ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat Box
Recent Posts
You will never guess
by andey - 07/13/20 04:08 AM
120/208 gives 240? please clarify
by gfretwell - 07/12/20 03:08 PM
Ceiling Fan Capacitor Question
by libellis - 07/11/20 01:45 PM
Questioning the electrical norms
by gfretwell - 07/09/20 04:35 PM
Blo breaker
by Admin - 07/07/20 02:42 PM
New in the Gallery:
Facebook follies, bad wiring
FPE in Germany pt.2
Who's Online Now
0 registered members (), 14 guests, and 9 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 2 of 3 1 2 3
Re: 15Amp GFCI on 20Amp Circuit? #71971 11/12/06 09:36 AM
Joined: Sep 2006
Posts: 111
Eddy Current Offline
Morning and thanks iwire!

Work Gear for Electricians and the Trades
Re: 15Amp GFCI on 20Amp Circuit? #71972 11/12/06 10:36 AM
Joined: Jan 2005
Posts: 315
luckyshadow Offline
"No offence taken - I should get a copy of the NEC for reference"

Eddy Current -
Try this web site:

There is a copy of the 2005 nec that you can access online. I placed it in my favorites on my computer that way I always access to the code without going out to the truck.

Re: 15Amp GFCI on 20Amp Circuit? #71973 11/12/06 02:01 PM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
UL tests 15 and 20 amp receptacles to the same standards. This is done because the NEC allows 15 amp patterns to be used on 20 amp circuits.

A 20 amp receptacle is tested, assuming a 20 amp circuit. A 30 amp pattern assumes a 30 amp load, etc. So it does matter that you use the right plug pattern for the circuit.

The NEC allows the exception for 15 amp pattern receptacles, because a 20 amp circuit with multiple outlets is, almost by definition, a convenience or general purpose circuit. There is really no way of knowing what loads will be applied, just a near-certainty that they will be numerous, and much less than the rating of the circuit.

The same reasoning cannot apply to a circuit dedicated to a specific appliance. In that circumstance, the circuit - as a whole, and not just the plug pattern- is based upon the specific needs of the appliance.

Re: 15Amp GFCI on 20Amp Circuit? #71974 11/12/06 03:14 PM
Joined: Aug 2001
Posts: 7,520
pauluk Offline
The thing to keep in mind is that a listed 15 amp receptacle is designed and tested to be used on a 20 amp circuit.

I'd bet that there must be at least some makes of 15A receptacles which are manufactured with exactly the same T-slot contact as the 20A version but are just assembled with a different plastic front (with only parallel slots).

Has anyone stripped apart any to confirm this?

Re: 15Amp GFCI on 20Amp Circuit? #71975 11/12/06 03:19 PM
Joined: Jan 2003
Posts: 4,391
iwire Offline
Paul I believe if you where to pull apart the same grade level and brand that the insides are alike.

Bob Badger
Construction & Maintenance Electrician
Re: 15Amp GFCI on 20Amp Circuit? #71976 11/17/06 04:28 PM
Joined: Jul 2005
Posts: 183
jay8 Offline
Personally I dont see why the 20 amp overcurrent is permitted on the 15 amp configuration receptacle. Some homeowner is going to plug their 16 gage extension cord into it, and load it up with who knows what, until it can pull 16 amps continuously and more than that intermittently, with no breaker tripping. Sure your receptacle is rated for the load but who knows what happens downstream.

Re: 15Amp GFCI on 20Amp Circuit? #71977 11/17/06 06:01 PM
Joined: Jan 2003
Posts: 4,391
iwire Offline
Jay how do you see a 20 amp receptacle fixing your concern?

A 20 amp receptacle will accept an extension cord with a 15 amp plug on it.

Bob Badger
Construction & Maintenance Electrician
Re: 15Amp GFCI on 20Amp Circuit? #71978 11/17/06 09:01 PM
Joined: Nov 2002
Posts: 174
kale Offline
Since the nominal 15 or 20amp protection does not protect against using a lamp cord that is not rated for the load it is carrying, that point seems to be moot.

What the 15 amp receptacle configuration does for you is to protect the circuit from connection of a (properly wired) appliance of greater than 15 amps being connected, since the plug doesn't fit. So if you have a circuit wired at 20 amps and limit connection to 15 amps, there shouldn't be a problem.

The T-slot in the 20 amp receptacle allows you to plug in your 1 amp appliance with a 15 amp plug into either receptacle.

Re: 15Amp GFCI on 20Amp Circuit? #71979 11/19/06 09:14 PM
Joined: Sep 2006
Posts: 98
Almost Fried Offline
Pauluk: Specifically yes to your question. If you break apart a residential grade recep.,either 15 or 20 A, you will find the same stampings, they just use a different piece of plastic on the face. And also, the Leviton 5320, pretty much the standard device around here, costs me 39 or 40 cents, the guts are exactly the same as a Decora receptacle, which sells for $ 1.68...
If you open a commercial device, say a hubbell CR15, it has the same innards as a CR 20, just different plastic on the front. Go Figure

On the issue of GFI receps, there seems to be some kind of current sensing built into some that won't allow you to draw more than 15 A from the recep.,I have not done much of a scientifical double blinded by the light test, but several times I have tried to pull more than the 15A load and the unit tripped...

[This message has been edited by Almost Fried (edited 11-19-2006).]

Re: 15Amp GFCI on 20Amp Circuit? #71980 11/23/06 04:01 AM
Joined: Jul 2005
Posts: 183
jay8 Offline
iwire, the 20 amp receptacle should be polarized for 20 plugs and therefore the 15 amp 16 gage extension cord couldnt be plugged into it, so then it wouldnt be carrying the 16 amps or so that the 20 overcurrent would allow. By the way, I am here in Canada, so maybe there is some difference between our 20 amp receptacles and the US version. The use of 20 amp overcurrent on the 15 amp rated cord seems to go back to the screw in fuse days when homeowner, frustrated with the 15 amp fuse always blowing, installs a 30 amp screw in fuse to fix the problem.

Page 2 of 3 1 2 3


2020 National Electrical Code
2020 National Electrical
Code (NEC)

* * * * * * *

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman


Member Spotlight
dallas, texas, USA
Posts: 69
Joined: January 2002
Show All Member Profiles 
Top Posters(30 Days)
Admin 8
Popular Topics(Views)
267,371 Are you busy
202,015 Re: Forum
190,606 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.3