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15 / 20 amp question

G

GrimBeeper

Registered User
Joined
Feb 16, 2017
Messages
28
Location
Portland, OR
I'm converting a basement room to be an office, and the basement is already wired with 12awg cable and 20 amp breakers. I want to use some outlets that have USB adaptors, but these are only available in 15amp. My questions are:

1. Can I (in Portland Oregon) put a series of 15amp receptacles on a 12awg 20 amp circuit?
2. If yes, is this wise? It will be used for things like laptops, monitors, hard drives etc.
3. I don't see residential applications wired with 20amp receptacles - is there any reason not to use 20amp receptacles for residential?
Thanks!
 
Technically you are probably voiding the listing of the Receptacle....But It will likely never be a problem in the real world...Swap in a 15A breaker would make it compliant.
 
Thanks Steve - so you think it won't pass inspection? I can't just swap a breaker, there is other stuff on the circuit - I'd have to run a new breaker and new circuit, which I don't want to do because I would have to disturb finished work. I have the 20amp circuit conveniently available, so would prefer to use it. I guess what I want to know is a) do I have to run all 20amp receptacles, or b) can I use 15amp receptacles. I'm thinking it wouldn't be a problem, since it will only have the effect of reducing the theoretical maximum draw on the circuit.
 
Welcome

1) Can't speak for Portland in particular, but for your application, yes, the unamended 2014 NEC allows multiple 15 or 20 amp receptacle outlets on a 20 ampere circuit. Table 210.21(B)(3)
2) Should be safe, equipment your using would probably fry on either 15 or 20 amps.
3)See it sometimes, hard to say why it was done that way, could be as simple as they had an excess of 12 ga wire. Maybe they were planning a music studio.....

Not an electrician......
 
It is very common, and allowed by Code, to install 15 or 20 amp duplex receptacles on a 20 amp branch circuit. Only need a 20 amp receptacle if it is a single receptacle. 2014 NEC 210.21 (B) (1) and Table 210.21 (B) (2) and 210.21 (3)
 
210-21(b)(3) Receptacle Ratings

Where connected to a branch circuit supplying two or more receptacles (or outlets), receptacle ratings must correspond with the values listed in Table 210-21(b)(3). Specific receptacle ratings are stipulated for branch circuits that are rated 15, 20, 30, 40, and 50 amperes. A 15-ampere branch circuit can supply 15-ampere receptacles, but not 20-ampere receptacles. A 20-ampere circuit can supply either 15- or 20-ampere receptacles.

In short 15 or 20 amp receptacles can be used on a 20 amp circuit.
Only 15 amp can be used on a 15 amp circuit.
 
Check the receptacle on the refrigerator circuit, good chance that the breaker is 20-Amp and the Wire is 12/2wg and the receptacle's probably a 15-amp depending on the code year that was used when your home was built. Current codes have GFCI's and AFCI's everywhere now.

In a work shop set-up I like a 20-amp, receptacle, 20-amp breaker with 12/2wg wire because some power tools have a slight power spike when turn on. I once had a radial-arm saw that was on a garage GFCI that tripped all the time.:mad:
 
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The breaker and the wire gauge determine maximum capacity of the circuit.
Just don't plug a high draw appliance in to an underrated outlet...
 
Pcinspector, I once had a radial saw on a 12 ga. 20 amp circuit, but I changed the breaker to 15 amps so it would trip before the thermal overload (which took forever to cool down) when the saw would bind.
 
GrimBeeper said:
I'm converting a basement room to be an office, and the basement is already wired with 12awg cable and 20 amp breakers. I want to use some outlets that have USB adaptors, but these are only available in 15amp. My questions are:

1. Can I (in Portland Oregon) put a series of 15amp receptacles on a 12awg 20 amp circuit?
2. If yes, is this wise? It will be used for things like laptops, monitors, hard drives etc.
3. I don't see residential applications wired with 20amp receptacles - is there any reason not to use 20amp receptacles for residential?
Thanks!
Click to expand...
The reason the code allows you to use 15 amp receptacles on a 20 amp circuit is because a 20 a 120 volt appliance has a special plug , one prong is at right angles to the other . So the 20 amp plug wont go into the 15 amp recept . , but the 20 amp recept has an extra slot so 20 or 15 amp plugs can be used .
 
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