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Thread: NEC articles addressing arc flash.

  1. #1
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    NEC articles addressing arc flash.

    I am working on a project in which I am specifying 480V and 4160V motor control centers. I want to make sure that I cover all my bases regarding arc flash. I have reviewed NFPA 70E, and am trying to locate all NEC articles that address arc flash. Below is a list of articles that I have already reviewed.

    110.16
    240.67
    240.87

    Do any other articles in NEC address arc flash mitigation requirements?

  2. #2
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    Not the NEC, but if you are embarking on this, I suggest getting hold of IEEE Std. 1584 — Guide for Performing Arc-Flash Hazard Calculations, and if possible, IEEE C37.20.7, the construction standards for MV Arc Resistant Equipment, because it provides you with definitions of terminology you will need to understand.
    __________________________________________________ ____________________________
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  3. #3
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    Quote Originally Posted by joshtrevino View Post
    I am working on a project in which I am specifying 480V and 4160V motor control centers. I want to make sure that I cover all my bases regarding arc flash. I have reviewed NFPA 70E, and am trying to locate all NEC articles that address arc flash. Below is a list of articles that I have already reviewed.

    110.16
    240.67
    240.87

    Do any other articles in NEC address arc flash mitigation requirements?
    I think you need to figure out what the IE is at the MCCs before you go any farther. That will tell you if you need to do any mitigating.
    Bob

  4. #4
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    Quote Originally Posted by joshtrevino View Post
    I am working on a project in which I am specifying 480V and 4160V motor control centers. I want to make sure that I cover all my bases regarding arc flash. I have reviewed NFPA 70E, and am trying to locate all NEC articles that address arc flash. Below is a list of articles that I have already reviewed.

    110.16
    240.67
    240.87

    Do any other articles in NEC address arc flash mitigation requirements?
    Looks like you have them. Are there specific concerns?

  5. #5
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    Beaumont, TX
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    No specific concerns. Upon issuing my scope of supply to the client, they were concerned that their specifications did not address arc flash requirements. I am in the process of explaining to them that most of the requirements are that a calculation must be done and the equipment must be properly labeled.

    I did add a maintenance switch to my data sheet for the main breaker relays to comply with 240.87.

    What is difficult is that they are having me hard bid the MCCs in FEL3 (front end engineering study) with multiple bidders/manufacturers. Therefore I am not certain the types of breakers and relays that will be used. My SKM model is incomplete for this reason. So I cannot do a proper arc flash analysis to determine IE. However, existing MCCs powered from the same switchgear the new will be powered from are not arc resistant.

    Publicgood, thanks for addressing the NEC concern.

    Jraef, I am familiar with IEEE 1584, but will consult
    C37.20.7
    if we find the need for arc resistant MCCs.

    Thanks all and any additional input is welcome. This board is always really helpful.

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