15 amp receptacle on 20 amp circuit?

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Old 05-30-10, 02:28 PM
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15 amp receptacle on 20 amp circuit?

I've read on other forums two opinions about whether 15 amp receptacles can be installed on 20 amp circuits. Some say yes and point to NEC code that says it's allowed; others say it's against code and that people are "reading into" the code. I don't have a codebook. Can someone give me a definitive answer? If 15 amp receptacles are allowed on 20 amp circuits, are there pros and cons for installing one or the other?

I'm planning for receptacles on a 20 amp circuit in a detached garage, as well as for dedicated outlets for refrigerator and dishwasher in a kitchen.
 
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Old 05-30-10, 03:57 PM
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Yes, they are allowed by NEC as long as there is more than one place to plug an appliance in (meaning one duplex receptacle). If it's a single receptacle (not a duplex) on a 20 amp dedicated circuit, the single receptacle must be rated at 20 amps. Your garage receptacles must be GFI protected. A 15 amp GFI receptacle has a feed through rating of 20 amps just for the application of being on a 20 amp circuit (as above).
 
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Old 05-30-10, 06:36 PM
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Nicely summed up Joe. .
 
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Old 05-30-10, 08:20 PM
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Thanks, CasualJoe.

I'm assuming the same applies for the receptacles on the two 20-amp small appliance countertop circuits in a kitchen (and the GFCI receptacle at the beginning of those two runs)? Is this correct--those can all be 15 amp? There aren't exceptions for any particular location?
 
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Old 05-30-10, 11:37 PM
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In the Kitchen area they have to be 20 amp circuit and it must have 4.0mm˛ {#12 AWG } conductor or cable but for the receptale it can be duplex as Joe did explain real clear on it and that is correct for USA side however in Canada no it is not correct it must have T-slotted recpetale on 20 amp circuits { that is Canada Electrical code }

For any exceptions no there is none in USA kitchen circuit you can use 15A duplex recetpales that not a issue with 20 amp circuits however if singleplex no that have to be 20 amp singleplex receptale { it little more harder to find it but many big box store do stock it anyway }

Just make sure watch the spacing on the kitchen receptales.

For garage receptale it MUST be on GFCI { either GFCI breaker or GFCI receptale { at the first recepatle on the circuit }
Oh yeah the extempts are gone if you are on 2008 NEC code cycle unless there is specfic local requirement they will let you know { check the city or county electical inspectors they will fill you in if they have specfic requirement}

Merci,Marc
 

Last edited by stickshift; 07-10-14 at 01:59 PM. Reason: Removed quoting of entire post
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Old 06-01-10, 09:20 AM
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Originally Posted by nugentcn View Post
are there pros and cons for installing one or the other?
I don't think I've ever seen a residential-grade kitchen appliance that uses a true 20A plug. Buying t-slot 20A receptacles is a waste of money. Manufacturers simply do not design appliances that could only be used in the small percentage of homes with 20A receptacles.

It might make sense to install one T-slot the garage in case you ever wanted to use a little buzz box welder or moderate sized air compressor. Even then they usually have 15A plugs.
 
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Old 06-07-10, 08:11 AM
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I've got a similar question on the same mindset. I'm running a 20A circuit in my bathroom in my basement. Now the bathfan I bought is obviously using 14 g wires. Is is ok to wire the 12-3 into the 14-3 at the fan? I've already run the 12-3 to it but in hindsight could I have used a 14-3? Thanks.
 
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Old 06-07-10, 08:22 AM
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Are you asking about the internal wiring of the fan?
 
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Old 06-07-10, 01:10 PM
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Yes, the fan has 14 gauge wires that is part of the fan but I'm wiring it on a 20A circuit using 12 gauge wire.
 
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Old 06-07-10, 02:28 PM
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You will be fine using the #12 house wires connected to the wires supplied with the fixture.
 
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Old 06-07-10, 03:52 PM
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MNJay, if the wires in the fan are 14 gauge, doesn't the breaker need to be 15 amp rather than 20? My understanding is that oversized wiring is okay, but undersized is not safe.
 
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Old 06-07-10, 03:58 PM
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Originally Posted by nugentcn View Post
MNJay, if the wires in the fan are 14 gauge, doesn't the breaker need to be 15 amp rather than 20? My understanding is that oversized wiring is okay, but undersized is not safe.
Comparing apples and oranges. Fixture wiring often has higher temperature ratings and can therefore can handle more amps. Also breakers and fuses are there to protect the house wiring not the fixture or the fixture's wiring. Go look at a table lamp as an example. The cord is probably only #18.
 
