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    Default 20 amp duplex receptacle on 15 amp circuit?

    Is a 20A duplex receptacle allowed on 15A circuit?

    1) As the only receptacle?

    2) In parallel with other 15A duplex receptacles?

    This is the material I found which most directly addressed the issue, Mike Holt's Code Forum: Washer Receptacle, most discussion involves the reverse situation of one or more 15A receptacles on 20A circuits.

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    Last edited by Michael Thomas; 06-19-2008 at 09:33 AM.
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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Quote Originally Posted by Michael Thomas View Post
    Is a 20A duplex receptacles allowed on 15A circuit?

    1) As the only receptacle?
    Only receptacle on that circuit.

    From the 2008 NEC. (underlining is mine)
    - 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).
    - - - (A) (Jerry's note: This does not apply, this only applies to "having a rating in excess of 20 amperes".)
    - - - (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. (Jerry's note: This applies.)
    - - - - - Exception No. 1: A receptacle installed in accordance with 430.81(B). (Jerry's note: This does not apply.)
    - - - - - 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.(Jerry's note: This does not apply.)
    - - - - - - FPN: See the definition of receptacle in Article 100.
    (Jerry's note: The rest of this section does not apply.)

    Thus:
    - 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. (Jerry's note: This applies.)

    ~~~~~~~~~~~~~~~~~~~~~~~~~~

    2) In parallel with other 15A duplex receptacles?

    More than one (two or more) receptacles on the circuit.

    From the 2008 NEC.
    - 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).
    - - - (A) (Jerry's note: This does not apply, this only applies to "having a rating in excess of 20 amperes".)
    - - - (B) Receptacles.
    - - - - (1) (Jerry's note: This does not apply.)
    - - - - (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).(Jerry's note: This does apply.)
    - - - - - - Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle (Jerry's note: This states 15 amp receptacle on a 15 or 20 amp circuit with a maximum load of 12 amps - this does not answer the question.)
    - - - - - (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-and-plug-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.(Jerry's note: This does not apply.)
    - - - - - - Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.62(C).(Jerry's note: This does not apply.)
    - - - - - - Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits (Jerry's note: This states 15 amp receptacle on a 15 amp circuit.)
    - - - - - (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.(Jerry's note: This does not apply.)


    Thus:
    - 210.21 Outlet Devices.
    - - (B) Receptacles.
    - - - (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.
    - - - - Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits (Jerry's note: This states 15 amp receptacle on a 15 amp circuit or a 15 amp receptacle on a 20 amp circuit, *but not* a 20 amp receptacle on a 15 amp circuit.)

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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Quote Originally Posted by Jerry Peck View Post
    Thus:
    - 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. (Jerry's note: This applies.)
    Jerry,

    Correct me if I'm missing something, but while that prohibits a single 15A receptacle on a 20A circuit (15A receptacle ampacity is less than the potential 20A supplied), it does not seem (to me anyway) to address the situation where you have a 20A receptacle on a 15A circuit (20A receptacle ampacity is greater than the potential 15A supplied).

    It's the latter arrangement (20A on 15A) that I'm uncertain about.

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  4. #4
    Steve Lowery's Avatar
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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Boy! Wuz we ever paying attention on this one!!!
    Wouldn't that be the same as over sizing your wire, ie using 12 ga. wire on a 15 amp circuit?
    Over kill, expensive for sure but the breaker is the gate keeper here.


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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Quote Originally Posted by Michael Thomas View Post
    Correct me if I'm missing something, ... it does not seem (to me anyway) to address the situation where you have a 20A receptacle on a 15A circuit (20A receptacle ampacity is greater than the potential 15A supplied).
    (I've removed the underlining and used bold below)
    Quote Originally Posted by Jerry Peck View Post
    Only receptacle on that circuit.

    Thus:
    - 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. (Jerry's note: This applies.)

    ~~~~~~~~~~~~~~~~~~~~~~~~~~

    2) In parallel with other 15A duplex receptacles?

    More than one (two or more) receptacles on the circuit.

