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Thread: main switch on industrial control panels for use in hazardous locations

  1. #1
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    main switch on industrial control panels for use in hazardous locations

    Dear all,
    greetings from Germany and a short question

    I have to adapt a cabinet which is UL508A to a location Class I Division 1.
    It will be x-purged.
    Actual I have a main switch (20A) in the door which internally switches a circuit breaker (UL489).

    For Class I Division 1 I need to switch off the cabinet in case of pressure loss.
    I believe I would need a contactor in an Ex d box. So this switches power to the cabinet or off.

    Do I need almost the switch in the door? Cabinet can only be opened with a tool.

    And is it allowed to wire power lines first to the contactor in the Ex d enclosure and then to the circuit breaker in the pressurized cabinet?
    I am thinking about the SCCR rating.

    Click image for larger version. 

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    Beforehand may thanks for your support/comments

  2. #2
    Join Date
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    IMO, your best bet is to just buy a listed type X purge/pressurization system rather than trying to make your own.

    here is just one example.

    https://www.pepperl-fuchs.com/usa/en/classid_1783.htm

    The SCCR of whatever feeds the control panel will need to accommodate whatever the available short circuit current is at the terminals of the feeding device.

    It might well be more cost effective depending on just what you have to put it in an XP enclosure. However, if you are trying to list it to UL508s, you won't be able to do that.
    Bob

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