15A GFCI on 20A Circuit


  #1  
Old 01-29-04, 08:19 PM
Nucleus
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15A GFCI on 20A Circuit

Running a 20A circuit in a garage. Of course, breaker is 20A, wire is 12, receptacles are 20A.

What is not 20A is the first outlet which is a 15A GFCI. Reason...I had 15A sitting around. So, is it o.k. (legal) to run for protection a 15A GFCI on an otherwise 20A circuit?

Thanks.
 
  #2  
Old 01-29-04, 09:08 PM
bungalow jeff
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Except when there is a single outlet is on a 20Amp circuit, all reveptacles can be 15Amps.
 
  #3  
Old 01-29-04, 09:08 PM
cajon ken
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I started this reply with yes I thought it would be OK to put that 15A GFCI receptical in the circuit but have now talked myself out of it. The rating of the recepticle has to do with the size and thickness of the parts that make it up. The GFCI (ground fault circuit interruptor) trips not when there is too much current but when there is an imbalance of current (like when you touch the hot lead or whatever appliance that is pluged into it gets a short. So following that logic if an appliance on this circuit was drawing 20A it could certainly burn out the GFCI. Keep the 15's with the 15's and keep the 20's with the 20's. You'll not go wrong.
 
  #4  
Old 01-29-04, 10:12 PM
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cajon ken,

This logic is incorrect. The only thing about a 15 amp GFI that is 15 amp is the receptacle configuration. It is still a 20 amp feed through device. Look at ANY GFI, and see what it says.

You cannot "burn out" a GFI by overloading it. As long as the circuit is sized properly the breaker will trip long before you hurt a GFI.
Also GFI's don't short, they trip, due to the imbalance you mentioned.

There absolutely is no reason at all to use 20 amp devices in a residential installation. Except, maybe in a garage where there is the possibility of needing the 20 amp configuration for a heavy load like a compressor, or in the house for an A/C.
210.21(B)(3) is very clear on this.

I'm sorry but this is a case of knowing a little is worse than knowing nothing.
 
  #5  
Old 01-30-04, 05:54 AM
Nucleus
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Originally posted by bungalow jeff
Except when there is a single outlet is on a 20Amp circuit, all reveptacles can be 15Amps.
I'm not sure what you mean?
 
  #6  
Old 01-30-04, 05:57 AM
Nucleus
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Originally posted by Speedy Petey
The only thing about a 15 amp GFI that is 15 amp is the receptacle configuration. It is still a 20 amp feed through device. Look at ANY GFI, and see what it says.

There absolutely is no reason at all to use 20 amp devices in a residential installation. Except, maybe in a garage where there is the possibility of needing the 20 amp configuration for a heavy load like a compressor.
Well, the circuit is for the garage so I do need a 20A.
Also, yes, the GFCI does say 20A on the side of it, but 15A on the mounting tabs. So, does this mean it's o.k. to use in my setup?

Thanks for the replies.
 
  #7  
Old 01-30-04, 06:28 AM
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To repeat: the only thing that "15A" means on a receptacle is that it will accept a 15A plug and not a 20A plug. A "20A" receptacle will accept either a 15A or a 20A plug. .
Well, the circuit is for the garage so I do need a 20A.
What do you need to plug in that has a 20A plug? As Speedy Petey said, there are almost no residential applications that use a 20A plug (outside of large A/C units). Even if you needed a 20A plug in the garage, it is perfectly safe to put a 20A receptacle downstream of (and protected by) the 15A GFCI.
 
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Old 01-30-04, 06:35 AM
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You may use the GFCI in your garage.

The GFCI itself will only accept a 15 amp style plug, but the GFCI device itself is rated for 20 amps and will provide feed through protection for the full 20 amps.

Just to clarify.

A 20 amp circuit does not mean 20 amp plugs. A 20 amp circuit means a 20 amp breaker and 12 gauge wire. As long as you have more than one outlet on the circuit (and a duplex outlet qualifies as more than one outlet), you are not required to have 20 amp outlets, you can have 15 amp outlets. It is only if the 20 amp circuit terminates at a single outlet (not a duplex outlet) that you are required to have a 20 amp outlet. (Note: I am not talking about switches or receptacles to keep the discussion simple.)

Single 110 volt 20 amp outlets in residences are very rare. You may find one for a window air conditioner, or other current hungry appliance, but even that is rare.

For your setup, all of your outlets in the garage may be 15 amp outlets, or they may be 20 amp outlets, or they may be a combination of the two.
 
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Old 01-30-04, 07:04 AM
Nucleus
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Thanks for the help
 
  #10  
Old 01-30-04, 08:03 AM
bitpicker1011
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I have exactly the same issue and you guys have answered it thoroughly. Thanks! But I do have one question.

What is the logic or electrical theory that makes a 20A outlet required if it is the only outlet on the 20A circuit but not if there are more outlets? I'm not asking where in the code just why is that the code.
 
  #11  
Old 01-30-04, 09:09 AM
hotarc
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Originally posted by racraft


..... It is only if the 20 amp circuit terminates at a single outlet (not a duplex outlet) that you are required to have a 20 amp outlet. (Note: I am not talking about switches or receptacles to keep the discussion simple.)

Single 110 volt 20 amp outlets in residences are very rare. .........

Racraft, with all due respect, I believe you are actually talking about receptacles. In the code's eyes, an outlet can be either a lighting outlet or a receptacle outlet. The term "outlet" by itself is not exclusive to receptacles.
 
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Old 01-30-04, 09:20 AM
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hotarc,

I used the term outlet because the topic is about outlets in a garage. When adding to discussions on this board I prefer to keep the responses simple. Distinguishing between outlets and receptacles confuses many people.

Although the original poster did use the term receptacle, he also used the term outlet.

Most people consider an outlet to be the devices, usually on the wall, that you plug something (such as a drill or a toaster) in to.
 
  #13  
Old 01-30-04, 09:28 AM
hotarc
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Originally posted by racraft
.......
Most people consider an outlet to be the devices, usually on the wall, that you plug something (such as a drill or a toaster) in to.

Yeah, I know. I guess I just thought I'd interject for the sake of using proper terminology. Sometimes I forget this is a DIY forum where the question posters aren't necessarily familiar with the code and all of its various terms.
 
  #14  
Old 01-30-04, 10:19 PM
bungalow jeff
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Jeepers, I thought I answered it in lay terms. The answer to every question should be appended with "please pick up a basic electrical book".
 
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Old 01-31-04, 04:46 AM
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Jeff, that's not the worst idea.

Some people should realize they need some electrical knowlege before attempting electrical work.
Not: "What wire do I need for a 220 plug?"
 
  #16  
Old 02-02-04, 06:51 AM
Nucleus
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Originally posted by bitpicker1011
What is the logic or electrical theory that makes a 20A outlet required if it is the only outlet on the 20A circuit but not if there are more outlets? I'm not asking where in the code just why is that the code.
I'm curious too...anyone?
 
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Old 02-02-04, 04:43 PM
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Single receptacle outlet to match circuit.

The logic here is that in order to use the entire ampacity of the circuit you must be able to plug in a twenty ampere load. If the circuit were terminated to a single fifteen ampere receptacle then the occupants would need to use multi-taps to use the ampacity of the circuit. If you look on the commercially available portable power taps you will see that they are breakered or fused at fifteen amps if they have a fifteen ampere plug. Only a tap that is equipped with a twenty ampere fuse or breaker will have a twenty ampere plug on it's attachment cord.
--
Tom
 
 

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