Why can 't you put a 15A single receptacle on a 20A circuit?

[Sir String]

I understand that according to sec 210.21(B)(1), a single receptacle on a 20A breaker has to be 20A.

But according to sec 210.21(b)(3), if I have more than one 15A receptacle on a 20A breaker, it's ok.

What's the purpose of the rule? I can't see how a duplex 15A receptacle on a 20A circuit is safe, but a single isn't.

 

[OregonSE]

The use of multiple 15 amp receptacles on a 20 amp circuit is permitted. A duplex receptacle is considered as multiple receptacles and is therefore permissible to use as the single, or one of several, multiple type receptacles on the circuit.

Part of the UL listing for the 15 amp receptacles is that they are capable of feeding through the 20 amp circuit, the primary difference between 15 and 20 amp receptacles being the faceplate configuration.

Receptacles rated higher than the circuit rating may not be used, so 20 amp receptacles are not permitted on a 15 amp circuit.

 

[480sparky]

I think the reasoning is that if you have a single circuit supplying a single receptacle, the load is known.

Otherwise, it becomes a 'general-purpose' circuit.

 

[Dennis Alwon]

It is an oddity because if you had a piece of equipment that used more than 15 amps I would presume it would have a 20 amp male end.

 

[Jim W in Tampa]

Why would you need to have a 20 amp breaker if only feeding one 15 amp receptacle ? Either replace breaker with 15 or receptacle with 20
I do agree that there is no hazard to justify the rule but its NEC and does not need to have logic

 

[Sir String]

Why would you need to have a 20 amp breaker if only feeding one 15 amp receptacle ? ...

Agreed. It's easy enough to comply, I was just wondering about the logic behind it.

 

[tryinghard]

In dwelling units some may choose to use 15A duplex on the small appliance 20A circuits.

 

[kbsparky]

....Receptacles rated higher than the circuit rating may not be used, so 20 amp receptacles are not permitted on a 15 amp circuit.

And yet, 50 amp receptacles (range outlets) are routinely used on 40 Amp circuits!

So what is the difference? Those receptacles are rated higher than the circuit rating.

 

[infinity]

T.

Receptacles rated higher than the circuit rating may not be used, so 20 amp receptacles are not permitted on a 15 amp circuit.

Just to clarify 20 amp receptacles are not permitted on a 15 amp circuit but a 20 amp single receptacle is permitted.

 

[Jim W in Tampa]

Agreed. It's easy enough to comply, I was just wondering about the logic behind it.

This is NEC they don't need LOGIC or FACTS

 

[Sir String]

Just to clarify 20 amp receptacles are not permitted on a 15 amp circuit but a 20 amp single receptacle is permitted.

I don't think so. Did you mean to say 15 amp receptacles are permitted on a 20 amp circuit but a 15 amp single receptacle is not permitted?

 

[cpal]

a 20 single is permitte on a 15 A BC. If you over load the 15 A ckt the OCPD will trip.

 

[Dennis Alwon]

I don't think so. Did you mean to say 15 amp receptacles are permitted on a 20 amp circuit but a 15 amp single receptacle is not permitted?

Trevor is saying that a single 20 amp receptacle is allowed on a 15 amp circuit. 210.21(B)(1)

(B) Receptacles.
(1) Single Receptacle on an Individual Branch Circuit. A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.

The problem is that Table 210.21(B)(3) states that a 15 amp circuit may only have a receptacle rating not over 15 amps. But this is based on art. 210.21(B)(3) which states where connected to two or more receptacles.

So Trevor is correct

 

[acrwc10]

This is why when I buy single receptacles, for stock, I buy 20 amp. No issue when I need one, 20amp receptacle is no problem on a 15 amp circuit but the other way around is a problem.

 

[infinity]

I don't think so. Did you mean to say 15 amp receptacles are permitted on a 20 amp circuit but a 15 amp single receptacle is not permitted?

Nope but I could have said a 20 amp single receptacle is permitted on a 15 amp individual branch circuit for clarity. The individual part was implied since more than one 20 amp receptacle on a 15 amp circuit would be a violation.

 

[Sir String]

Quite right. Sorry fellas, for trying an incorrect correction.

Apparently you can put a single 20A receptacle on a 15A BC.

Which really seems wrong to me, but, well, there it is.

 

[acrwc10]

Quite right. Sorry fellas, for trying an incorrect correction.

Apparently you can put a single 20A receptacle on a 15A BC.

Which really seems wrong to me, but, well, there it is.

Not wrong, the point is to make sure the circuit will shut down before a failure occurs on parts of the system.