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Main Circuit Breaker Sizing

Discussion in 'Commercial Electrical Codes' started by mp25, Sep 27, 2018.

  1. mp25

    mp25 Registered User

    Jun 2, 2016
    Likes Received:
    Not an electrician, but am looking at some plans for a small restaurant with most cooking/reheating equipment being electrical. Code is 2017 NEC. Load calculations is below. the actual numbers don't matter as much as the total.

    Lighting for restaurants xxx sq. ft. x 2 va per sq. ft. @ 100%
    heating/cooling = higher of the two as they are non-coincidental @ 100%
    kitchen equipment xxx va @ 65% demand factor as there are more than 6 appliances
    receptacle load less than 5,000 va so at 100%
    continuous loads xxx va @ 125%

    after all that is added up, the number comes out to 190 AMPS. All the loads are pulled from a panel with a 200 AMP main breaker. Is this code compliant?

    I am being told that the main breaker only has 80% capacity of the rated value (i.e. 160 amp load).
    I would agree if all the loads were continuous - but in the calculations, continuous loads are already counted at 125% (so that 80% capacity is taken into account there) and all the other equipment has the appropriate demand factor applied. My opinion is that the existing 200 AMP main breaker is sufficient for this restaurant.

    If i am wrong, can this situation be rectified by replacing the existing 80% rated 200 AMP main breaker with a 100% rated 200 amp main breaker, while keeping all the conductors from the transformer to the panel? or would something else have to be done.

  2. jar546

    jar546 *****istrator

    Oct 16, 2009
    Likes Received:
    The rating of your conductors is more important than the rating of the OCPD. The 200 main is acceptable. You will find the actual loads to be a lot less than what is calculated.
  3. Builder Bob

    Builder Bob Sawhorse

    Oct 17, 2009
    Likes Received:
    ironic that in an receptacle circuit, that I can place as many devices on a circuit as I want, the important thing is that the size of the conductors is properly sized to match the level of protection provided. Construction practices and desires of contractors to prevent from making people made, tend to limit the number of receptacles on a circuit to about 10 devices.

    Before anybody pipes in, there are calculations for a certain number of VA to be used for each device however nowhere in the code does it specifically limit the number of receptacles on a general use circuit . (unless the NEC has changed that in the last few code cycles)

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