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Old 06-07-10, 04:02 PM
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Originally Posted by nugentcn View Post
MNJay, if the wires in the fan are 14 gauge, doesn't the breaker need to be 15 amp rather than 20? My understanding is that oversized wiring is okay, but undersized is not safe.
You must think about it a little. He's running a 20 amp circuit to the bathroom that will supply a receptable or receptables and a fan/light combo. The total draw could be more than that 15 amp circuit plus a bathroom must be supplied by at least 1 20 amp circuit. Now if he just wanted to run another circuit just for the fan then a 15amp- 14 gauge would be OK but still needs that 20 circuit for the receptables. Ray2047 also has a good point.

Jim
Beer 4U2
 
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Old 06-07-10, 08:21 PM
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The load the fan will draw is known and is accounted for even with the smaller wires. Loads on a branch circuit for a receptacle is an unknown and the wire needs to be sized to the breaker.
 

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Old 06-08-10, 07:07 AM
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Thanks guys, appreciate it.
 
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Old 06-17-10, 12:54 PM
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Originally Posted by ibpooks View Post
I don't think I've ever seen a residential-grade kitchen appliance that uses a true 20A plug. Buying t-slot 20A receptacles is a waste of money. Manufacturers simply do not design appliances that could only be used in the small percentage of homes with 20A receptacles.

It might make sense to install one T-slot the garage in case you ever wanted to use a little buzz box welder or moderate sized air compressor. Even then they usually have 15A plugs.
The 20A requirement in the kitchen was done more for the fact of having the circuits be capable of running multiple small appliances than being capable of running a large 20A appliance. For example, your average Joe wouldn't think twice about plugging their 6A coffee pot and 12A waffle iron into the same receptacle. It was to keep that person from having to run downstairs every time they forgot and tripped the 15A breaker.
 
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Old 06-25-10, 02:39 PM
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Originally Posted by CasualJoe View Post
If it's a single receptacle (not a duplex) on a 20 amp dedicated circuit, the single receptacle must be rated at 20 amps.
What is the thinking behind this? Why would the number of receptacles matter?
 
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Old 06-25-10, 02:45 PM
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The idea is that a circuit with only one receptacle is generally intended to be used with one large appliance, whereas a circuit with many receptacles is intended to be used with a couple smaller appliances.

Also I'm sure it has something to do with 15A receptacles being cheaper and >99% of household appliances having 15A plugs.
 
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Old 06-25-10, 02:48 PM
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Originally Posted by JerseyMatt View Post
The 20A requirement in the kitchen
I was only talking about the 20A T-slot recepts, not the 20A circuit itself. Nothing resi-grade has an actual 5-20 plug, they're all 5-15.
 
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Old 06-25-10, 04:48 PM
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Quote:
Originally Posted by CasualJoe
If it's a single receptacle (not a duplex) on a 20 amp dedicated circuit, the single receptacle must be rated at 20 amps.

Originally Posted by ii_diesel_ii View Post
What is the thinking behind this? Why would the number of receptacles matter?
If you have a 20 amp dedicated circuit with a single 15 amp receptacle, you could never utilize the full capacity of the circuit without exceeding the capacity of the receptacle.
 
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Old 06-25-10, 08:08 PM
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Really?? Can you explain the physical difference if any, between a 5-15 and a 5-20, other than the prong configuration? The correct answer would be ABSOLUTELY NOTHING BESIDES THE CONFIGURATION. While code generally calls for a 20 amp configuration for a SINGLE receptacle of a 20 amp configuration on a 20 amp circuit, and allows a 15 amp receptacle for a single duplex receptacle, most localities i have ever worked in require 20 amp devices on a 20 amp circuit. You would do well to take this up with your inspecting authority.
 

Last edited by stickshift; 07-10-14 at 02:02 PM. Reason: Removed quoting of entire post
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Old 06-26-10, 03:51 PM
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Can you explain the physical difference if any, between a 5-15 and a 5-20, other than the prong configuration? The correct answer would be ABSOLUTELY NOTHING BESIDES THE CONFIGURATION.
In my opinion, any physical differences or lack therof are not the issue, the U.L. listed rating of the device is what matters. Exceeding 15 amps on a 15 amp rated device violates the U.L. listing of the device and would be a code violation.

You would do well to take this up with your inspecting authority.
Taking this up with the AHJ is not necessary as long as the AHJ follows the NEC.
 
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