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I have noticed in a few different houses in Oklahoma that 20 amp breakers are used, but all of the outlets and switches only seem to be rated for 15 amps. This goes against everything I know to be proper and safe. The wire used is 12 gauge, so at least that is fine.

I have started to replace all of the switches and outlets with the decorative switches (the rectangular ones) and have found it very difficult to find switches that are rated for 20 amps. As for the outlets, I have can find them rated for 20 amps, but not in the 10 packs that I see for the 15 amp versions.

Is there something about electrical code that I am missing?

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I think I've seen your exact question, but this question and it's answers should provide enough details. –  BMitch Feb 8 '12 at 23:52
    
@BMitch I am not referring to the shape of the plug, but rather the actual current rating. An outlet rated for 15 amps could have multiple devices on it pulling more than a total of 15 amp. Since the breaker is 20 amps, I could be constantly pulling more then the outlet is rated for. I have been able to find outlets that have the 15 amp shape, but are rated to handle 20 amps, but these are the ones that I am having a hard time finding (at least for a comparable price to the 15 amp ones). –  Kellenjb Feb 9 '12 at 0:17
    
However, if there is a question exactly as mine I would be fine with that. I did some search before I asked and didn't find anything. –  Kellenjb Feb 9 '12 at 0:18
    
And one more note, I did find it interesting that NEC says you can have 15amp circuits in living spaces and bedrooms and a minimum of two 20amp circuits in kitchens with home run. The smallest breaker in the houses here are 20 amps, and this includes in bedrooms and living areas. –  Kellenjb Feb 9 '12 at 0:20

4 Answers 4

up vote 12 down vote accepted

NEC 2008

210.21 Outlet Devices. Outlet devices shall have an ampere rating that is not less than the load to be served and shall comply with 210.21(A) and (B).

(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.

Exception No. 1: A receptacle installed in accordance with 430.81(B).

Exception No. 2: A receptacle installed exclusively for the use of a cord-and-plug-connected arc welder shall be permitted to have an ampere rating not less than the minimum branch-circuit conductor ampacity determined by 630.11(A) for arc welders.

(2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).

Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle

(3) Receptacle Ratings. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or where larger than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.

Exception No. 1: Receptacles for one or more cord-andplug-connected arc welders shall be permitted to have ampere ratings not less than the minimum branch-circuit conductor ampacity permitted by 630.11(A) or (B) as applicable for arc welders.

Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.62(C)

Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits

(4) Range Receptacle Rating. The ampere rating of a range receptacle shall be permitted to be based on a single range demand load as specified in Table 220.55.

If it is a single receptacle on a 20 Amp circuit, it must be a 20 Amp receptacle (aside from the 2 exceptions). If there are multiple receptacles on a 20 Amp circuit, the receptacles can be either 15 or 20 Amp (aside from the exceptions).

This is to allow You to have multiple devices plugged in drawing less than 15 Amps each, but the total draw on the circuit may be greater than 15 Amps.

NOTE:
Keep in mind that NEC defines a receptacle as follows.

Receptacle. A receptacle is a contact device installed at the outlet for the connection of an attachment plug. A single receptacle is a single contact device with no other contact device on the same yoke. A multiple receptacle is two or more contact devices on the same yoke.

So a duplex receptacle would be considered two receptacles, according to this definition. Which means you can install a single 15 Amp duplex receptacle on a 20 ampere circuit, without violating this code.

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Does this mean that a 20A bathroom circuit, having only one receptacle, must use a 20A GFCI device? –  Matthew Nov 24 '12 at 0:22
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@MatthewPK Yes. But don't forget, a duplex receptacle is not a single receptacle. So you can have a single 15A duplex receptacle on a 20A bathroom circuit. –  Tester101 Nov 26 '12 at 12:03
    
I don't think you've got this right, Tester101. If a single receptacle is on a 20-amp circuit, it must have a rating "not less than that of the branch circuit". This means a 20-amp or greater device is fine, but you're saying it must be exactly 20-amp rated. Same for the case where the branch circuit is driving multiple outlets or multiple receptacles. –  MikeB Oct 12 at 16:26
    
@MikeB Table 210.21(B)(3) clearly says that on a 20 ampere circuit 15 or 20 ampere receptacles are allowed. Also remember that a duplex receptacle counts as two receptacles, not one. –  Tester101 Oct 12 at 16:35
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Also, you can't have a 30 ampere receptacle on a 20 ampere circuit, because that would allow you to plug in a 30 ampere device. If it's a single receptacle on a 20 ampere circuit, the receptacle must be rated 20 amperes. –  Tester101 Oct 12 at 16:54

SteveR...

