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#96128 - 11/06/05 10:42 AM 20A receptacles on a 15A circuit.  
cgw  Offline
Member
Joined: Jul 2004
Posts: 133
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.


2017 / 2014 NEC & Related Books and Study Guides

#96129 - 11/06/05 11:07 AM Re: 20A receptacles on a 15A circuit.  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
15 amp circuits that supply multiple receptacles can not feed 20 amp receptacles.


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#96130 - 11/06/05 11:08 AM Re: 20A receptacles on a 15A circuit.  
George Little  Offline
Member
Joined: Jan 2004
Posts: 1,489
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.


George Little

#96131 - 11/06/05 06:11 PM Re: 20A receptacles on a 15A circuit.  
Tesla  Offline
Member
Joined: Jun 2004
Posts: 1,273
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.


Tesla

#96132 - 11/06/05 07:28 PM Re: 20A receptacles on a 15A circuit.  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Quote
While improper, it is almost certainly harmless.


That is not relevant in a forum titled NEC & other Code issues [Linked Image]

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


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#96133 - 11/06/05 09:05 PM Re: 20A receptacles on a 15A circuit.  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
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?


#96134 - 11/08/05 07:13 PM Re: 20A receptacles on a 15A circuit.  
George  Offline
Member
Joined: Feb 2002
Posts: 375
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,


#96135 - 11/08/05 07:54 PM Re: 20A receptacles on a 15A circuit.  
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
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.


Earl

#96136 - 11/08/05 08:09 PM Re: 20A receptacles on a 15A circuit.  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
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).]


Bob Badger
Construction & Maintenance Electrician
Massachusetts

#96137 - 11/08/05 09:27 PM Re: 20A receptacles on a 15A circuit.  
Electricmanscott  Offline
Member
Joined: Jan 2002
Posts: 1,457
Holden, MA USA
Maybe it takes George over 3 hours to mow his lawn.


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