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Thread: 24VDC Power Supply in a Class I Div II Area

  1. #1
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    24VDC Power Supply in a Class I Div II Area

    Hey folks I appreciate any help in advance.
    I am tasked with putting a 24VDC 100W power supply in Div II location to supply power to a couple of strobes and a horn. Previously this "Alarm Station" was built using a Div I explosion proof enclosure which is heavy with less space inside for the Din Rail, Power Supply and Terminal Blocks.
    So, I have been researching and getting quite confused by all of the NEC requirements. Can I use a Div. II enclosure and fittings for the AC input and DC output along with a Div II power supply, or possibly even a non-rated power supply if the enclosure is also Nema 4X or is the big cast aluminum Div I XP enclosure necessary?
    Thanks again in advance for the help and any other advice and recommendations regarding the best ways to do this are very welcome.

  2. #2
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    the easiest solution is to buy a power supply that is already rated for C1D2.

    many are available. here is just one.

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    Bob

  3. #3
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    Quote Originally Posted by petersonra View Post
    the easiest solution is to buy a power supply that is already rated for C1D2.

    many are available. here is just one.

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    If I use a C1D2 power supply can I put it in a Weatherproof box and meet the requirements or is a Div2 enclosure still required since I will likely need Div2 connectors or cable glands?

  4. #4
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    Quote Originally Posted by Aubrey M View Post
    If I use a C1D2 power supply can I put it in a Weatherproof box and meet the requirements or is a Div2 enclosure still required since I will likely need Div2 connectors or cable glands?
    There is no such thing as a "div 2" enclosure.

    take a look at 500.7 (G).

    If the equipment is listed as non-incendive it can be used in a C1D2 area. You need go no farther.

    The enclosure type rating should be based on the environment the enclosure is located in.

    Read the instructions the NI equipment comes with and follow them.
    Bob

  5. #5
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    Quote Originally Posted by Aubrey M View Post
    If I use a C1D2 power supply can I put it in a Weatherproof box and meet the requirements or is a Div2 enclosure still required since I will likely need Div2 connectors or cable glands?



    Enclosures are either 'required to be explosion proof' or they're not. If the power supply is rated for CID2 environment, there would be no need to use an explosion proof enclosure, such as Nema 7 with threaded hubs. You could use a sheet metal enclosure such as Nema 4X (you wouldn't need to seal) but you'd still need to bond to the enclosure per 501.30.

  6. #6
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    Quote Originally Posted by Dale001289 View Post
    Enclosures are either 'required to be explosion proof' or they're not. If the power supply is rated for CID2 environment, there would be no need to use an explosion proof enclosure, such as Nema 7 with threaded hubs. You could use a sheet metal enclosure such as Nema 4X (you wouldn't need to seal) but you'd still need to bond to the enclosure per 501.30.

    Thanks again for all of the help and clarification. Now for a really dumb question....is there a place I can download the NEC? I searched and ended up at the NFPA website and got lost soon thereafter.

  7. #7
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    Quote Originally Posted by Aubrey M View Post
    Thanks again for all of the help and clarification. Now for a really dumb question....is there a place I can download the NEC? I searched and ended up at the NFPA website and got lost soon thereafter.
    This is the page you want.

    You can also get an Apple or Android app.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

  8. #8
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    Quote Originally Posted by rbalex View Post
    This is the page you want.

    You can also get an Apple or Android app.
    Buy the PDF version. It is much easier to find things via electronic search.
    Bob

  9. #9
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    Your company should purchase it for you if it's required for your work.

  10. #10
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    Quote Originally Posted by MRKN View Post
    Your company should purchase it for you if it's required for your work.

    Back in the 'good ol days' companies used to spring for Code books... OR you could purchase them dirt cheap locally, usually at distributors like Greybar.
    Times have changed.

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