    Thus:
    - 210.21 Outlet Devices.
    - - (B) Receptacles.
    - - - (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.
    - - - - Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits (Jerry's note: This states 15 amp receptacle on a 15 amp circuit or a 15 amp receptacle on a 20 amp circuit, *but not* a 20 amp receptacle on a 15 amp circuit.)
    receptacle_rating_versus_circuit_rating.jpg

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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    "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"

    ---------

    1) Remove the negative condition to make that easier to understand:

    rating not less than = rating greater than or equal to

    for example not less than 1 = greater than or equal to 1

    2) Plug the simplified condition back into the sentence at the top of the post.

    "Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating greater than or equal to that of the branch circuit"

    3) In this case:

    20A is greater than or equal to 15A

    and

    A single 20A receptacle has an ampere rating greater than or equal to that of the 15A branch.

    So (it seems to me) a 20A receptacle is compliant on a 15A circuit...

    Last edited by Michael Thomas; 06-19-2008 at 01:03 PM.
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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    I was reading that the single receptacle was OK, but when used with more than one other receptacle on a 15 amp circuit, it was not. I wonder what the logic of that table is by not allowing the use of 20 amp receptacles on a 15 amp circuit? 15 or 20 amp receptacles are ok on a 20 amp circuit, but 20 amp receptacles are not ok on a 15 amp circuit.

    Jim Robinson
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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Michael,

    To clarify, this part you understand, right?

    Quote Originally Posted by Jerry Peck View Post
    2) In parallel with other 15A duplex receptacles?

    Thus:
    - 210.21 Outlet Devices.
    - - (B) Receptacles.
    - - - (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.
    - - - - Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits (Jerry's note: This states 15 amp receptacle on a 15 amp circuit or a 15 amp receptacle on a 20 amp circuit, *but not* a 20 amp receptacle on a 15 amp circuit.)
    You keep mixing numbers and re-using numbers for different things, 2) in your question is unrelated to 2) in your other post, following what you do not understand is difficult.

    There are two parts to your question, so the first thing to do is to eliminate the part you understand, reducing the question to 1 part - part 1).

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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Jerry,

    Yes, I agree that the table reference in 210.21 settles the question for circuits with two or more receptacles, thanks for posting that and the table.

    It's the single receptacle case I'm still unclear about, and I do think that changing the negative terminology to a positive helps clarify why...

    Michael Thomas
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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Michael,

    I wanted to make sure we were down to one question before going into that more confusing question.

    First, let me clarify your question by the title: "Re: 20 amp duplex receptacle on 15 amp circuit? ". The title eliminates the as yet unanswered question below because that ("duplex receptacle") puts "two or more" receptacle outlets on one circuit.

    The single receptacle on the single circuit (dedicated if you will) is that horse of a different color, and, no, I was not saying that it also needed to be the same (as when there are two or more receptacle outlets on a circuit).

    The circuit, as all circuits are, is required to be sufficient to carry the load served.

    The receptacle also is required to be sufficient to carry the load served.

    The overcurrent protection is required to be sufficient to carry the load served, and, with the circuit also being properly sized, the two match. That means that no more than what the overcurrent device will allow can be drawn through that circuit, which has conductors rated to match.

    Thus, installing a higher rated receptacle on a single receptacle dedicated circuit with properly sized overcurrent protection will not cause any harm per se.

    It may cause problems in that one may think that you can do more than you can, as in your example with the 20 amp receptacle on the single dedicated 15 amp circuit with a 15 breaker protecting it.

    Remember, the other table limits the amp load to 12 amps for a 15 amp circuit. Not that this will stop someone from plugging in a 16 amp draw window shaker (as an example) and tripping the breaker, then looking at the receptacle and thinking 'WTF is the problem here, that is a 20 amp receptacle.', then going out to the panel and finding that the breaker is only 15 amps, and that the conductors are only #14 AWG 15 amp rated.

    They are going to think the last person in who installed that 20 amp receptacle fooled them and took advantage of them ... and, in a sense, they did, either purposely or without thinking about it.

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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    I am inclined to say "no." Why? Because you're setting the stage for an overload.

