Two 50 amp receptacles on one 45 amp breaker?

[brother]

I've heard of two 50 amp receptacles on one 45 amp breaker, other than serious design flaw, can we technically say this is a code violation if only one is used at a time? I have heard of people installing 2 30amp dryer recptacles at different locations on one 30 amp breaker. This was because they moved the dryer but never removed the old outlet. Is that technically a code violation? I used to think that these were NEC violations, but now Im not sure.

 

[Little Bill]

I've heard of two 50 amp receptacles on one 45 amp breaker, other than serious design flaw, can we technically say this is a code violation if only one is used at a time? I have heard of people installing 2 30amp dryer recptacles at different locations on one 30 amp breaker. This was because they moved the dryer but never removed the old outlet. Is that technically a code violation? I used to think that these were NEC violations, but now Im not sure.

I see no violation if the intended use is to only use 1 recep at a time.
It's done all the time for welders to make it convieniant to move the welder around without having to have multiple circuits.

 

[ActionDave]

Specific context not withstanding, not a code violation, not a design flaw. I could argue it is good design. No reason to run a bunch of homeruns that are not needed. Better to save those resources for future generations.

 

[kwired]

We do same thing all the time with 15 and 20 amp receptacles, if one of them happens to be intended for a specific heavy enough load then we usually run an individual circuit to it.

With a 50 amp receptacle the load is generally more specific in nature than for 15 and 20 amp circuits, but maybe the application simply is for moving a single piece of equipment from one receptacle location to the another still making it a dedicated circuit, with multiple outlets.

 

[suemarkp]

I think each receptacle is limited to an 80% max load when you have more than one receptacle on a circuit. Most likely your wires are good for 50A, so the breaker may be able to be increased to 50A. That would limit each cord and plug item to a 40A load.

It is the same reason you see "this must be plugged into a 15A dedicated circuit" when you buy a 15A saw with a 15A plug -- the only way to use the full rating of a receptacle is if it is an individual branch circuit.

 

[hurk27]

210.21(B)(3) clearly allows two or more, and refers to table 210.21(B)(3) which allows a 40 amp receptacle on a 40 or 50 amp circuit, sounds like allowed to me.

 

[kwired]

I think each receptacle is limited to an 80% max load when you have more than one receptacle on a circuit. Most likely your wires are good for 50A, so the breaker may be able to be increased to 50A. That would limit each cord and plug item to a 40A load.

It is the same reason you see "this must be plugged into a 15A dedicated circuit" when you buy a 15A saw with a 15A plug -- the only way to use the full rating of a receptacle is if it is an individual branch circuit.

This is true for 15 to 30 amp receptacles, see 210.21(B)(2). It does not say 80% but the values in the table are 80%.

I am not finding anything similar for over 30 amps.

 

[infinity]

210.21(B)(3) clearly allows two or more, and refers to table 210.21(B)(3) which allows a 40 amp receptacle on a 40 or 50 amp circuit, sounds like allowed to me.

More than one 40 amp receptacle on a 50 amp circuit?

 

[jumper]

More than one 40 amp receptacle on a 50 amp circuit?

Don't you have to use 50A receptacles for 40A or 45A circuits? NEMA does not list any 40A receptacles that I know of.

 

[infinity]

Don't you have to use 50A receptacles for 40A or 45A circuits? NEMA does not list any 40A receptacles that I know of.

I think that you're right.

 

[suemarkp]

This is true for 15 to 30 amp receptacles, see 210.21(B)(2). It does not say 80% but the values in the table are 80%.

I am not finding anything similar for over 30 amps.

Right you are -- I just put an 80% rule in my head and didn't remember that it stopped at 30A receptacles.

Only other restriction I see is 210.23(C). If this was in a dwelling unit, you could only plug in fastened-in-place cooking equipment on a 40A or 50A circuit with multiple receptacles. If it is other than a dwelling, looks like you can plug in about what you want.

 

[hurk27]

More than one 40 amp receptacle on a 50 amp circuit?

Don't you have to use 50A receptacles for 40A or 45A circuits? NEMA does not list any 40A receptacles that I know of.

I think that you're right.

Yep got my wire crossed up again, the table allows for a 40 amp circuit a 40 or 50 amp receptacle and for a 45-50 amp circuit it would require a 50 amp receptacle but 210.21(B)(3) and the table is for where two or more receptacles are installed and is why 15 amp receptacles are allowed on a 20 amp circuit in the table, probably what I had my mind wrapped around when I made my post last night.

Guess I was thinking since 15 amp receptacle are allowed on 20 amp circuits when two or more receptacles are installed on it, then this must also be true for 40 amp receptacle on a 50 amp circuit, e'rrr at least my mind thought so :roll:

It is kind of goofy that they switched this around with these two circuit sizes? while most times a 50 amp circuit will be for cooking appliances but there are applications in a dwelling that also use 50 amp circuits like air compressors, hot tubs, saunas, and welders for which we know we can have multiple receptacles, but since NEMA doesn't list a 40 amp receptacle its kind of a mute point.