15a GFI on 20a line

Reply

  #1  
Old 09-09-06, 05:45 PM
Member
Thread Starter
Join Date: Apr 2005
Location: USA
Posts: 118
Received 0 Votes on 0 Posts
15a GFI on 20a line

Hi-
12-2NM in garage. 15a GFI protecting 3 20a rated receptacles.
Is this OK? I know the GFI's protection has nothing to do with the 15a rating, just the rating on the receptacle itself.
Thanks. Ray.
 
Sponsored Links
  #2  
Old 09-09-06, 06:00 PM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
This is fine, as far as the GFCI is concerned.

I hope that the NM cable is protected in some way. Many inspectors won't allow NM cable in a garage unless it is either in the ceiling or protected.
 
  #3  
Old 09-09-06, 08:08 PM
Member
Thread Starter
Join Date: Apr 2005
Location: USA
Posts: 118
Received 0 Votes on 0 Posts
Yes racraft-all is inside walls. Thanks once again for your time and knowledge!
Ray.
 
  #4  
Old 09-11-06, 10:06 AM
Member
Join Date: Sep 2000
Location: Fayetteville, NY, USA
Posts: 1,052
Received 1 Vote on 1 Post
The code basically says you can have 15 amp receps on a 20 amp circuit, unless it is a single, dedicated recep, then it must be rated 20A.

But a 20A recep may not be used on a 15 amp circuit.
 
  #5  
Old 09-11-06, 08:09 PM
Member
Join Date: Aug 2005
Location: USA
Posts: 995
Received 0 Votes on 0 Posts
Originally Posted by argekay
12-2NM in garage. 15a GFI protecting 3 20a rated receptacles.
Is this OK?
Is this a 15A GFCI breaker protecting the circuit, or a 15A GFCI receptacle protecting some downstream receptacles, all on a 20A circuit?
 
  #6  
Old 09-12-06, 12:20 AM
Member
Thread Starter
Join Date: Apr 2005
Location: USA
Posts: 118
Received 0 Votes on 0 Posts
Mac702-
Sorry should have been more explicit-
It is a 15a GFCI protecting downstream recepts. The breaker is a standard 20a. All the NM is 12-2.
Thanks to all!
ray
 
  #7  
Old 09-12-06, 12:45 AM
Member
Thread Starter
Join Date: Apr 2005
Location: USA
Posts: 118
Received 0 Votes on 0 Posts
Receptacle rating revisited

I don't understand the logic of allowing a 15a rated recep on a 20a line. My logic (probably faulty) says that any OCPD protects downstream components (i.e. wiring and receps). To me it seems as though this is purely a thermal issue (plastic jacketing around wires and wood next to NM cable will burn before the actual copper wire). If this is so, why does the code allow a 15a rated recep on a 20a line? As an example, even in a multiple recep NM run, if I only happen to be using one of those receps, and the load on that recep is 19a (not enough to trip the breaker), would not that recep exceed it's thermal rating (and get overheated) before the thermal rating on the NM cable is exceeded? Lets take the reverse- I have a 15a breaker with 14-2 NM. Why can I not have a 20a rated recep on that line? If I draw a 17a load on that circuit, it seems to me that the OCPD will trip and protect the lowest capacity component (the 14-2 NM) will be properly protected. The recep in this case does not overheat. The only problem I can see is placing an inapropriate OCPD (i.e. 20a breaker on a 14-2 line) in a circuit.
Hope I didn't open up a can of worms!
Ray.
 
  #8  
Old 09-12-06, 12:53 AM
Member
Join Date: Aug 2005
Location: USA
Posts: 995
Received 0 Votes on 0 Posts
15A and 20A receptacles are basically identical in construction. It's just the pin configuration that sets them apart.

All the ones I know of will pass 20A with no problems, especially the GFCI receptacles.
 
  #9  
Old 09-12-06, 12:57 AM
Member
Join Date: Aug 2005
Location: USA
Posts: 995
Received 0 Votes on 0 Posts
Originally Posted by argekay
Why can I not have a 20a rated recep on that [15A] line?
Because then one should be able to assume that a 20A load is okay, when they see a 20A receptacle.
 
  #10  
Old 09-12-06, 01:40 AM
Member
Thread Starter
Join Date: Apr 2005
Location: USA
Posts: 118
Received 0 Votes on 0 Posts
thanks mac702!
 
  #11  
Old 09-12-06, 10:05 AM
Member
Join Date: Sep 2000
Location: Fayetteville, NY, USA
Posts: 1,052
Received 1 Vote on 1 Post
With a 20 amp breaker and 12-2 NM cable, you are certainly permitted to replace any and all 15A receps with 20A rated receps. Just not required. It is very common to have all 15A receps on a 20 amp general purpose lighting and receptacle circuit. The 20A models are a bit more expensive, and few homeowners have corded appliances and tools that draw over 15 amps. Exceptions would be, say, a window air conditioner, or a commercial power tool. (I had a 1 HP table saw once. Draws 16 amps and had a 20A plug. Had to upgrade a circuit just so I could use it.)
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: