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Thread: UL 508A, yellow or orange wires in control panel from another power source

  1. #1
    Join Date
    Jan 2018
    Bradenton Florida

    UL 508A, yellow or orange wires in control panel from another power source

    I have a question on UL508A section 66.9.1 d). Which states that yellow or orange wire shall be installed in a control panel from another power source. Is it OK to pull red wire into the control panel from another source if it only terminates on a terminal strip then the internal wiring is then yellow or orange or does this violate the UL rating of the control panel?

  2. #2
    Join Date
    Jul 2006
    San Francisco Bay Area, CA, USA
    UL is not concerned with field wiring, that is governed by the NEC, which does not dictate control circuit wire colors.

    That said, if I were about to pull wires to a control panel and some of them were coming from an external source, I would follow that color scheme to help avoid confusion in the panel. The color coding is intended to give an electrician opening the panel an immediate way to identify circuits that may be live even if the panel disconnect is opened. The live red wires coming in from outside might be confused with the other red wires that are going to be dead.

    If your red control wires are already pulled, consider using yellow tape on them to help identify them as foreign. Think in terms of safety for the next brother electrician who opens that box with the boss breathing down his neck about getting back on line. It’s not always about what’s legal or not, sometimes it’s about professional courtesy.
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  3. #3
    Join Date
    May 2017
    SF Bay Area
    In your scenario the only way to identify that red wire as foreign voltage is by the yellow or red wire opposite on the terminal block. What if someone at a later date eliminates that circuit, removing that yellow wire? Then there is no way of knowing the red wire is foreign.

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