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Thread: Overdutied Equipment Labeling

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  1. #1
    Join Date
    Mar 2013
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    Rutland, VT, USA
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    Overdutied Equipment Labeling

    Is there any code requirement to label equipment that is found to be overdutied as a result of an electrical systems study? i have looked but have not found anything on required labeling. How do workers in the field know equipment is overdutied?

    Granted it needs to be replaced but that does not always happen rapidly so there is a period of time where the equipment is known to be overdutied but still in service.

  2. #2
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    San Francisco Bay Area, CA, USA
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    From an AHJ's standpoint, the labeling would be a red tag ceasing operation. There is nothing in the NEC addressing your situation, because the situation violates the NEC rules from the outset. 110.3; suitable for the intended use.

    One might go so far as to say this is one main REASON why the NEC exists in the first place!
    __________________________________________________ ____________________________
    Many people are shocked when they discover I am not a good electrician...

  3. #3
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    Dec 2007
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    What exactly do you mean by "overdutied".

    I can show you several applications where if you counted every possible connected load a larger supply would be needed, but if you recorded demand data the maximum load ever seen is still less then the supply rating.

    1200 amp service but utility only installs a transformer with secondary current rating of ~600 amps - they know what the real load is and won't put in a larger transformer unless there is load there to justify it.

    Now if that 1200 amp service actually has more then 1200 amps of load - you are going to have overcurrent protection trips reminding people there is a problem, but the equipment is essentially protecting itself.

  4. #4
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    Quote Originally Posted by kwired View Post
    What exactly do you mean by "overdutied".
    I have only seen that term used where the available fault current is greater than the equipment rating.
    The more they overthink the plumbing, the easier it is to stop up the drain

  5. #5
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    depends entirely on what you mean by "overdutied".
    Bob

  6. #6
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    Quote Originally Posted by dkidd View Post
    I have only seen that term used where the available fault current is greater than the equipment rating.
    Never gave that aspect any thought but I guess it could be what OP is asking about.

  7. #7
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    Mar 2013
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    Yes, the term is commonly used to indicate equipment that is not rated for the available fault current. Examples:

    Circuit breaker with a 18kA AIC rating but the available fault current is 23kA

    Panel rated 10kA but available fault current is 12kA

    Both of these would be considered overdutied and not only an NEC violation but an OSHA violation also.

    Note this has nothing to do with loading only short circuit.

  8. #8
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    Jun 2017
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    It happens. There should be reasonable evaluation as to why the existing equipment ratings as less than true available. Generally, utility agreements maintain a threshold of allowable increase in available fault current. That would be my first investigation.

    Otherwise, one might take measures to solve this short/long term by having an engineered series rating modifications.

    Otherwise, yes - there is cause for concern. However, it depends on the situation. If this equipment were in an unoccupied vault, for instance, maybe it is reasonable to continue operation for while waiting on lead time needed for replacement. Maybe the same is true for an occupied space, so long as NFPA 70E alerting techniques are followed to avoid technicians operating the equipment. Maybe you’d consider different if it were an industrial facility under single management.

    We have all seen equipment with high enough AIC ratings needed, but the equipment condition itself is questionable - that same equipment continues to be in operation for many years beyond service life should be subject to the same criticisms, but they aren’t always.

    Some due diligence is needed when we find these and the specific solution...depends. In all cases, owners carry high liability and OSHA is waiting in the shadows.

  9. #9
    Join Date
    Dec 2010
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    There is a good discussion of the topic with sample labels here https://brainfiller.com/arcflashforu...hp?f=24&t=4518
    The more they overthink the plumbing, the easier it is to stop up the drain

  10. #10
    Join Date
    Feb 2013
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    India
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    Why not also send a note to OSHA as a responsible electrical professional?

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