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Thread: 480V circuit in EMT

  1. #1
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    480V circuit in EMT

    I've been informed that a coworker of mine overheard someone say that you can't put 480V circuits in EMT conduit. I couldn't find any justification for this comment in Article 358 Electrical Metallic Tubing. Can someone please clarify?

  2. #2
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    It's false.

    He might be talking about a job spec, but if so, it's a very unreasonable one.

  3. #3
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    You can put 480 in MC cable so why would EMT be prohibited?
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

  4. #4
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    Quote Originally Posted by Malteser View Post
    I've been informed that a coworker of mine overheard someone say that you can't put 480V circuits in EMT conduit. .........
    If that's true, I've installed miles of Code violations. I suspect you'll find it on page 37 of the Urban Legend Electrical Code.

  5. #5
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    NM cable is rated for 600 volts. You may very rarely see it used on 277/480 volts, but it can be used as long as there is no restriction on NM for other reasons.

  6. #6
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    I see that on a lot of industrial project specs, especially Water / Wastewater plants. But it's not a code thing, it's an engineer's preference thing.
    __________________________________________________ ____________________________
    Many people are shocked when they discover I am not a good electrician...

  7. #7
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    Quote Originally Posted by kwired View Post
    NM cable is rated for 600 volts. You may very rarely see it used on 277/480 volts, but it can be used as long as there is no restriction on NM for other reasons.
    We used to run a lot of 480 & 277 in NM. That pretty much stopped when the NEC restricted NM above dropped ceilings.

    Don't snip that 12/3 going by thinking 'no big deal its 120 volt travelers', its really a 3 phase 480 circuit to a fan. POW!

  8. #8
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    Quote Originally Posted by 480sparky View Post
    If that's true, I've installed miles of Code violations. I suspect you'll find it on page 37 of the Urban Legend Electrical Code.
    I'd like to see Mike Holt publish that book, explaining common NEC myths, how they came to be, and what the reality is on that subject matter.

  9. #9
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    Quote Originally Posted by iwire View Post
    We used to run a lot of 480 & 277 in NM. That pretty much stopped when the NEC restricted NM above dropped ceilings.

    Don't snip that 12/3 going by thinking 'no big deal its 120 volt travelers', its really a 3 phase 480 circuit to a fan. POW!
    And 90% of the electricians hearing this died from heart attacks just pondering 480 volts on NM cable.

  10. #10
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    Quote Originally Posted by iwire View Post
    We used to run a lot of 480 & 277 in NM. That pretty much stopped when the NEC restricted NM above dropped ceilings.

    Don't snip that 12/3 going by thinking 'no big deal its 120 volt travelers', its really a 3 phase 480 circuit to a fan. POW!
    More like KAAAABOOOOMMMM>.....


    JAP>

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