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Thread: Old conventions

  1. #11
    Join Date
    Jul 2011
    Location
    VA
    Posts
    47
    The company I did my apprenticeship with had a 3/4" min. rule. Just made it easier to stock jobs. Less sizes to keep up with and more room to pull wire. Worked for them....they were pretty "old school".
    "My goal is to not screw up so bad that they name the screw up after me!"

  2. #12
    Join Date
    Dec 2016
    Location
    Waco, tx
    Posts
    48
    I think the 3/4” minimum is the way to go. I recommend you to go and try to push a fish tape and pull wire through 1/2” RMC. It is near impossible if you have multiple bends(I.e. a pipe run down a conveyer.)

    #12 is fine for power circuits, but it can be an issue to terminate in some devices for control circuits. This is just my opinion from field experience.


    Sent from my iPhone using Tapatalk

  3. #13
    Join Date
    Apr 2009
    Location
    Williamsburg, VA
    Posts
    5,438
    When I was doing voice / data / video, we would run three quarter inch everywhere, even with a riser set up from the 3rd to 4th floor, and the first floor boxes. It was cheaper overall to spec all three quarter inch conduit and fittings rather than have 500 foot of half inch Smurf pipe or 5 dozen half inch fittings left over.

    Three-quarter inch conduit also has roughly twice the fill limit of half inch.
    Electricians do it until it Hertz!

  4. #14
    Join Date
    Jan 2007
    Posts
    3,552
    Quote Originally Posted by minerman View Post
    Hello!

    I work for a company who does industrial installations, sometimes outdoors.

    We use a lot of rigid metal conduit and thhn/thhw wire.

    My boss for the longest time would refuse to use smaller wire or conduit for 480V wiring. As a rule of thumb, he would never allow us to spec. anything smaller than #12 wire for 480V power wiring and never anything under #14 for 120V or DC wiring. He also would never allow us to use anything smaller than 3/4" rigid metal conduit.

    When we asked him why, we never got a good reason. It was always, "This is how we've always done it, it's not going to change!"

    Well, he has left the company and now I'm the decision maker. Do these old conventions have any reasoning behind them? I would like to be able to use #14 thhn/thhw wire for 480V power feeds and 1/2" conduit where allowed.

    Does anyone know where these conventions originated from?

    Thanks!
    You're right.

    There's absolutely nothing wrong with using #14 wire and 1/2" conduit for 480v circuits.

    Sounds like your old boss was old school.

    With that being said,,,,, I completely agree with your old boss's way of doing things and wouldn't change a thing.

    Most times, experience out weighs anything you'll ever see drawn on paper.

    JAP>

  5. #15
    Join Date
    Jan 2007
    Posts
    3,552
    Quote Originally Posted by minerman View Post
    Thanks for the commentary. I'm glad you all seem to agree. LOL at the ham story.

    I do agree,,,, with your old boss's way of doing things that is.


    JAP>

  6. #16
    Join Date
    Feb 2003
    Location
    Seattle, WA
    Posts
    19,034
    Did anyone notice that this thread is four years old? Let's not add anything more to it. If you have something you wish to say, please start a new thread.
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

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