"Apparently a 15A receptacle is safe to use @ 20A"

Scott...

This is incorrect. It is not safe. You are allowed to use a 15 amp rated outlet on a 20 amp circuit simply because it is expected that the cord that's plugged into the outlet should not exceed 15 amps (by code). The current conducted through the front of the outlet is added to the 20 amp branch total at the wire, not within the outlet itself. In theory, if heat dissipation isn't an issue, you could install a 15 amp rated duplex outlet on a 30 amp circuit and be just as safe because the top could handle 15 amps and the bottom could handle 15 amps. Yet nowhere within the receptical would it conduct 30 amps because the current is added at the conducting wire.

If you have an applicance with a 15 amp cord that's drawing > 15 amps, it is in violation of the code. There should not be any such appliances on the market. Appliances which draw > 15 amps should have a 20 amp or higher cord and plug. Since power strips are supposed to have built in breakers, thier cords should not exceed 15 amps. Unfortunately, sometime people exceed the 15 amp rating of a 15 amp receptical by using an extention cord with a triple input where the current sum of the individual cords > 15 amps. It is recommended that you do not do this since it's a fire hazzard and it violates the code. However, just because this is possible, doesn't mean it's the fault of the code. You can't blame the code because people choose not to follow instructions.

I don't want the NEC to try to make the code idiot proof. Such an effort would eliminate many many convienient electrical products which are safe when used as directed.

Kellenjb...

"But lets say I plug in a power strip and pull more than 15 amps, sounds plausible to me and not very safe."

Scott...

You are correct, it is not safe.
If you are able to do so, then you certainly do have a problem. If your power strip has a standard 15 amp (14 awg) cord and plug, then it is supposed to have a built in 15 amp breaker. In your example, your breaker isn't functioning properly and that is not the fault of the code. If you don't have a built in 15 amp breaker, then your power strip is in violation of the code and by using it, you are violating the code.

Kellenjb...

"Thanks for the answer, but it didn't really get to the point of my question. I fully understand that if you add up the possible current that can be drawn from each outlet, you can go over the current rating of the breaker. I just don't understand why it is allowed to have the situation where one outlet can have more current pulled on it then what the outlet can handle. I would hope the breaker would trip before this point in time."

Scott...

Let me be frank. I don't know exactly why the NEC chose to allow this. I could speculate based on legitamate reasons but I won't now. What I can say is what I stated above. it's possible to exceed the 15 amps when using an extention cord with more than one receptical on it whereby summing the current of multiple applicances totalling > 15 amps (violating the code). Doing so is contrary to the instructions of the extention cord. It is not safe and should not be done. You should be able to discern when you reach the 15 amp limit by adding up the current of each appliance on such an extention cord and not exceed 15 amps (or use current = power/voltage).
Now I'll exclude such possibilities of improper practices from further discussion or I'll never get done.

An outlet rated for 15 amps should only have 15 amps conducted through the front of it via a 15 amp (14 awg) cord.
Let's say you have a duplex outlet and you draw 15 amps on the top and 5 on the bottom, totaling 20 amps. There is no part of the outlet that's conducting 20 amps. The 20 amps should be conducted through the attached 12 awg wire only. If you have two different duplex outlets daisy chained (in parallel) whereas the first conducts 15 amps and the second condusts 5 amps, the current is added at the wire, not the outlet.

