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Thread: General use receptacles on 30amp circuits

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    General use receptacles on 30amp circuits

    Why are general use 15 amp receptacles allowed on 20amp circuits but not on 30amp circuits? Is there any risk of doing such?

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    Why do 12 and under kids eat for free but not 13 year olds?

    There's not really that big of a size difference at that age.

    Seems someone decided there had to be a cutoff at some point.


    JAP>

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    Quote Originally Posted by jap View Post
    Why do 12 and under kids eat for free but not 13 year olds?

    There's not really that big of a size difference at that age.

    Seems someone decided there had to be a cutoff at some point.


    JAP>
    But why the cutoff? Electrical theory would have an answer.

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    My electrical theory is that 30a requires more metal in the current-carrying parts than 15/20a devices are made with, and OCPDs can't reliably protect the devices from overload damage.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

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    Maybe, in part, because most general use 15 and 20 amp receptacles are listed for 20 amp feed-through? There seems to be some coordination between the NEC and the NRTLs.
    Bob on the left coast.

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    Quote Originally Posted by LarryFine View Post
    My electrical theory is that 30a requires more metal in the current-carrying parts than 15/20a devices are made with, and OCPDs can't reliably protect the devices from overload damage.
    Quote Originally Posted by bkludecke View Post
    Maybe, in part, because most general use 15 and 20 amp receptacles are listed for 20 amp feed-through? There seems to be some coordination between the NEC and the NRTLs.
    That might be it then.


    But won't the receptacle itself be protected by overload? I can't see someone plugging in more then 4,600 watts of load let lone approaching that.

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    15a is really a 20a frame with a 15a face.
    The frame would melt on a 30a load after 145yrs.
    Why do we have digital tv when I watch black and white tv shows over the air on a 55" 4K tv? (Because they can't make a good tv show?).
    Why do I need all the DEF anti pollution crap on my truck when it makes the truck get lower fuel mileage, power, and support industry for it adds to pollution?

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    Quote Originally Posted by sameguy View Post
    15a is really a 20a frame with a 15a face.
    The frame would melt on a 30a load after 145yrs.
    Why do we have digital tv when I watch black and white tv shows over the air on a 55" 4K tv? (Because they can't make a good tv show?).
    It might boil down to the terminations. I mean said terminal splits in two, one up one down.

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    Quote Originally Posted by mbrooke View Post
    That might be it then.


    But won't the receptacle itself be protected by overload? I can't see someone plugging in more then 4,600 watts of load let lone approaching that.

    If the receptacles are daisy chained, the first one's in line will be taking the hit for whatever load is plugged in down stream.

    JAP>

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    Quote Originally Posted by jap View Post
    If the receptacles are daisy chained, the first one's in line will be taking the hit for whatever load is plugged in down stream.

    JAP>


    True, there is that one would need to avoid. But say you didn't or couldn't do that with the outlets at hand.

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