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Thread: Running 460VAC, 3-phase together with 24VAC, 1-phase power?

  1. #1
    Join Date
    Oct 2017
    Location
    Wisconsin
    Posts
    17

    Running 460VAC, 3-phase together with 24VAC, 1-phase power?

    Hello everyone!

    I have 460VAC, 3-phase power cables each run with 600V rated power cable.
    I have 24VAC control power each run with 600V rated power cable. Each control power cable is a dry-contact (a high-level switch) run to a computer supplying 24VAC wetting voltage.

    I would like to run the 460VAC & the 24VAC cables next to each other.

    The cables will be run against a sheet-metal box and fastened with zip-ties to a listed support. So the cables will not be run in raceway or cable tray.

    My question:
    Is there any PRACTICAL reason or any NEC code-specific reason why I should NOT run this 460VAC, 3-phase power next to this 24VAC control power?
    Last edited by rustydud; 11-14-17 at 12:16 PM.

  2. #2
    Join Date
    Oct 2017
    Location
    Wisconsin
    Posts
    17
    Any thoughts?
    Can I provide any additional information?
    Thanks.

    Quote Originally Posted by rustydud View Post
    Hello everyone!

    I have 460VAC, 3-phase power cables each run with 600V rated power cable.
    I have 24VAC control power each run with 600V rated power cable. Each control power cable is a dry-contact (a high-level switch) run to a computer supplying 24VAC wetting voltage.

    I would like to run the 460VAC & the 24VAC cables next to each other.

    The cables will be run against a sheet-metal box and fastened with zip-ties to a listed support. So the cables will not be run in raceway or cable tray.

    My question:
    Is there any PRACTICAL reason or any NEC code-specific reason why I should NOT run this 460VAC, 3-phase power next to this 24VAC control power?

  3. #3
    Join Date
    Jul 2005
    Location
    Tennessee
    Posts
    15,416
    My first thoughts revolve around "The cables will be run against a sheet-metal box and fastened with zip-ties to a listed support". I have a problem seeing where that meets NEC under Art 400 or Art 336.
    Beyond that I would take a look at Art 725.136 to make sure there is not a violation.
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  4. #4
    Join Date
    Jun 2003
    Location
    NE (9.1 miles @5.07 Degrees from Winged Horses)
    Posts
    8,859
    Typical would be 18” of separation IIRC. Depending on the motor load and your control characteristics, it could give you some grief.
    Tom
    TBLO

  5. #5
    Join Date
    Jun 2003
    Location
    Hawthorne, New York NEC: 2014
    Posts
    3,163
    As long as one or the other is a listed cable (and you have both) there is no prohibition in the NEC for running them together. From a design standpoint, as something that may possibly cause operational problems I can't comment.

    -Hal

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