    The whole purpose of the receptacle design is to prevent you from putting too large a load on the circuit. A 15 amp circuit clearly isn't intended to supply a 20 amp load. You're defeating the purpose of the design.

    That said .... I can think of one circumstance where I'm likely to install the "wrong" receptacle. Replacement GFI's. My reasons have nothing to do with the plug pattern, as such .... it's simply that I have been caught in far too many recalls of Leviton 15 amp GFI's. Thus, my truck has only the 20 amp (more reliable) models on it.

    So, you might say I'm breaking my own rule. All I can say in mitigation is that there is no known attempt to place a 20 amp load on the circuit.


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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    This came up, BTW, in the context of 20 Amp TSS outlet on a 15A circuit.

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  13. #13
    gek breganski's Avatar
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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    NEC Table 210.21(B)(3) is the answer to your question end of the story!


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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Quote Originally Posted by gek breganski View Post
    NEC Table 210.21(B)(3) is the answer to your question end of the story!
    Did you bother to read the posts above?

    The answer was already given above.

    Besides ... "end of story!" is so over used and passť, and it is really never true as there are so many exceptions to so many things that most of the time saying "end of story!" just show one is incorrect.

    Other than the above ... welcome to the board ... "end of story!".

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    Default Re: 20 amp duplex receptacle on 15 amp circuit?

    Quote Originally Posted by Jerry Peck View Post
    Only receptacle on that circuit.

    From the 2008 NEC. (underlining is mine)
    - 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).
    - - - (A) (Jerry's note: This does not apply, this only applies to "having a rating in excess of 20 amperes".)
    - - - (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. (Jerry's note: This applies.)
    - - - - - Exception No. 1: A receptacle installed in accordance with 430.81(B). (Jerry's note: This does not apply.)
    - - - - - 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.(Jerry's note: This does not apply.)
    - - - - - - FPN: See the definition of receptacle in Article 100.
    (Jerry's note: The rest of this section does not apply.)

    Thus:
    - 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. (Jerry's note: This applies.)

    ~~~~~~~~~~~~~~~~~~~~~~~~~~

    2) In parallel with other 15A duplex receptacles?

    More than one (two or more) receptacles on the circuit.

    From the 2008 NEC.
    - 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).
    - - - (A) (Jerry's note: This does not apply, this only applies to "having a rating in excess of 20 amperes".)
    - - - (B) Receptacles.
    - - - - (1) (Jerry's note: This does not apply.)
    - - - - (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).(Jerry's note: This does apply.)
    - - - - - - Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle (Jerry's note: This states 15 amp receptacle on a 15 or 20 amp circuit with a maximum load of 12 amps - this does not answer the question.)
    - - - - - (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-and-plug-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.(Jerry's note: This does not apply.)
    - - - - - - Exception No. 2: The ampere rating of a receptacle installed for electric discharge lighting shall be permitted to be based on 410.62(C).(Jerry's note: This does not apply.)
    - - - - - - Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits (Jerry's note: This states 15 amp receptacle on a 15 amp circuit.)
    - - - - - (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.(Jerry's note: This does not apply.)


    Thus:
    - 210.21 Outlet Devices.
    - - (B) Receptacles.
    - - - (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.
    - - - - Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits (Jerry's note: This states 15 amp receptacle on a 15 amp circuit or a 15 amp receptacle on a 20 amp circuit, *but not* a 20 amp receptacle on a 15 amp circuit.)
    Ahem, 20 amp duplex receptacle is NOT a SINGLE RECEPTACLE. It is two receptacle devices on a yoke.

    Commentary as to what applies and how applies is NOT correct in the context above, IMO, and IIRC this has been clarified by CMPs prior to and for 2008.

    You may NOT have multiple or a single(simplex) 20A face receptacles on a 15A circuit. You MAY have multiple 15A face 20A feed-through receptacles on a 20A circuit. A duplex 15A face 20A feed-through receptacle is TWO (duplex) receptacles on a yoke, and provides two outlets (to possibly "work" power).

    Last edited by H.G. Watson, Sr.; 09-30-2010 at 04:47 PM.

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