20A GFCI circuit with 15A receptacles

[iwire]

Re: 20A GFCI circuit with 15A receptacles

Peg I also agree with the others, if you compare the same grade receptacle from the same manufacturer you will find that the 'guts' are identical.

15 amp receptacles are in fact 20 amp receptacles without the extra slot.

Here is a Hubbell 15 Amp Heavy Duty Specification Grade Duplex Receptacle.

Here is a Hubbell 20 Amp Heavy Duty Specification Grade Duplex Receptacle.

Inside these are the same.

Now take a look at a lower grade Hubbell duplex. This is still a much better receptacle than the $0.49 ones found at the bargain outlets, regardless of a 15 or 20 amp rating.

As you can see this grade is much less robust than the ones above.

So IMO the best way to get a good receptacle for your clients is to specify a grade not an rating.

There is no reason for 20 amp receptacles in a dwelling unit, have you seen any dwelling unit appliances that require a 20 amp receptacle?

[ October 08, 2005, 11:12 AM: Message edited by: iwire ]

 

[infinity]

Re: 20A GFCI circuit with 15A receptacles

There is no reason for 20 amp receptacles in a dwelling unit, have you seen any dwelling unit appliances that require a 20 amp receptacle

That an excellent point Bob. The only 20 amp appliances that I've seen in a dwelling are air conditioners. And we usually don't see them plug into a counter top receptacle.

 

[LarryFine]

Re: 20A GFCI circuit with 15A receptacles

Originally posted by infinity:

There is no reason for 20 amp receptacles in a dwelling unit, have you seen any dwelling unit appliances that require a 20 amp receptacle

That an excellent point Bob. The only 20 amp appliances that I've seen in a dwelling are air conditioners. And we usually don't see them plug into a counter top receptacle.

Not only that, they should also be single-receptacle circuits, which indeed do require a 20-amp receptacle if on a 20-amp circuit.

 

[bthielen]

Re: 20A GFCI circuit with 15A receptacles

The way I've understood this is in the design of the plug that is installed on an appliance rated for 15A or less. A 15A rated receptacle requires the hot and neutral spades to be parallel. The plug that is installed by the manufacturer of a 20A rated appliance will have the spades perpendicular to each other and therefore could not be inserted into a 15A receptacle. The OCPD is not intended for protecting the appliance, but the circuit. Since the entire circuit is rated for 20A, and the 15A receptacle would not serve a 20A appliance, it is properly protected.

The only thing I haven't quite figured out is how is the receptacle itself protected? If it is built to 20A standards as suggested, then why not rate it 20A? I've never fully understood why the industry rates devices for a current load and then the NEC is forced to derate them under certain conditions. Seems to me that the device is being over-rated for the sake of the sale and we must compensate for that short-coming. It has been my contention that if a device is rated to handle 15A, it should be able to handle 15A in all applications.

Bob

 

[LarryFine]

Re: 20A GFCI circuit with 15A receptacles

Originally posted by bthielen:
The only thing I haven't quite figured out is how is the receptacle itself protected? If it is built to 20A standards as suggested, then why not rate it 20A? I've never fully understood why the industry rates devices for a current load and then the NEC is forced to derate them under certain conditions. Seems to me that the device is being over-rated for the sake of the sale and we must compensate for that short-coming. It has been my contention that if a device is rated to handle 15A, it should be able to handle 15A in all applications.

Bob, they basically are. If you notice, for example, range and dryer plugs and receptacles, they're identical except for the shape of the neutral blade: straight on 50-a and L-shaped on 30-a.

Remember, too, that, for example, 15-a GFCI receptacles are rated for 20-a feedthrough. If there was an advantage to manufacturing 15-a receptacles with thinner conductive parts, they would no doubt do so.

As stated before, there's more to a receptacle's rating than its electrical capacity. A 20-a receptacle's slot shape represents the circuit's capacity, not the receptacle's.

 

[bthielen]

Re: 20A GFCI circuit with 15A receptacles

Is this part of the reason that the NEC does allow 15A receptacles to be installed on a 20A circuit; because the receptacle, even though it is designed to accept only 15A plugs, is internally rated to handle the 20A and therefore able to handle the circuit's short-circuit load?

Bob

[ October 11, 2005, 08:16 AM: Message edited by: bthielen ]

 

[ryan_618]

Re: 20A GFCI circuit with 15A receptacles

Originally posted by bthielen:
Is this part of the reason that the NEC does allow 15A receptacles to be installed on a 20A circuit; because the receptacle, even though it is designed to accept only 15A plugs, is internally rated to handle the 20A and therefore able to handle the circuit's short-circuit load?

Bob

I would think the short circuit current rating would be closer to 10,000 than to 20.

 

[bthielen]

Re: 20A GFCI circuit with 15A receptacles

Thanks for the correction, Ryan. Goof on my part. I was thinking of an overload to the receptacle's rating (15A) in the event that a 16A - 20A load would be applied. For example, if someone used one of those multi-outlet plugs and overloaded the receptacle, per its rating, but not the circuit itself.

Bob