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Thread: Motors in Hazardous Locations

  1. #11
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    Mar 2013
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    This is something that has confused me. Who is ultimately responsible for making the determination on the suitability of equipment for a hazardous location? Is it the AHJ, which I know varies from town to town...and in some instances is an NRTL? Is the best approach to use the NEC and relevant ANSI standards and have them as a defense/explanation of your design choices to present to the final AHJ?
    Time is of the essence, and I am low on essence. ~ Graham Hill

  2. #12
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    Quote Originally Posted by fifty60 View Post
    This is something that has confused me. Who is ultimately responsible for making the determination on the suitability of equipment for a hazardous location? Is it the AHJ, which I know varies from town to town...and in some instances is an NRTL? Is the best approach to use the NEC and relevant ANSI standards and have them as a defense/explanation of your design choices to present to the final AHJ?
    In general:

    The AHJ is responsible for determining the acceptability of anything you use. However, keep in mind the AHJ is not the same thing as the inspector.

    Most AHJ will accept an NRTL listing as meaning the equipment is acceptable for a particular use. Some AHJs have rules requiring that a listed product be considered acceptable for a use within the listing.

    Identified (as applied to equipment). Recognizable as
    suitable for the specific purpose, function, use, environment,
    application, and so forth, where described in a particular
    Code requirement.
    Is a different concept than listed as it does not have to involve an NRTL, although it could and often does. If an NRTL is not involved, most times it is the manufacturer of the product that would so identify something as being suitable. An AHJ is not required to accept the manufacturer's judgement of suitability but most do.

    I am not entirely sure what you are proposing to do. If you want to evaluate a motor made by someone else on your own, I think you are going to have a tough time getting an AHJ to accept that evaluation. If you want to use the motor manufacturer's evaluation, chances are pretty good most AHj would accept it without much in the way of comment.
    Bob

  3. #13
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    Apr 2004
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    Quote Originally Posted by fifty60 View Post
    This is something that has confused me. Who is ultimately responsible for making the determination on the suitability of equipment for a hazardous location? Is it the AHJ, which I know varies from town to town...and in some instances is an NRTL? Is the best approach to use the NEC and relevant ANSI standards and have them as a defense/explanation of your design choices to present to the final AHJ?
    First, thanks Bob (petersonra) – good response.

    Second, fifty60, as an exercise left to the student, (you will remember it better) I’m going to suggest you start with NEC Section 110.2 and follow the chain of definitions (Article 100) and Informational Notes (IN) that arise. Ultimately, the chain will lead to the definition of Authority Having Jurisdiction and its rather long and moderately convoluted Informational Note.

    110.2 Approval. The conductors and equipment required or
    permitted by this Code shall be acceptable only if approved.

    Informational Note: See 90.7, Examination of Equipment
    for Safety, and 110.3, Examination, Identification, Installation,
    and Use of Equipment. See definitions of Approved,
    Identified, Labeled, and Listed.

    [RBA Note: Identified’'s IN may be misleading – read it carefully]
    For an even better exercise, see FedOSHA’s definitions of Accepted, Acceptable, and Approved with respect to electrical installations. Eventually it will lead to who the AHJ actually is with respect to FedOSHA.

    The NEC definitions/INs will lead you to the fact that there may be many AHJs in any particular case – and they all have to be satisfied. FedOSHA’s definitions are often copied in some form by most StateOSHAs.

    I’ve been teaching young engineers (even a few PEs) nearly 50 years that you must first be an accountant and then a lawyer before you can actually do any engineering.
    "Bob"
    Robert B. Alexander, P.E.
    Answers based on 2014 NEC unless otherwise noted.

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