or hot.
How old is the original installation? At one time a grey wire could be either grounded or hot.
Wow never knew that.
- Location
- Illinois
- Occupation
- retired electrician
There has been a note in the code to that effect since they changed the term "natural gray" to just gray.
ksmith846
Senior Member
- Location
- Port St Lucie, Florida
Circuit Breaker?
Circuit Breaker?
I wonder how the person did not know that the circuit was 480V. I would have been turning off the circuit breakers which fed those light fixtures. In doing so I think I would have noticed that I was turning off a 2 pole breaker.
I am guessing that the original fixtures were cord and plug connected maybe and he did not have to turn off any breakers...???
Circuit Breaker?
I wonder how the person did not know that the circuit was 480V. I would have been turning off the circuit breakers which fed those light fixtures. In doing so I think I would have noticed that I was turning off a 2 pole breaker.
I am guessing that the original fixtures were cord and plug connected maybe and he did not have to turn off any breakers...???
kwired
Electron manager
- Location
- NE Nebraska
2 or 3 pole breaker could be feeding MWBC and still have 277 volt loads connected to it.
Many times all the ballast leads especially on magnetic ballasts are all white. The voltage taps typically have the voltage imprinted in the insulation. Blaming the previous installer does not change the fact that the new ones are destroyed. This is a lesson on paying attention to what is existing when doing something like this, you never know what may have been done that is not obvious.
- Location
- Simi Valley, CA
While he might have made a mistake, I'm going to say that it was an honest mistake. If I was working in a building or an area and had run into all 277v lighting, I would probably "assume" that all of the lighting was 277v.
Now as a former facilities electrician, I know that's not always the case.
Now as a former facilities electrician, I know that's not always the case.
So the warehouse next door were 277v. fixtures everywhere. So when he went to the next warehouse, he just assumed they were 277v. But they weren't. All of them were 480v. Everything was cord&plug. So he would take down the old fixture and put a cord&plug on the new Flo. fixtures and plug them in.
There were signs everywhere, if he was paying attention. The 480v. fixtures said 480v. right on the ballest, and on the wire insulation. The first warehouse the breakers were single pole, the next one was all two pole breakers.
So I guess when he was taking off the old cord&plug on the fixture and putting it on the new Flo. fixture, and when it just plugged right in, OK cool. And kept going. I don't know if I would have done the same thing. Kinda tough. But I will learn from his mistake!
Also something weird, some of the 277.v Flo. fixtures would burn out right away, and some nothing happened yet, and some two bulbs would be out.
Question. Are the 277.v outlets, and the 480v. outlets the same? Or would you need 277v. outlets and plugs, and also need 480v. outlets and plugs? I imagine one outlets says B, W, G and one says B, R, G? And would a 277v. plug, plug into a 480v. receptacle or vice versa?
There were signs everywhere, if he was paying attention. The 480v. fixtures said 480v. right on the ballest, and on the wire insulation. The first warehouse the breakers were single pole, the next one was all two pole breakers.
So I guess when he was taking off the old cord&plug on the fixture and putting it on the new Flo. fixture, and when it just plugged right in, OK cool. And kept going. I don't know if I would have done the same thing. Kinda tough. But I will learn from his mistake!
Also something weird, some of the 277.v Flo. fixtures would burn out right away, and some nothing happened yet, and some two bulbs would be out.
Question. Are the 277.v outlets, and the 480v. outlets the same? Or would you need 277v. outlets and plugs, and also need 480v. outlets and plugs? I imagine one outlets says B, W, G and one says B, R, G? And would a 277v. plug, plug into a 480v. receptacle or vice versa?
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