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Keep in mind, in addition to a power strip and cord connecting a single device, you can get a power splitter from the hardware store without any breaker, and you can also plug in two 15 amp devices into a duplex receptacle. This is why they often rate a 15 amp receptacle at 20 amps. You can't plug in a 20 amp device with the side tang, but the receptacle is designed for it anyway, and likely assembled from the same parts, just with a different face. –  BMitch Nov 21 '12 at 11:56
    
It seems a bit crazy to talk about how using an extension cord breaks code so should not be done. How many average people know this. I would imagine there isn't a single house in any of our towns where this isn't done regularly. People have no idea what code says and since we've all grown up with extension cords with multiple outlets in them, no one would have any idea not to use them as we always have. Something's gotta be missing here.... –  user12791 May 1 '13 at 19:22
    
Many stores sell devices to convert a duplex outlet into six, and many such devices are rated for 15A but lack any sort of circuit protection. If both the multi-tap device and the underlying outlet could handle 20 amps continuously without overheating, a 20 amp mains breaker would seem adequate protection, but if not I would think a 15-amp breaker should be required someplace for safety. –  supercat Jan 27 at 23:49
    
Also, while devices which are designed to draw more than 15 amps should certainly have high-current-style plugs, what about devices which as a consequence of malfunction draw more current than designed, but not so outrageously much as to instantly trip a 20-amp breaker? –  supercat Jan 27 at 23:56

if memory serves they call this Diversity. The expectation is that not all outlets served by the breaker will be at full current draw 100% of the time, there is a limitation on the number of outlets per floor area too yet it's still possible to have enough 13A outlets on one 32A ring to exceed 32A. In practice it won't happen and if it did, well that's what the breaker is for. I should add this is in the United Kingdom but I expect there is a similar term for over the pond albeit lower voltage, higher current then here.

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Thanks for the answer, but it didn't really get to the point of my question. I fully understand that if you add up the possible current that can be drawn from each outlet, you can go over the current rating of the breaker. I just don't understand why it is allowed to have the situation where one outlet can have more current pulled on it then what the outlet can handle. I would hope the breaker would trip before this point in time. –  Kellenjb Feb 11 '12 at 22:32
    
Well in the UK the plug that goes in the outlet is fused at the correct rating for the appliance so it is that that prevents the outlet being overloaded. The breaker prevents the supplying circuit to one but usually more outlets being overloaded, choosing the rating of that breaker is where Diversity has to be taken into account. –  dannix Feb 11 '12 at 22:55

It appears to be permitted to use a 15A receptacle with 20A breaker and 12 AWG wire. The reasoning is that you can't plug a 20A appliance into the 15A receptacle because of the side tang.15A receptacle on 20A breaker.

Apparently a 15A receptacle is safe to use @ 20A. The thinking is that more appliances are drawing more power these days and 15A is to low. This seems to be especially true with kitchen appliances. If you think of a kitchen appliance that uses 1750W, that exceeds 12A (15A @ 80%) rating of a 15A circuit! It should hold if it's the only appliance, but will tax the breaker at a load of 14.6A. It would be safer on a 20A circuit, at 14.6A load (resistive).

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But lets say I plug in a power strip and pull more than 15 amps, sounds plausible to me and not very safe. –  Kellenjb Feb 9 '12 at 13:56
    
I agree, but that can also happen with a 20A receptacle. The circuit is still protected for 20A (with 12AWG wire), and they are saying a 15A receptacle can handle 20A okay. See my edit. –  SteveR Feb 9 '12 at 14:17
    
At least with a 20A receptacle on a 20 amp breaker, if you exceed 20 amps the breaker trips and prevents too much current flowing through the receptacle. If all 15A receptacles can actually handle 20 amps this would be good to know, but based off of what I have seen on the boxes, not all advertise that they can handle 20 amps. –  Kellenjb Feb 9 '12 at 14:52
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You can't draw 20 amps through a single 15 amp outlet. You can draw 20 amps through 2 or more daisy chained 15 amp outlets. With daisy chained outlets the likelihood of drawing all 20 amps through one outlet is minimal. This is why it is allowed to use 15 amp outlets. –  Brad Gilbert Feb 9 '12 at 15:12
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@BradGilbert - You can draw as much amperage though a 15 amp receptacle as you want, at lease til the circuit breaker trips or the receptacle or wire fails. Their is nothing in a receptacle or switch which regulates how much ampacity that goes through it, other than physics. I guess you can compare it to either speed limits or speedometers. If a car's speedometer only shows 80 mph, can it not go faster? –  lqlarry Feb 11 '12 at 1:18

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