480V Circuit Tapped for 277V Lights

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HyVOLtage

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I have a new lighting installation using 480V metal halide fixtures, and was planning to use emergency/exit lights at all the exit doors. These fixtures are 277V. Instead of running a separate 277V circuit to these fixtures, is it NEC compliant to tap one of the "hots" from the 480V fixtures, and pull just the neutral from the panel? All of the lights will be fed from the same 480/277V panel. The only problem I see comes from having a 2-pole breaker sized to protect the 480V load, but using one of the poles to protect the extra 277V load.
 
Yes, they are left on 24/7 and if they were not, the circuits feeding the 277V emergency/exit lights would be "locked" on at the panel.
 
In this case, the exception in 700.12(F) would apply because there are three or more normal lighting circuits in the area.
 
HyVOL, make sure the neutral follows the pathway of the line conductor it complements, other than 2-wire switch loops.
 
HyVOLtage said:
I have a new lighting installation using 480V metal halide fixtures, and was planning to use emergency/exit lights at all the exit doors. These fixtures are 277V. Instead of running a separate 277V circuit to these fixtures, is it NEC compliant to tap one of the "hots" from the 480V fixtures, and pull just the neutral from the panel? All of the lights will be fed from the same 480/277V panel. The only problem I see comes from having a 2-pole breaker sized to protect the 480V load, but using one of the poles to protect the extra 277V load.
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Single pole with dedicated neutral.

I would use 3 pole CB's for the main lighting with balanced load on each phase. Saves some copper.
 
Thank you all. I think the conclusion I've come to is it is within the code to do what I stated, but it is probably not the best design, unless this was a remodel job, and I was out of circuits in the panel. I'm only talking about a couple of fixtures throughout the facility and each fixture is such a small load itself, that the total load difference on the 1-phase would be minimal.
 
I would also use the 3-pole breakers, but this is an existing facility that is adding on a process bay, and they want the main lighting to follow the existing layout. The engineering firm before used 2-pole breakers, so I am to follow them down that "hole". My whole thought was how to avoid having to run an extra circuit just to pick up a couple of emergency/exit lights that are 277V?
 
Not to steal your thread but i have a similar situation. we have lights on the corner of our warehouse and they are 277V lights. i knew that one leg of 480 to ground was 277 so i was going to just run one leg up to the light and i assumed it would work. We have 2 lights to power so i was going to use a spare bucket in our mcc and run 2 of the 480 legs to each light. run control wire for it and then voila, turn the lights on via the plc.

Will this work?
 
I don't know but what if you try this way run the transformer downstepped to 277v or even 120v by using a small single phase tranformer the primary side wired on 480 then secondary either 277 or 120volts.
you really dont need a big transformer if you going just powered a exit luminaire something like 300VA will do it otherwise run a seperated circuit for it.

Merci, Marc
 
Kurt, I wouldn't do it that way, for simplicity's sake. Somebody someday will curse whoever put that in. :)

Keep it simple, stupid. ;)


Besides, they take the machine offline for maintenance, replacement or repair and they lose the lighting.

Not having seen the place in the flesh, I'd say you should install a single pole switch on another circuit and call it good.
 
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