Okay, we've all know that a 15amp recept. will work fine on a 20amp circuit, but what about GFCIs?

I overheard an argument at the big Orange Box tonight while getting some light sockets for a traffic signal. The "Expert" and an electrician were in a heated argument about using 15amp GFCIs on 20amp circuits. The HD Guys said you could, the electrician said you can't. Which one is it? Something tells me 15amp GFCIs shouldn't be used on 20amp circuits though...

Ian A.

Read the instructions, most* are rate for 20A feed through.


* BTW, never have seen one that was not.

In Canada when the new code came out about using 20a GFI's beside the sink, I used a 15 amp GFI on a 12awg-20amp circuit and got a defect from the inspector. I noticed "20amp" is printed on the side of a 15 amp GFI(Leviton) so I thought I could use it.

This is the only code I can find right now.

CEC 14-600 Receptacles shall not be connected to a branch circuit having overcurrent protection rated or set at more than the ampere rating of the receptacle except as permitted by other Sections of this Code.

Found another code CEC 26-712(d) where it refers to kithen receptacles it states either "15amp SPLIT or 20amp T-slot" receptacles.
So until they make a 15amp GFI that you can split - in Canada - I say no!

The new T-Slot GFCI Receptacles are rated for 15amp and 20amp.

My understanding is that although the 15amp GFCI is Rated for 20amp, the configuration is meant for 15amp only. However, the T-Slot is rated and will take a 15 or 20 amp cord.

T-slots can be used for 15 or 20amp appliances- they are not rated for 15 or 20 amp.
What I'm saying is you can't use the t-slot on a 15 amp circuit and you can't use a 15amp GFI on a 20amp circuit.

No offense meant to our Canadian friends but can we use the NEC here.

A GFCI receptacle is above all else still a UL listed receptacle.

Both the NEC and UL expects and allows 15 amp duplex receptacles on 20 amp circuits.

If a 15 amp rated receptacle has a UL listing it will be listed for use on 20 amp circuits.

No offence taken - I should get a copy of the NEC for reference.
I find it odd that the NEC allows this? Can you use a 20amp receptacle on a 30a circuit, or a 30a receptacle on a 40a circuit? Or is there a code just for the t-slot GFI's.
Can you use regular 15amp receptacles on a 20amp circuit? Can you use t-slots on a 15amp circuit?

Good morning Eddy.

I agree at the outset it sounds odd.

The NEC allows multiple 15 amp receptacles on 15 or 20 amp branch circuits.

If it is a circuit with just a single receptacle than you would need a 20 amp receptacle on a 20 amp circuit.

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.

Are all 15A GFCI receptacles designed and listed to serve 20A on the load terminals, or must we be careful when buying?

Morning and thanks iwire!

"No offence taken - I should get a copy of the NEC for reference"

Eddy Current -
Try this web site: www.nfpa.org/freecodes/free_access_agreement.asp?

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.

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.

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?

Paul I believe if you where to pull apart the same grade level and brand that the insides are alike.

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.

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.

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.

TheKid:
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.

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).]

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.

Jay,
[quote]the 20 amp receptacle should be polarized for 20 plugs and therefore the 15 amp 16 gage extension cord couldnt be plugged into it, ... [quote]
15 amp cord caps will fit in 20 amp receptacles...20 amp caps won't fit in 15 amp receptacles. At least that is how it is in the US.
Don

Thanks Don.

Jay here are the configurations we use in the US, I don't know if they match Canada.








As you can see the 20 amp receptacle is intended to accept both 15 and 20 amp plugs.

In reality there are almost no home appliances that come with a 20 amp plug on them.



Virtually all 125 volt home appliances have 15 amp plugs.



Bob


[This message has been edited by iwire (edited 11-23-2006).]

Jay a 20 amp breaker will allow 20 amps for at least 3 hours and likely forever.

It may even allow 24 amps forever.

The standard modeled case breakers we use for branch circuits are hardly precise devices and much depends on the ambient temperature where the breaker is located.

If your interested, look at some trip curves for breakers, they can be found at the web sites of the manufacturers.

[This message has been edited by iwire (edited 11-23-2006).]

i dont want to drag this out forever, but my point was simply that 16/20/24/2000 amps it doesnt matter, if code is allowing cheapo 16 gage extension cords on the 20 amp overcurrent, I see a potential hazard - or am I out to lunch here?

Am I wrong in the opinion that the NEC and CEC are based on protecting the wires in the wall and the devices attached to those wires? Not necessarily the devices plugged into or attached to the circuit.

I am not sure about the NEC, but the CEC bases the maximum loading of circuit breakers at 80% of Maximum Capacity (or the manufacturers base loading at 80% continuous draw). Here in Canada, we are not allowed to put a NEMA 5-15R rated for 15amps on a 20amp circuit. It doesn't matter that the receptacle is rated for 20amp, it is classed as a 15amp device and is therefore required to be on a maximum 15amp circuit.

Further, we are not allowed to install the NEMA 5-20R on a 15amp circuit... the circuit and breaker must be wired to allow for the maximum ampacity of 20amp. However, there is no restriction to plugging a 15amp device into the 20amp T-slot device, as it is designed to accept both 15 and 20 amp devices.

Is this not correct?



[This message has been edited by ExpressQuote (edited 11-23-2006).]

If you have something like 240.4(D) (15a on 14ga copper, 20a on 12ga) you already have the 80% built into the overcurrent protection. The NFPA understands they have no control what a user will plug in. Even if you limited each receptacle to 15a configuration, that doesn't keep someone from plugging two 1440 watt heaters into receptacles on the same circuit. They set the overcurrent protection artifically low for "small conductors". 310.15 says a 14 copper is good for 20a and a 12 good for 25a, at 60c. There is your 80%.