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20amp circuit with a 15amp plug?!

post #1 of 4
Thread Starter 
Hey, AVS..

Just noticed that Electrician wired my Equipment closet with 15amp receptacles (NEMA 5-15) on a 20 amp circuit.

This has been "done" for a while now, and I just noticed shopping for rack-mount Power Distribution Units (PDUs). Since I have 20 amp circuits, I was shopping for 20 amp PDUs. But then I noticed they all use NEMA 5-20 plugs, where one of the slots is turned sideways.


- Did the Electrician screw up/try to short us somehow?

- Is this even "to code"? I read somewhere else that 15A receptacles are supposed to support "20A passthrough".

- If I put a 15 amp PDU in the rack, will I get any benefit from the 20 amp circuit? Or, should I make him come back out (yeah, right) and change the plugs?

Not sure what it means to us overall having a 15A plug on a 20A circuit. Can you guys help fill in a complete electrical noob?


- B
post #2 of 4
I would replace the receptacle with a 20 amp one and use the 20 amp PDU, or go with a 15 amp unit.

I think you would be surprised how easy it is to replace the outlet yourself. Even for the first time, it's probably less than a 1/2 hour job. The receptacle will cost you <$5.

Start out by getting one of those little circuit checkers from a hardware store to verify that your outlet is wired correctly (ground wired, and hot/neutral on the correct sides)

Find the circuit breaker, flip it off. Verify the circuit is off(!) Unscrew the cover plate and then the receptacle.

Pull the receptacle out of the junction box. The wires should unfold a bit. Transfer the wires from the old receptacle to the new one. If your socket was wired correctly (as checked above) just keep them in the same relative locations on the new socket.

I'm not sure on this but I think on a 20amp outlet you need to use the screw attachments and can't use the push-in connectors on the back of the receptacle. I'm not sure, because I always use the screw in kind anyway.

Put the receptacle back into the box. Getting all the wires to fold back in is often the hardest part. Screw the receptacle to the box and screw the cover back on. Good to go.
post #3 of 4
Just to let you know...it is fine to put 15amp outlets on a 20amp circuit. The opposite is what's not allowed.....you can't put 20amp outlets on a 15amp circuit.

I did that exact thing in my theater, it just allows you to install a few extra outlets without overloading the circuit. You just have to make sure you install 12guage(yellow) romex instead of the 14guage white wire.
post #4 of 4
A 15 amp receptical can still supply 20 amps. AT least the metal on the screw section has to support 20a as this is a loop through. So they aren't going to use a different piece of metal for the contacts, it's just one piece - cost of manufacturing.

The reason for true 20 recepticals is for equipment that is over 15 amps of current draw. They are supposed to have a 20a 120v plug so they can't be plugged into a 15a receptical. While a 15a circuit would stil trip with the overload, the NEC sought to make it a non issue in the first place.

Like always the hacks of the world will not be incovienenced. They often just twist the horizontal prong of the 20a plug vertical so it fits in a 15a outlet.

Yes do replace the receptical. It a small cost to do it right.
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