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Thread: number of receptacles on a circuit

  1. #1

    number of receptacles on a circuit

    could someone please help me find the location in the code book on how many 20 amp receptacles can be installed on (1) 20 amp breaker

    also a method to add a combined number of receptacles

    15 and 20 amp

    Thanks
    Robert

  2. #2
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    Re: number of receptacles on a circuit

    is this a residential application ?

  3. #3
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    Re: number of receptacles on a circuit

    This has been discussed several times on this Forum. May I ask you to do a word search, and see if you can find your answer?

    This might be a good topic for inclusion in the FAQ section. However, given the strongly opposing points of view that have been expressed on this topic, I don't know if I would be willing to write up the "correct" answer for the FAQ.
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

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    Re: number of receptacles on a circuit

    Here are a few threads you can check out.

    1

    2

    3


    Roger
    Moderator

  5. #5
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    Re: number of receptacles on a circuit

    Per NEC 220.14(I) each receptacle on one yoke shall be calculated at not less than 180va. A 20 amp breaker serving non-continuous loads has a capacity of 20 amps time 120 volts or 2400va. 2400 divided by 180 is 13.33 so you can put 13 receptacles on one 20 amp breaker. I assume each breaker to be continuously loaded so the max available current on a 20a breaker is 16 amps. I look at the area the receptacle is serving and decide if 180 is OK. Also putting 13 receptacles on a circuit doesn't allow for adding any more receptacles in the future. I limit the receptacles to about 6- 8 on a circuit.

  6. #6
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    Re: number of receptacles on a circuit

    By bh:

    Per NEC 220.14(I) each receptacle on one yoke shall be calculated at not less than 180va.
    That's 220.3(B)(9) in the 2002 and it doesn't apply to dwellings.

    [ August 09, 2005, 12:48 PM: Message edited by: physis ]
    Sam, San Francisco Bay Area

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    Re: number of receptacles on a circuit

    Killer 76
    We need to know if it's for residential,commerial or industial.
    Jim

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    Re: number of receptacles on a circuit

    If it's residential, put as many as you can afford to buy on the circuit.

    Other than residential, 220.3(B)(9) as pointed out by Physis.

    Bh, why would you consider a receptacle circuit continuous unless you knew specifically what the use was?

    Roger
    Moderator

  9. #9
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    Re: number of receptacles on a circuit

    Originally posted by roger:Bh, why would you consider a receptacle circuit continuous unless you knew specifically what the use was?
    I would never treat a receptacle circuit as "continuous," regardless of what is plugged in, if by that you mean that you would multiply the 180 VA times 125%. Our design and installation efforts are based on 180 VA, not on any potential future use of the receptacle.

    But homeowners have a constraint of which they are likely unaware. If I had a single, large, plug & cord, not-permanently mounted item (e.g., hair dryer) plugged into a 20 amp receptacle outlet that is part of a 20 amp branch circuit, that one item is not allowed to be more than 16 amps (1920 VA). But I can still plug 4 more amps worth of other stuff (480 VA) into other receptacles on the same branch circuit.
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  10. #10
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    Re: number of receptacles on a circuit

    Charlie
    Just to be difficult.
    16A is 1920VA at 120V. If the load is a hair dryer, it can be rated by UL as 2000W at 125V maximum. Because it is primarily a resistive load using it at 120V would reduce it's current draw as well as it's heat output.
    Just because you can, doesn't mean you should.

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