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#96128 - 11/06/05 06:42 AM 20A receptacles on a 15A circuit.
cgw Offline
Member

Registered: 07/29/04
Posts: 133
Loc: Rochester NY
Do you agree or disagree that 20A receptacles can not be put on a 15A circuit based on Table 210.21(B)(3)?
The circuit is 15A because it has been derated due to too many conductors in a conduit.

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#96129 - 11/06/05 07:07 AM Re: 20A receptacles on a 15A circuit.
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
15 amp circuits that supply multiple receptacles can not feed 20 amp receptacles.
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Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#96130 - 11/06/05 07:08 AM Re: 20A receptacles on a 15A circuit.
George Little Offline
Member

Registered: 01/18/04
Posts: 1492
Loc: Michigan USA
The text in 210.21(B)(3) seems to be rather clear and points to the Table 210.21(B)(3) and I would say 15a. receptacles on 15a. circuits.
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#96131 - 11/06/05 02:11 PM Re: 20A receptacles on a 15A circuit.
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
While improper, it is almost certainly harmless. There are very few genuine 20Amp plugs out there. If one were ever to be put on your circuit, it would pop pretty quickly.

BTW, I am shocked that you just didn't pull bigger wire. #12 THHN, above ground, derates to 21Amps with 9 conductors. #10 derates to 20Amps, above ground, with 20 conductors.

If this is a commercial job most customers want a consistent look for their receptacles.
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#96132 - 11/06/05 03:28 PM Re: 20A receptacles on a 15A circuit.
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
 Quote:
While improper, it is almost certainly harmless.


That is not relevant in a forum titled NEC & other Code issues

For what it is worth a 20 amp load on a 15 amp breaker may never open the breaker, it will certainly not open quickly.

Bob
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#96133 - 11/06/05 05:05 PM Re: 20A receptacles on a 15A circuit.
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
I can't really respond as to the "legal line" of the NEC. Let's look at it another way first.....

A 15 amp circuit, for whatever reasons, is designed to deliver 15 amps (12 continuous).

An appliance with a 20 amp plug has been deemed, for whatever reasons, to require more than what a 15 amp circuit can deliver.

It seems likely, to me, that the appliance will suffer from an inadequate feed. It also seems likely that the appliance will, over time, damage the circuits.

After all, how often do you see wire insulation that has been destroyed, simply because someone insisted on using a too-large light bulb?

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#96134 - 11/08/05 03:13 PM Re: 20A receptacles on a 15A circuit.
George Offline
Member

Registered: 02/23/02
Posts: 380
Since there are no legal requirements on truth in labeling, it is legal to take an appliance that draws 20amps and place a 15amp plug on it.

My lawnmotor has a 15amp plug and draws 13amps, more than what is allowed on a 15ap circuit. My bandsaw is rated at 1.5hp with the corresponding current draw and a 15amp plug. In reality it is 2hp. Both should have 20amp plugs.

In addition, since a duplex 15amp recept can have 2 15 amp devices (30amps total) plugged in ...

I expect that 20amp recepts on 15amp circuits are not only harmless, but the same effect is common.

But again it is a violation of the NEC unless you hire an engineer and have nhim approve it,

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#96135 - 11/08/05 03:54 PM Re: 20A receptacles on a 15A circuit.
earlydean Offline
Member

Registered: 12/22/03
Posts: 749
Loc: Griswold, CT, USA
An engineer's approval of a violation does not make the violation go away. It is still a violation. The NEC (310.15(C))does allow an engineer to certify the maximum ampacity of a conductor using the formula printed there. Nowhere, that I can find, does the NEC allow an engineer to certify the use of 20 amp receptacles on a 15 amp circuit.
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#96136 - 11/08/05 04:09 PM Re: 20A receptacles on a 15A circuit.
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
George

 Quote:
My lawnmotor has a 15amp plug and draws 13amps, more than what is allowed on a 15ap circuit.


Can you show me where it is a violation have a 13 amp load on a 15 amp circuit?

 Quote:
But again it is a violation of the NEC unless you hire an engineer and have nhim approve it,


I have no idea why you would think that, almost all jobs I work on are designed by engineers, they still have to comply with the NEC.



[This message has been edited by iwire (edited 11-08-2005).]
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#96137 - 11/08/05 05:27 PM Re: 20A receptacles on a 15A circuit.
Electricmanscott Offline
Member

Registered: 01/12/02
Posts: 1478
Loc: Holden, MA USA
Maybe it takes George over 3 hours to mow his lawn.

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