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Thread: 480v 120v signal same conduit?

  1. #1
    Join Date
    Feb 2009
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    Pennsylvania
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    480v 120v signal same conduit?

    Conduit with multiple conductors

    I have 480v 3-#3 for a hydraulic
    pump motor + ground

    3-#10 wires 2 for hydraulic oil heater one ground

    The above are in one conduit, I wanted to add 2-120volt control wires used to activate the oil heater. Thermostat in oil heater would activate #0 motor starter for heating element sending power on the #10 wires of course when motor would be running

    According to 725.48 this seems ok has anyone had problems by doing this. This was not first choice long story short some mistakes in design by vendor with devices selected

  2. #2
    Join Date
    Oct 2013
    Location
    newburgh,ny
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    422

    As long as wires are rated for highest voltage.

    As long as the wires are rated for the highest voltage and you are ok with conduit fill you can mix them. Since it only a relay I see no problem doing it that way, if you were talking mixing signal wires with 480 then only a maybe.
    A cowboy may get thrown , but they always get up and walk forward.

  3. #3
    Join Date
    Feb 2009
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    Pennsylvania
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    The 120v I guess is a signal wire used for the oil of a starter

  4. #4
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    Feb 2009
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    Pennsylvania
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    Coil of starter sorry

  5. #5
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    Dec 2007
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    NE Nebraska
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    Won't say I haven't possibly cheated on this a time or two but 725.48 (B)(1) says "Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated."

    Run a raceway to a 480 volt motor - it is fine to run a control circuit that is associated with that motor in the same raceway.

    Run a power circuit across a room and want to put a switch for some class 1 control circuit for a non associated motor in there because it is convenient and runs to the same area - not exactly in compliance with this section.

  6. #6
    Join Date
    Dec 2012
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    Placerville, CA, USA
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    Quote Originally Posted by kwired View Post
    Won't say I haven't possibly cheated on this a time or two but 725.48 (B)(1) says "Class 1 circuits and power-supply circuits shall be permitted to occupy the same cable, enclosure, or raceway only where the equipment powered is functionally associated."

    Run a raceway to a 480 volt motor - it is fine to run a control circuit that is associated with that motor in the same raceway.

    Run a power circuit across a room and want to put a switch for some class 1 control circuit for a non associated motor in there because it is convenient and runs to the same area - not exactly in compliance with this section.
    If the relay box is properly protected by a branch circuit OCPD, I don't see a problem with wiring the 120 as a power circuit that "powers" a relay. Then no restrictions.
    If you are making use of the "control" nature of the load to avoid some requirements for a more general power circuit, then you would be stuck.
    JMO

  7. #7
    Join Date
    Feb 2003
    Location
    Illinois
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    23,297
    This is a Class 1 control circuit, and the question is if the control conductors are functionally associated with both the oil pump and the oil heater.
    Don, Illinois
    Ego is the anesthesia that deadens the pain of stupidity. Dr. Rick Rigsby
    (All code citations are 2017 unless otherwise noted)

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