50 amp receptacle

On a 1yr warranty inspection,

The builder added a 240V 50 amp outlet in the garage for the owners ceramic kiln.

The kiln is rated at 30A 240V but has a factory looking 50A cord on it.

The circuit added is 30A 240V using 10ga copper to a 50amp receptacle.

Any exceptions in the code to allow this?

What size was the overcurrent protective device? You can supply a “big” receptacle at less than its rated capacity. The rating of the receptacle is the potential “heavy duty-ness” of the receptacle.

When evaluating large, high-current receptacles, check for:

  • The receptacle has a rating at least as large as the overcurrent protective device (fuse or breaker)*]The branch circuit conductors serving the receptacle have a rating the seems to meet or exceed the sizing required for the fuse or breaker that serves the receptacle.

Problems to look out for:

  • Branch circuit conductors smaller than required for the overcurrent protective device*]Breakers or fuses larger than the rating of the receptacle

A “large” receptacle on a “small” circuit is no problem at all. The breaker will trip if someone, for instance, tries to weld at a full 50 amps with a large welder.

As posted, the circuit is 30 amps. (30 amp breaker)

It seems the same issue as putting a 20 amp receptacle on a 15 amp circuit which is not allowed, right?

Then why is a 50 on a 30 amp circuit ok?


Someone could eventually install a larger breaker for any circuit. There’s nothing peculiar about this circuit that would cause this to happen any quicker than any other circuit.

Marc, please recheck my last post, I was editing while you were posting…

Right… you can always put a “big” receptacle on a “small” circuit if you feel the need. The only time you’re allowed to put a “small” receptacle on a “big” circuit is the special exception that permits 15 amp receptacles on 20 amp circuits.

That does not agree with previous posts about 20 amp recepts on 15 amp circuits.


Is it because the 50 amp receptacle is dedicated or single?

The man asked why a 20 amp receptacle can’t be used on a 15 amp circuit, but nobody (other than the OP) ever suggested that it couldn’t .

see post 6 on that thread

If you want to talk about code, we can do that…

That chart in post 6 of that thread is for circuits with 2 or more receptacles. That chart is taken out of context with respect to this thread.

A single receptacle on an individual branch circuit has to have a rating at least as much as the circuit, and that is the only requirement. You could put a 100 amp receptacle on a 15 amp branch circuit if you wanted to, in the case of a dedicated circuit.

If you have more than one receptacle on the circuit, then and only then, that table you linked to applies.

Thanks Marc!

I would look at the instructions before evaluating this situation.

Here’s a link that may be of some help.

I am curious as to what the instructions have to do with anything.
All I would see is a receptacle and would not care what is plugged in.
Is it wired properly?
Is the circuit sized properly?
Is the overcurrent sized properly?

You are inspecting the house and the wiring. NOT the kiln.
IMO even considering what is being plugged in to a receptacle is far beyond the scope of a home inspection.

See 110.3(B), I want to know what the instructions say about the kiln! I am not inspecting anything, I want to see in black and white what the product instructions say!

Sorry Joe. I know that. The “You are inspecting…” was more hypothetical.

OK, I have discovered electric ranges installed in a basement at the electric dryer location that were supplied with a 30 amp cord. I believe that an inspector has the authority to check for stuff like this. I do it all the time at my seminar hotels.