15A outlets on 20A circuits

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wrote:

That table is preceeded by the statement, which I provided and is shown above, that says it applies to circuits with TWO or more receptacles. If they wanted it to apply to ALL receptacles, including single outlet ones, they could have simply omitted the word TWO, but they did not. And the section right before it clearly covers the case of a SINGLE receptacle and allows a receptacle with a current rating equal to or greater than the circuit to be used.
It doesn't make a lot of sense to me, but that is what it says and it allows using a single 20 amp receptacle on a 15 amp circuit.
I see what you're reading, but there is no text that says any receptacle, single or duplex, can have a rating higher than the circuit feeding it.
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RBM wrote:

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RBM wrote:

[trader] I agree that 210 does not prohibit a single 20A receptacle on a 15A circuit
But a 20A receptacle is virtually never allowed under 406.3-B. It would make sense to at least point to 406 in 210. The logic is probably that 406 (Receptacles...) is the primary article and is modified by 210. There is a reference to 210 in 406.3.
Most people would not be dumb enough to want a 20A receptacle on a 15A circuit (there seems to be one exception).

[RBM] There is text that you can put a 20A receptacle on a 15A circuit.
There is no text in 210 that you can't have a higher rating, like 20A (or 50A, or 100A) as the single receptacle.
There is text in 406.3 that you can't put a 20A receptacle on a 15A circuit. This is what we all (except one) expect.
--
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I don't think the issue ever was what we expect. I would not have expected the code to allow a 20 amp receptacle on a 15 amp circuit either, which is why I brought it up in the first place. I also would not wire a circuit that way, because it's misleading at best. But what one expects and what is actually written in the code can be two different things.
I think there are actually three differing opinions on this subject. It looks like cl and I read the code as allowing a single 20 amp receptacle on a 15 amp circuit. Doug makes the claim, which I think is totally bogus, that the table in 210.21 (B) (3) says it is not allowed. But that is just plain wrong, because that table is preceeded by verbage that says it applies to circuits with two or more receptacles. I believe you and I agree on that point.
Then there is your position, which is that while not prohibited by section 210, it is prohibited by 406.3. That is a new point, which I had never heard used before. But let;s look at what that says. It doesn't actually say you can't put a 20A receptacle on a 15A circuit. What it says is this:
406.3 (A)
"Grounding type receptacles shall be installed only on circuits of the voltage class and current for which they are rated, except as provided in Table 210.21 (B)(2) and Table 210.21(B)(3)."
A 20A receptable is rated to handle 0 through 20 amps of current. A 15 amp circuit falls in that range, so I would interpret the above to mean that the 20A receptacle is permitted. Especially in view of the fact that when they specifically address the issue of a single outlet they could have just said that in the case of a single outlet you must use a receptacle with a rating equal to the circuit, but they did not and instead said this:
" 210.21 Outlet Devices. (B) Receptacles. (1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
Suppose instead of talking about receptacles, 406.3 talked about wire and said wire gauge shall only be installed on circuits of the voltage class and current for which it is rated. Would that mean that I couldn't use 12 gauge wire on a 15 amp circuit?
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wrote:

I don't think the issue ever was what we expect. I would not have expected the code to allow a 20 amp receptacle on a 15 amp circuit either, which is why I brought it up in the first place. I also would not wire a circuit that way, because it's misleading at best. But what one expects and what is actually written in the code can be two different things.
I think there are actually three differing opinions on this subject. It looks like cl and I read the code as allowing a single 20 amp receptacle on a 15 amp circuit. Doug makes the claim, which I think is totally bogus, that the table in 210.21 (B) (3) says it is not allowed. But that is just plain wrong, because that table is preceeded by verbage that says it applies to circuits with two or more receptacles. I believe you and I agree on that point.
Then there is your position, which is that while not prohibited by section 210, it is prohibited by 406.3. That is a new point, which I had never heard used before. But let;s look at what that says. It doesn't actually say you can't put a 20A receptacle on a 15A circuit. What it says is this:
406.3 (A)
"Grounding type receptacles shall be installed only on circuits of the voltage class and current for which they are rated, except as provided in Table 210.21 (B)(2) and Table 210.21(B)(3)."
A 20A receptable is rated to handle 0 through 20 amps of current. A 15 amp circuit falls in that range, so I would interpret the above to mean that the 20A receptacle is permitted. Especially in view of the fact that when they specifically address the issue of a single outlet they could have just said that in the case of a single outlet you must use a receptacle with a rating equal to the circuit, but they did not and instead said this:
" 210.21 Outlet Devices. (B) Receptacles. (1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
Suppose instead of talking about receptacles, 406.3 talked about wire and said wire gauge shall only be installed on circuits of the voltage class and current for which it is rated. Would that mean that I couldn't use 12 gauge wire on a 15 amp circuit?
OK Trader, After looking it over, and over, I think I'm starting to agree with you. The table is clearly prefaced by the text referring to other than single receptacles. I question if it may be an oversight as it sure doesn't make any sense to me, or you and Bud for that matter. Now I'm curious to get the opinion of one of the local electrical inspectors, not that that's necessarily definitive
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== "Suppose instead of talking about receptacles, 406.3 talked about wire and said wire gauge shall only be installed on circuits of the voltage class and current for which it is rated. Would that mean that I couldn't use 12 gauge wire on a 15 amp circuit? "
Of course you can use 12 gauge wire or even 10 gauge wire but not smaller gauge like 16 gauge which couldn't handle the full 15 amp load. IME 14 gauge would be very iffy as well although I have seen it used. Over-sizing the wire doesn't affect the 15 amp breaker from tripping if you over-load the circuit.
On all 20 amp split receptacles over the kitchen counters I used 10 gauge wire and 20 amp breakers. On all 15 amp receptacles I used 12 gauge wire and 15 amp breakers.
==
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Wow, that's good to hear! :) I know from all your posts over the years that you're a pro and know a lot more about the NEC than me, so I highly value your opinion and it's nice to hear I at least partially convinced you.
Here's a couple of links to Mike Holt's website, which is for electricians, inspectors, etc, with threads I found that discuss this issue:
http://forums.mikeholt.com/showthread.php?t=89149&highlight=single+receptacle+210.21
http://forums.mikeholt.com/showthread.php?t=122483&highlight=single+receptacle+210.21&page=3
Not saying that they are the definitive authority, but if you look at all the code issues they discuss there, it's obvious that there are some people there who are very knowledgable about the code. In the two threads, there is some initial disagreement and confusion, but at the end, the moderators and/or senior members come to the same conclusion, which is that a single 20A receptacle is allowed on a 15A circuit. I'm sure there are more threads on that site about it too.
I think the first time I heard about this was in some forum where an electrician was asking about it. He had gone to the supply house looking for a single 15A outlet for a job. He said the guy at the counter told him they no longer stock them, just the 20A, and that he could use that on a 15A circuit. Again, there was a lot of back and forth, but at the end the consensus was that code did allow it.
Another question. I think in one of your earlier posts you made some reference to using a higher rated receptacle for maybe an oven? Don;t recall exactly. But in looking through this issue on the web, I found some people saying that 50amp receptacles are sometimes used on 40amp circuits for ovens. Is that true? If so, how is that allowed? Unless there is some other section of the NEC that covers it, then it must be covered under the same 210.21 single receptacle section we are talking about, no? Meaning if it allows 50 on a 40, then 20 on a 15 is OK too.
Please let us know what the inspector has to say. Would be interesting to ask him the question first, then depending on the answer, show him the code sections and see what he says.
I'm still waiting for my apology from Doug.
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snipped-for-privacy@optonline.net wrote:

A 40A receptacle is rated to handle 0-40A. Would it be allowed on a 15A circuit?
The rule should be expected to be in the article on receptacles, which is 406.
The rule is (leaving some details out) that for 15 and 20A circuits, receptacles "shall be be installed only on circuits of the voltage class and current for which they are rated" (same as you quoted). On a 15A branch circuit you can only install a 15A receptacle and on a 20A circuit you can only install a 20A receptacle. You match the receptacle rating to the branch circuit rating. In 406.3-A it does not say 'voltage class and a current not less than the branch circuit'.
Then there is the exception - Table 210.21 (B)(2) and (B)(3). They allow a 15A receptacle on a 20A circuit. There is no reference to 210.21-B-1 (single receptacles).
There is not a problem with a 15A receptacle on a 20A branch circuit because listed plug-in equipment is apparently tested to be safe on 20A circuits (which it all can be plugged into). And a 15A receptacle is rated for 20A total.
The problem with installing a 20A receptacle on a 15A circuit is obvious to everyone (with one exception). It does not make sense the NEC would allow that (although the NEC does make mistakes). IMHO it is not allowed in 406.3-A. It is not explicitly allowed in 210.21-B-1. Would 210.21-B-1 allow a 40A receptacle on a 15A circuit?
But there is a difference. While 406.3-A is specific to 15 and 20A branch circuits, 210.21-B-1 (single receptacle) is general, including for instance a 60A receptacle on a 40A circuit - allowed by 210 and not covered by 406-3-A. For 15 and 20A circuits use 406.3-A.

But 406.3 isn't about wire gauge and there are reasons to use a larger size wire.
There are obvious reasons (to most people) why you don't want a 20A receptacle on a common 15A circuit.
=================The Holt discussions did not consider 406.3.
--
bud--

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The answer according to 210.21 (B) (1) would be yes. Oh, no! And just when I got RBM switching over...

The key here is that one sentence: "receptacles shall be installed only on circuits of the voltage class and current for which they are rated". I see your interpretation of this and would agree that it is one possible interpretation of what it means and it is not an unreasonable interpretation. And I agree that interpretation would close the loophole. The other interpretation is that a 20A receptacle is rated to handle a 15A current too, so it can be installed as well. But, with all things considered, I would even go so far as to say that I would now lean more towards your interpretation. It does put things back into more logical space.

Agree, that table applies to circuits with more than one receptacle, which we all agree has never been an issue.

Agree.
Agree, that is one possible interpretation. But I'd say the alternate interpretation is still possible too.

Clearly the answer to that is yes. And I agree it makes even less sense than allowing a 20A on a 15A circuit.

That answers my question about the 50A oven receptacle being allowed on a 40A circuit and what allows it. So, your position is that 210.21 (B) (1) allows it. But then while 210 B 1 would allow using a 20A on a 15A circuit, 406.3 A disallows it because it specifcally applies to 15/20A circuits. That at least makes things logical and consistent. Of course though, we are left with the obvious, which is even if your interpretation is correct, the NEC does allow single receptacles with a higher amp rating to be used on circuits above 20 amps. So, I guess inquiring minds want to know, if they allow it on those higher circuits, what's so special about 20A and does 406 3 A really mean to prohibit it? Do you agree that even with your interpretation I could put a single 50A receptacle on a 30A circuit?

Someone should revisit this whole thing over there, bringing up 406.3 and see what they have to say and if it changes their opinion. And more importantly, you would think they would add some verbage to NEC 210.21 B 1 that spells out that for 15 and 20 circuits, the receptacle rating must be equal to the circuit rating. That would totally clarify it and end any possible confusion.
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snipped-for-privacy@optonline.net wrote:

