ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Increasing demand factors in residential
by gfretwell - 03/28/24 12:43 AM
Portable generator question
by Steve Miller - 03/19/24 08:50 PM
Do we need grounding?
by NORCAL - 03/19/24 05:11 PM
240V only in a home and NEC?
by dsk - 03/19/24 06:33 AM
Cordless Tools: The Obvious Question
by renosteinke - 03/14/24 08:05 PM
New in the Gallery:
This is a new one
This is a new one
by timmp, September 24
Few pics I found
Few pics I found
by timmp, August 15
Who's Online Now
1 members (Scott35), 274 guests, and 15 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 3 1 2 3
Joined: Jul 2004
Posts: 136
C
cgw Offline OP
Member
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.

Stay up to Code with the Latest NEC:


>> 2023 NEC & Related Reference & Exam Prep
2023 NEC & Related Reference & Study Guides

Pass Your Exam the FIRST TIME with the Latest NEC & Exam Prep

>> 2020 NEC & Related Reference & Study Guides
 

Joined: Jan 2003
Posts: 4,391
I
Moderator
15 amp circuits that supply multiple receptacles can not feed 20 amp receptacles.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Joined: Jan 2004
Posts: 1,507
G
Member
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
Joined: Jun 2004
Posts: 1,273
T
Member
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
Joined: Jan 2003
Posts: 4,391
I
Moderator
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
Joined: Jan 2005
Posts: 5,445
Likes: 2
Cat Servant
Member
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?

Joined: Feb 2002
Posts: 375
G
Member
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,

Joined: Dec 2003
Posts: 751
E
Member
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
Joined: Jan 2003
Posts: 4,391
I
Moderator
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
Joined: Jan 2002
Posts: 1,457
E
Member
Maybe it takes George over 3 hours to mow his lawn.

Page 1 of 3 1 2 3

Link Copied to Clipboard
Powered by UBB.threads™ PHP Forum Software 7.7.5