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I am upgrading some 15A outlets on a 15A circuit. Can I install 20A outlets instead of 15A outlets? If not, why not?

Will a 20A outlet on a 15A circuit pass a home inspection? Or, is it not allowed?


I'm going to be plugging in a 14000 BTU portable air conditioner and it just seems like a good idea to have a 20A outlet to reduce heating in the outlet, even if the circuit is rated only for 15A.

NOT a duplicate of Would there be a problem installing 20A switches on a 15A circuit?, because I'm asking about outlets, NOT switches.

I don't want to violate any laws either or have problems when I go to sell the house. I am located in California, in the United States. The house is an HOA-controlled condo, but I own the condo. The outlets I'm adding will be in the garage, likely on a NON-GFCI line--I'll be tapping a new outlet off of the house's interior hallway, through the wall, into the garage for a single new receptacle in the garage. The circuit is rated at 15A. I was thinking of putting a 20A outlet. I'm not sure, but maybe this is supposed to be a GFCI-outlet too, since it's in the garage--not sure.

Update:

This Amazon product review seems relevant: it indicates putting a 20A outlet on a 15A circuit is a code violation (emphasis added):

This was titled and advertised as a 15 amp device, but is actually a 20 amp device. As such, it's against safety code to use if you are on a 15A circuit. I had to return this item and purchase a 15 amp version, as installation of this would have caused me to fail inspection.

19 May 2021: I just saw this related question too:

  1. Is it OK to have a 20 Amp receptacle on a circuit with 12 AWG wiring and a 15 Amp breaker?
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    if you want to reduce heating install a better outlet instead of a budget one.
    – Jasen
    May 19 at 4:50
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    Agree with @Jasen. 15 amp outlets are designed to function on 20 amp circuits. In most cases, there is little difference between a 15 amp outlet and a 20 amp outlet of the same grade other than the prong configuration. If you want to avoid heating, put in a $10 or $5 outlet instead of a $0.89 outlet.
    – DoxyLover
    May 19 at 5:12
  • @DoxyLover, I just added two $14 USB-capable outlets, and neither work. I found some replacements with high ratings but they are 20A outlets. Will a 20A outlet on a 15A circuit pass a home inspection? Both USB outlets I just installed, which don't work, have prong receptacles apparently that aren't properly pinched together (ie: not tight enough), so the prongs don't make contact. Seems odd a $14 brand-new outlet doesn't work (though its USB power outlets do). May 19 at 5:28
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    Are these $14 usb outlets name brand with UL listing? May 19 at 6:29
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I'm going to be plugging in a 14000 BTU portable air conditioner and it just seems like a good idea to have a 20A outlet to reduce heating in the outlet, even if the circuit is rated only for 15A.

That won't have any effect. The internals of both 15A and 20A outlets are made of exactly the same stuff.

That's due to a UL requirement that 15A receps must be able to carry 20A internally, so they can be used in 20A circuits per 210.21.

enter image description here

If anything, 20A outlets are a bit worse, because the neutral wiper cannot be ful-width, since it must have a notch in it for the 20A sideways neutral. Of course many 15A receptacles use the same stampings.

Putting a 20A recep on a 15A breaker would defeat the entire purpose of 20A plugs being a different shape. So obviously that has to be a code violation. You don't want to plug a 20A-requiring appliance into a 15A circuit, because it would definitely overload, and ALL safety margin would rest on the breaker tripping.

If you wonder why a "single point of failure" is a bad safety strategy, watch aviation accident investigation videos.

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    Can you add a link where you got that screenshot? May 19 at 6:51
  • @GabrielStaples, you can ready the NEC for free on nfpa.org, but deep linking isn't possible. Table 210.21(B)(3) is referred to from 210.21(B). May 19 at 16:10
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    @Gabriel here. May 19 at 19:10
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No 20A receptacle on a 15A circuit allowed.

15A receptacles can safely take a 20A current, so in terms of heat development in the outlet or receptacle, it's the same anyway.

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  • Then why are 20A outlets made at all if 15A outlets already take 20A? Certainly 20A outlets can take more load than 15A outlets, no? Maybe they take 25A then? May 19 at 5:26
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    @GabrielStaples 20-amp outlets are designed to accept either 15-amp (NEMA 5-15) and 20-amp (NEMA 5-20) plugs. They differ in that the 20-amp plug has one prong turned 90 degrees. Therefore, the 20-amp outlet has a T-shaped slot to accept either.
    – DoxyLover
    May 19 at 5:39
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    @GabrielStaples the 20A T-slot is allowed if the breaker is 20A. A 20A device has a plug and chord rated for 20A (fryer, toaster, hair dryer..). It's not for the receptacle's protection. The T-slot prevents plugging a 20A device into a 15A circuit and rendering it thus inoperable.
    – P2000
    May 19 at 14:35

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