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Old 08-26-2013, 08:33 AM   #1
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277 v fixture question


Why does a 277 v fixture only uses one hot wire ,neutral and ground shouldn't it use two hots instead?:/

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Old 08-26-2013, 08:37 AM   #2
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277 v fixture question


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Originally Posted by RAUL HIDALGO
Why does a 277 v fixture only uses one hot wire ,neutral and ground shouldn't it use two hots instead?:/
The white wire should be marked black to indicate its a hot wire too. What kind of fixture are you using

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Old 08-26-2013, 08:42 AM   #3
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277 v fixture question


This is the fixture in question. I understand that the white should be black but when I touched the white wire there was no power on it( that's to say I didn't got schocked)

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Old 08-26-2013, 08:45 AM   #4
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277 v fixture question


277 volts is part of a 3 phase 480 wye configuration whereas, each phase to neutral/ground is 277 volts.

So there isn't "2 hots".
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Old 08-26-2013, 08:48 AM   #5
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277 volts is part of a 3 phase 480 wye configuration whereas, each phase to neutral/ground is 277 volts.

So there isn't "2 hots".
Finally I get it now ,thank you very much sir, now that I think about it there are some transformers inside the building ,it all fits now
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Old 08-26-2013, 09:16 AM   #6
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277 v fixture question


Sorry, for what ever reason I was thinking 240 volt with two hots. I forgot about the three phase 480
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Old 08-26-2013, 09:42 AM   #7
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277 v fixture question


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Sorry, for what ever reason I was thinking 240 volt with two hots. I forgot about the three phase 480
"Forgetting" is a poor excuse for giving out information that is both wrong and dangerous
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Old 08-26-2013, 01:38 PM   #8
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277 v fixture question


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The white wire should be marked black to indicate its a hot wire too. What kind of fixture are you using
It's because the hot wire is 277V if you had 2 hots that would make it 480V. it has to do with the transformer suppling the building in residential the transformers only supply 120/240 in commercial with different trans formers they are 277/480 a Y transformer 3phase each leg carries 277V. it get a little complicated to explain
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Old 08-26-2013, 02:00 PM   #9
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277 v fixture question


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Originally Posted by 1cashking View Post
277/480 a Y transformer 3phase each leg carries 277V. it get a little complicated to explain
480/1.732 (square root of 3) is 277.

Piece-o-cake
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Old 08-26-2013, 02:13 PM   #10
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277 v fixture question


I'll just stick with residential wiring

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Old 08-27-2013, 01:49 AM   #11
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277 v fixture question


yes it could be complicated 120/240 is from a 3phase delta transformer with no stinger if it had a stinger leg 120X1.5=180V it would be tapped from between 2 hots to ground at the transformer used mainly for industrial heavy motor loads. this takes me back to my school days. Thanks for making my brain work again!
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Old 08-27-2013, 04:14 PM   #12
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277 v fixture question


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Why does a 277 v fixture only uses one hot wire ,neutral and ground shouldn't it use two hots instead?:/
Are you working on 277V lights in a commercial or industrial setting? If so that is not DIY work.
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Old 08-27-2013, 07:19 PM   #13
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Are you working on 277V lights in a commercial or industrial setting? If so that is not DIY work.
Don't worry , yes I was installing the fixtures but under the supervision of a master electrician and the question just came to mind, however not everyone is so willing to answer like you guys.
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Old 08-27-2013, 07:29 PM   #14
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Don't worry , yes I was installing the fixtures but under the supervision of a master electrician and the question just came to mind, however not everyone is so willing to answer like you guys.
277 is a nasty voltage to work with. Mostly because people seem to want to treat is like 120 volt. Not realizing that 277 doesn't like to give people a second chance.

I've seen guys get lucky with it though. One guy, it went in his elbow, and blew a hole in his middle finger where it was touching a neutral. No blood though. it was 2 weeks before it started to bleed.

So please, be careful.
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Old 08-27-2013, 07:40 PM   #15
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277 is a nasty voltage to work with. Mostly because people seem to want to treat is like 120 volt. Not realizing that 277 doesn't like to give people a second chance.

I've seen guys get lucky with it though. One guy, it went in his elbow, and blew a hole in his middle finger where it was touching a neutral. No blood though. it was 2 weeks before it started to bleed.

So please, be careful.
I always treat every installation like its energized even if I'm asured its not, however in these case it was live so I was extra careful( if such a thing exists ) thanks though.

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