As a single receptacle yes. The problem is that equipment that comes wit;h a 20A plug is real common.
And now for the monkey wrench. One of the ways to determine what the code panels had in mind is to look at the code change proposals and see what the code panels did with them. Last I looked, the record for changes was online back to at least the 2002 NEC.
For the 2008 NEC there was a proposal to change 210.12-B-1 (single receptacle) to require the receptacle be equal to the branch circuit rating. The argument was specifically about a 20A singe receptacle on a 15A circuit.
The code panel rejected the change. Their statement [with my comments] was: "The recommendation would be overly restrictive in the case of some larger receptacle applications that do not directly correspond to the standard ratings of overcurrent protective devices." [It is not difficult to allow this and limit a 20A receptacle on a 15A circuit.] "The panel notes that a 20-ampere receptacle installed on a 15-ampere branch circuit is protected within its rating." [The panel apparently does not care that you can plug in readily available devices that are over the circuit rating.]
So the code panel apparently has no problem with a 20A single receptacle on a 15A circuit. But IMHO this can be tagged under 406.3-A, and it appears to me that the code panel for 406 does not agree.
===============================One of the other posts in this thread, by you, looks at table 210.21-B-2, which limits the load at any receptacle (when there are 2 or more) to 80% of the circuit rating. I said there was a proposal to change that in a previous code cycle.
There were proposals for 2002 (the oldest one I looked at), 2005, 2008 and 2011 to eliminate the table or make it apply only to continuous loads (as the 80% rule is applied elsewhere in the code). All were rejected.
As I said before, one of the arguments always made is that UL lists equipment that may use up to 15A with a 15A plug (and similar for 20A). According to 210.21-B-2, you can't plug that equipment with a 15A plug into a 15A receptacle.
Disagreeing on one of the rejections, the UL representative said: "For multioutlet branch circuits, use of noncontinuous appliances rated at 100 percent of the branch circuit does not result in a hazard. All branch circuit components, such as the receptacles, branch circuit wiring, and the overcurrent devices, when used for supplying noncontinuous loads, are evaluated for service at 100 percent of their full rating."
Supporting one of the rejections, the panel comment was: "Questions regarding how this requirement has been applied to products rated more than 12 amps and provided with 15 ampere plugs should be addressed to the responsible listing organization." This is an obvious dig at UL.
From the comments, it appears that at least one other code panel does not agree. This code panel seems to not play well with others.
--
bud--

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Wow, how things keep changing. First I had RBM moving towards my original position that from what the code says, a single 20 amp receptacle is allowed on a 15 amp circuit.
Then, you had me leaning towards your position that while 210.21 allows it, 406.3 rules it out.
Doug, who tried to use a table that doesn't apply, well, we haven't heard from him anymore. Maybe he's working on that apology. :)
And now you found this true gem, where the guys that write the NEC, per their change deliberations, believe a single 20 amp receptacle is allowed on a 15 amp circuit and chose not do anything about it. I'd have to say that's the most definitive thing I've seen yet and unless trumped by something else, ends the debate.
Thanks for once again being honest and open. Since it didn't support your original position, lots of guys would have just not posted that. But by posting it, we all can learn. I also agree completely with your position that they could have allowed the 210.21 single receptacle section to apply only to receptacles larger than 20 amps, while eliminating using a 20A on a 15 circuit. I see their point in the case of larger receptacles not always matching the load/breaker you want to use. In the case of the far more common 20Amp outlets, it's primarily an issue of avoiding unnecessary confusion to the extent possible. And I can't see how allowing a 20A receptacle on any 15A circuit does anything buy cause confusion and encourage someone to plug something in to a receptacle marked 20 amps on a circuit that can't handle it and will trip the breaker.

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snipped-for-privacy@optonline.net wrote:

As I said, IMHO a 20A receptacle on a 15A circuit can be tagged under 403.6-A. Greg?

I agree. The problem, IMHO, is that there is a lot of equipment that can draw over 15A that has a 20A plug.
I don't see a problem with using a 30A twist lock receptacle on a 15A circuit. You don't get equipment with a 30A twist lock plug.
Note that the same code panel does not think that a 20A plug should be on equipment that has a rating of more than 16A.

IMHO this is a similar head-in-the-sand problem with the same code panel.
The arguments that are often made to change table 210.21-B-2 to apply only to "continuous" loads are: 1 elsewhere in the NEC the derate to 80% is for "continuous loads" 2 it is a requirement that regulates what happens after the inspector leaves and is unenforceable 3 UL listed equipment (probably only non-continuous) is readily available that violates the rule.
I agree with all 3 arguments.
I do not remember a rational from the code panel that made sense to me. One response is that UL is wrong - no reason why.
The only rule I offhand remember that is in enforced after the inspector leaves is access space in front of panels, which is in a new thread, and I believe is heavily enforced by other inspectors.
--
bud--

