General use receptacles on 30amp circuits

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mbrooke

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

jap

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Electrician
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>
 

mbrooke

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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>

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

LarryFine

Master Electrician Electric Contractor Richmond VA
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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.
 

bkludecke

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Big Bear Lake, CA
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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.
 

mbrooke

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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.

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.
 

sameguy

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New York
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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?
 

mbrooke

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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?).

It might boil down to the terminations. I mean said terminal splits in two, one up one down.
 

jap

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Electrician
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>
 

mbrooke

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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.
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
So you're asking about a single 15a receptacle on a 30a breaker? :eek:hmy:

To me, that's worse than the same load shared by several receptacles on a 30a circuit.
 

jap

Senior Member
Occupation
Electrician
I've got another theory.

Because the screw terminals are not rated for the larger wire, and, scabbing on a piece of #12 to a #10 to make it happen would be a code violation.

JAP>
 

mbrooke

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I've got another theory.

Because the screw terminals are not rated for the larger wire, and, scabbing on a piece of #12 to a #10 to make it happen would be a code violation.

JAP>


You don't create one rule to prevent the violation of another- at least I believe that is the intent of the NEC.
 
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