277V String Lights

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ntydrd

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Can I install 100A 277V incandescent lamps (e.g. Phillips 24661) in a temporary light stringer? If not, why are the lamps made? Alternatively, can I use 277V compact fluorescent lamps? The wire and sockets are 300V rated. It looks like NEC 210.6 (C) would forbid this. I am looking to use 277V for temporary lighting in hallways and 400W metal halide fixtures don't seem the best option for this application.
 

roger

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If your luminaires / lampholders meet the requirements of 210.6(C)

Roger
 

nakulak

Senior Member
I don't know if it is legal but to me it sounds like a very bad idea.

no matter where I have strung temporaries (high bays, etc), workers jack them around hard. I know a lot of drywall guys that wouldn't be around today if I had ever strung 277 temporaries. (I'm not trying to say it's a violation, but I agree with Bob)
 

dbuckley

Senior Member
I'm joining the throng of having 277V temp lights as a bad idea.

Same logic that you cant have 277V lights in a resi, and I'd opine that a resi is a less hazardous environment than a construction site.
 

Electric-Light

Senior Member
Same logic that you cant have 277V lights in a resi, and I'd opine that a resi is a less hazardous environment than a construction site.

While 277v is significantly more dangerously than domestic AC 240v, because the hot is floating 277v from ground while home system is only 120v, its not really that much worse than 415Y/240 derived 3phase commonly found in Europe.
 

iwire

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While 277v is significantly more dangerously than domestic AC 240v, because the hot is floating 277v from ground while home system is only 120v, its not really that much worse than 415Y/240 derived 3phase commonly found in Europe.

Actually the short circuit current will likely be much higher and there will be no GFP either.
 

dbuckley

Senior Member
While 277v is significantly more dangerously than domestic AC 240v, because the hot is floating 277v from ground while home system is only 120v, its not really that much worse than 415Y/240 derived 3phase commonly found in Europe.
In a domestic, commercial, or industrial situation that might be true, when you are running stringers, they run from whats popularly called a "building site transformer". It's 110V CT, so 55V to ground. And theres usually a RCD (a/k/a GFCI but with 30mA trip rather than 5mA) there as well for ground fault protection.

So I still say running stringers with 277 to ground is not what iI would call good practice.
 
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