I added an outlet to a bathroom. When I pulled the outlet, which was a 15A, that I was going to tie into it was wired with a #12. I checked the circuit and it is a 20 AMP circuit. It was part of a bathroom that was part of a GFCI. I thought maybe since the was a ground fault that it was okay to have the 15A outlet on a 20A.

I did a little more looking around comparing the circuit to the outlets. It appears that the 20A circuits are all wired with 15A outlets.

Is this a code violation or safety hazard?



  • @statueuphemism that link is about a 15 amp circuit. This is about a 20 A circuit which I take to mean it is on a 20 A breaker. – JimmyJames Oct 21 '16 at 14:30
  • @JimmyJames In Tester101's answer, he shows table 210.21(b)(3), which indicates that a 20 A circuit can have 15 or 20 A receptacles – mmathis Oct 21 '16 at 14:31
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    @JimmyJames Good catch, I misread, but I know it's been asked before. Correct reference is: diy.stackexchange.com/questions/12115/… – statueuphemism Oct 21 '16 at 14:37
  • @mmathis OK. Can you clarify what is meant by the comment that follows? "It's also good to remember, that the NEC does not view a duplex receptacle as a single receptacle according to the definition of a receptacle." – JimmyJames Oct 21 '16 at 14:37
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    Basically, on 15A circuit with multiple receptacles, the maximum permissible single load = 80% * 15A = 12A. So if you had an appliance that drew 12.1-15A from one of the receptacles on a multi-receptacle 15A circuit, this is the unsafe code violation referred to in the article. However, the maximum permissible single load of a receptacle on multi-receptacle 20A circuit = 80% * 20A = 16A. This means that you can safely operate an appliance which draws 15A through a 15A receptacle on a multi-receptacle 20A circuit. – statueuphemism Oct 21 '16 at 15:42

Folks, folks...

15A outlets are totally legal on 20A circuits.

Because the NEC makes an exception specifically for that (National Electrical Code): enter image description here

The exception is by careful plan. It would be stupid for electricians to have to carry two types of receptacles on their truck. So UL (the listing agency) requires all 15A receptacles to have internal circuit paths good for 20A. This allows the same receptacle to be used in both 15A and 20A circuits. It also allows two appliances totaling 20A to be plugged in at once, even though each appliance is less than 15A. The extra copper is trivial, they still manage to sell these things as cheap as 60 cents apiece.

If you want a quality receptacle, buy one. You can buy quality NEMA 5-15 (Mr. Horrified) for $3 and up. You don't need to buy a NEMA 5-20 (Mr. Winky) to get quality, but it assures quality since cheapie 5-20's are not commonly made.

  • Could you quote the section of the UL standard section which requires all 15A receptacles to have internal circuit paths good for 20A? I know I've seen scattered postings on the internet that the innards are typically the same, but this is the first I've heard of it actually being a UL requirement. – statueuphemism Oct 21 '16 at 19:27
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    Those docs are intended for component manufacturers, not field installers, and are priced accordingly. An older pirated one found loose on the Web shows it at UL 498 section 107 in several places, particularly 107.2 Each receptacle provided with means for through-wiring on a branch circuit is also to be subjected to a terminal temperature test at a current of 20 A. – Harper - Reinstate Monica Oct 21 '16 at 21:04
  • Ah, so you just meant the through-current or "pass through" to the rest of the branch circuit. I thought you were indicating that the entire receptacle (particularly at the cord-connection interface) was identical in terms of its current capacity for 15A and 20A receptacles (and it very may well be). You piqued my interest, so I got access to the 2014 copy of UL 231 (Power Outlets). A cursory look-through didn't turn out anything, but I'll see what I can find related to this when I'm up for some more in-depth reading. – statueuphemism Oct 21 '16 at 21:19
  • @statueuphemism I believe UL231 might be the wrong standard -- UL498 is what you want. – ThreePhaseEel Oct 21 '16 at 22:27
  • @statueuphemism I just showed one highlight; 498 says more. I suspect on duplex outlets they are rated for 20A on any path 20A could happen (presuming the 5-15 keying prevented >15A over any particular outlet.) Otherwise a 20A breaker would not protect it. It wouldn't surprise me if some lines of outlets had identical guts in their 15 and 20A offerings; that wouldn't be the cheapies though. – Harper - Reinstate Monica Oct 21 '16 at 23:22

Most 15 A receptacles are rated for 20 A pass through. So, if you plug something into it, it has to be less than 15 A, but it can safely be installed on a 20 A circuit.

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    If you plug something into it that pulls more than 15 amps, the 20A breaker will not flip. – JimmyJames Oct 21 '16 at 14:26
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    @JimmyJames If something pulls more than 15A, if properly manufactured, it should have a plug with a horizontal plug that fits into 20A outlets, but does not fit into a 15A outlet. – statueuphemism Oct 21 '16 at 14:29
  • @statueuphemism Most outlets have two receptacles. – JimmyJames Oct 21 '16 at 14:31
  • @JimmyJames That is correct: Two receptacles rated at 15A each with a 20A pass-through as per mmathis answer. Tester101's answer from diy.stackexchange.com/questions/12115/… addresses it more thoroughly with code references. – statueuphemism Oct 21 '16 at 14:36
  • @statueuphemism don't use any extension cords, or power strips etc. See the answer farther down from that link. – JimmyJames Oct 21 '16 at 14:44

This is code but I would change the outlets. Outlets are cheap and easy to replace. Why chance it?

So you can leave this but don't plug more than 2 or more things into one of the outlets that exceed 15 Amps through extension cords or the like. Technically, doing that isn't code but most people who are not electricians don't realize they have to know about this issue. It's crazy that they make people hard-wire smoke detectors in (because people yank the batteries) but expect these same people to not overload an extension/splitter.

Make sure all the other occupants in the house know not to use these:

enter image description here

Or you could just change out the outlets to 20A rated. Another option is that you could change the breaker to a 15A. That will reduce the overall capacity of the circuit, though.

  • -1 It adds up quickly if you're replacing all the outlets in your home and it is unnecessary. – statueuphemism Oct 21 '16 at 14:24
  • @statueuphemism if it's just the one circuit then there should be no more than 8 outlets, if I am not mistaken. – JimmyJames Oct 21 '16 at 14:30
  • -1 While it may be true, it doesn't answer the question – mmathis Oct 21 '16 at 14:37
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    @JimmyJames Even if you upgrade to a 20A receptacle, you have the same potential problem if someone plugs in a single receptacle to multi-receptacle converter like the plug you show. 2 receptacles @ 15A = 30A which is more than either a 15 or a 20A receptacle is rated. – statueuphemism Oct 21 '16 at 15:50
  • @statueuphemism At which point the 20 A breaker should open the circuit. That doesn't necessarily happen if you pull between 15 and 20 (realizing this is not perfectly precise) through a 15 A receptacle. – JimmyJames Oct 21 '16 at 15:54

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