Electrical question: Edison 5-15 and 5-20 plugs/ receps.

[Telecruiser]

There has been a lot of discusion on this forum about electrical requirements and what is legal/illegal when it comes to inspectors on a job. This got me thinking. A 5-20 edison recep. will accept a 5-15 plug. If you were discovered using a 5-15 plug on a 20 amp breakered 5-20 recep would you be called on it? If this is so why do they allow a 15 amp plug to be used on a 20A recep. from a design standpoint?

 

Andy?

[Miko Man]

I believe that standard 15 amp Edison recepticals are typically wired to 20 amp breaker protected circuits if the in-wall wiring is adequate. It is a convenience to accept the standard lower rated plug in a more robustly constructed circuit, AFAIK. Mark C.

[MrJoshua]

I'm not nearly as knowledgeable about NEC requirements as Andy, but to the best of my knowledge you will not be dinged for using a 5-15 plug in a 5-20 receptacle; they mate for a reason. A 5-20 receptacle should indicate that the wiring to that receptacle and the protection on the circuit are capable of handling a 20A load. You can load UP TO that amount without tripping the breaker. A device or load intended for use on a 15A circuit will work just fine on a 20A circuit since it will be pulling less than 15A. Now once you get outside of the receptacle it is up to you to make sure that you're protected adequately. For example, if you were to plug a 15A-rated power strip into that 20A receptacle you would want to make sure it had its own breaker or fuse to protect it from being overloaded. And this doesn't address multiple receptacles on the same circuit, where your total load is still limited to 20A.

 

This should not be taken as gospel, of course - check the NEC and if still in doubt, talk to a licensed electrician.

[Vinny D]

Every kitchen countertop in the USA *should* have 20a125v outlets on it(wired to current code), never a problem plugging in a toaster.

[agedhorse]

The devil is always in the details...

 

Where a single receptacle (not a duplex) is wired to a 20 amp branch circuit, it must be of the 20 amp (or 15/20 amp) variety.

 

Where a DUPLEX receptacle, or multiple single receptacles are wired to a 20 amp branch circuit, they may be either 15 or 20 amp rated variety.

 

Where the load requires a 20 amp dedicated branch circuit, a 20 amp receptacle (that will match the 20 amp plug) must be used.

 

This pretty much covers the topic, though there are a few unrelated varients.

 

The point of allowing (multiple) 15 amp receptacles on a 20 amp branch is that the receptacle is keyed so that 15 amps is all you will get out of the receptacle from any listed product in the U.S. Multiples are to allow for load diversity of the typical and common applications.