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wrote:

I would tag it and have the installer explain to me why he did it. I agree there is some ambiguous language in the text of 210.21(B)(3) but when 406.3(A) directly addresses table 210.21(B)(3) it seems clear to me. In reality, 240.4(D) builds enough safety into small conductors that you won't be burning your house down. They know people will keep plugging things in until the breaker trips, then unplug the clock and go on.
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On Oct 17, 12:10pm, snipped-for-privacy@aol.com wrote:

The problem is that 210.21(b)(3) clearly says it and the table apply to circuits with more than one receptacle. And everyone is in agreement that using a 20A outlet on a 15A circuit with more than one receptacle is not allowed. It's 210.21(b)(1) that addresses the issue of a single outlet.
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On Sun, 17 Oct 2010 11:40:01 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

That is why you would cite 406.3(A). There are other places in the code where a table is referenced from 2 different articles.
I agree this is ambiguous and can start an argument in a room full of inspectors. I would still ask the installer why he was doing it. If the answer is "it is what I had on the truck" I am going to say he needs the right part. I am not sure what answer would really make me happy. The reality is, in spite of all the posturing I see on these BBs, nobody really wants their project sitting idle while they engage in a fight they are probably going to lose, over something this easy to fix. That is the value of being able to have the fight in cyberspace. If enough people write a proposal they will clean up the language.
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wrote:

As usual a great find Bud. It is odd that they would leave two contradicting points in the book without some clarification
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wrote:

For me, 406.3A is the most confusing. If it were based solely on 210.21, it's clear that the table doesn't cover single receptacles, and that single receptacles must be rated not less than the circuit. 406.3A uses the term "of the voltage, class and current" , it doesn't say "not less than", or anything that offers flexibility, other than to use the table in 210.21B3, which is not applicable to single receptacles. In conclusion, I'm still scratchin my head, other than the fact that, while there is no danger in using a receptacle rated higher than the circuit, there is no practical reason to do it, and it could just lead to confusion.
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wrote:

A 20 amp receptacle is going to outlast even the hospital duty 15 amp receptacle under moderate to heavy use. Absolutely no reason you cannot use a 20 amp receptacle anywhere in your house that code allows it, or anywhere in the house PERIOD if code is not in effect. Just like there is nothing stopping you from using AWG 12 wiring throught the entire house. The entire house can be wired for 20 amp circuits, and protected by 15 amp breakers or fuses without posing ANY safety issues. There will be cost issues, and IF you attempt to plug in a 20 amp device the breaker will eventually trip. The advantage is, all you need to do is install a 20 amp breaker in place of the 15 and any outlet in the house can instantly become a 20 amp circuit.

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On Oct 14, 2:59pm, snipped-for-privacy@snyder.on.ca wrote:

I think everyone here, except possibly you, agrees at this point that in the USA, the ONLY place code MAY allow doing what you describe is on a 15A circuit with a 20A single outlet. That was what the discussion was about. NEC 210 clearly prohibits putting 20A receptacles on any 15A circuit with more than one outlet. So, to do what you suggest, you'd have to use a single 20A outlet, not a duplex one, and do a homerun back to the panel for each outlet. That indeed involves cost issues, because your basic 15A duplex outlet would now be replaced by two single outlets with two cable runs back to the panel and two 15A breakers. And the point to doing it would be? To confuse people who see a 20A outlet and think they can plug in a 16 to 20A load? And it's currently very much up in the air if code even allows it in the case of a single outlet. I'm starting to lean towards that it does not.

And if you thought you might want 20A outlets in the future, the reason for doing it the way you proposed, as opposed to just wiring the place with a 20A breaker, 20A outlets wherever you want them to begin with, which would cost less than half and give them to you right away, would be?
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On Wed, 13 Oct 2010 16:33:24 -0700 (PDT), snipped-for-privacy@optonline.net wrote:

It actually makes a lot of sense, as I stated in an earlier post. What does NOT make any sense is a 15 amp plug on a 20 amp circuit
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