help clarifying 210.21. and 210.23

[mjmike]

Lets say we have a microwave that is plugged in and is portable. It is a 20A branch circuit with a duplex receptacle. This means 210.23.A.1 is applicable with a max load of 16A.correct?

It also means 210.21.B.2 is applicable correct?

Now, Lets say we have a microwave that is plugged in fixed in place. It is a 20A branch circuit with a duplex receptacle. 210.23.A.2 is not applicable because there is no light fixtures and there is no other cord/plug portable loads. Therefore, per 210.21.B.2, the max load is still 16A (per table 210.21.B.2) correct?

What if there is a 20A branch circuit with a single receptacle (1 outlet; not duplex), could the microwave be a 20A max load? If yes, what if the connected load would be a continuous load like a portable heater? If it is say 19A load, the breaker would trip over time (continuous load).

Thanks

 

[augie47]

If it were a single receptacle, the outlet could be on a 20 amp breaker per 210.21(B)(1).
If the load was continuous, 210.20(A) would apply.
Just as a foot note, I don;t think a portable heater is considered continuous.

 

[mjmike]

If it were a single receptacle, the outlet could be on a 20 amp breaker per 210.21(B)(1).

Thanks, but I understand that. I am asking that wat if the branch circuit as a single 20A receptacle on a decicated branch circuit. Can the equipment plugged into that draw the full 20A; such as say a microwave operating at 19.5A as an example.

Once the single 20A receptacle becomes a duplex, now the max allowable plug in load is 16A per 210.21.B.2 if portable. If the plugged in load were permenant and there was an additional portable load plugged in, the max load would only be 10A for the permenant equipment per 210.23.A.2.

If the load was continuous, 210.20(A) would apply.
Just as a foot note, I don;t think a portable heater is considered continuous.

Why would a plugged in portable heater not be considered a continuous load? I have seen people run portabel heaters for many hours at a time?


I guess, to summarize, if I have a single receptacle at 20A on a 20A circuit can the full load on that circuit be 20A but if the receptacle were to be a duplex, then the max load would be 16A?

 

[Smart $]

...
I guess, to summarize, if I have a single receptacle at 20A on a 20A circuit can the full load on that circuit be 20A but if the receptacle were to be a duplex, then the max load would be 16A?

Not correct. The limit of 210.23(A)(1) is 80% per any one cord-and-plug-connected utilization equipment. The second receptacle can be utilized for the balance. These rules for equipment loads are essentially superflous, being they are subject to user's discretion for what gets plugged into them... and we all know how that goes

 

[mjmike]

Not correct. The limit of 210.23(A)(1) is 80% per any one cord-and-plug-connected utilization equipment. The second receptacle can be utilized for the balance. These rules for equipment loads are essentially superflous, being they are subject to user's discretion for what gets plugged into them... and we all know how that goes

I think I would disagree. Per 210.21.B.2 for the duplex receptacle, the max load of all equipment is 16 amps (80%). If you have a cord/plug load that draws 80%, then there could be no additional load utilizing the balance.

 

[david luchini]

I think I would disagree. Per 210.21.B.2 for the duplex receptacle, the max load of all equipment is 16 amps (80%). If you have a cord/plug load that draws 80%, then there could be no additional load utilizing the balance.

I think Smart$ has this right. You are misreading 210.21(B)(2).

210.21(B)(2) says "A Receptacle shall not supply a total..load in excess of the maximum specified in Table 210.21(B)(2)."

That is to say a single receptacle. It doesn't say "all receptacles" shall not supply a total load...

 

[Smart $]

Deleted

 

[mjmike]

I think Smart$ has this right. You are misreading 210.21(B)(2).

210.21(B)(2) says "A Receptacle shall not supply a total..load in excess of the maximum specified in Table 210.21(B)(2)."

That is to say a single receptacle. It doesn't say "all receptacles" shall not supply a total load...

Yes, I did mis-read. Thanks for clarifying.

Now what if it was a single 20A receptacle and not a duplex, can if have the full 20A cord/plug load connected to it?

 

[david luchini]

Yes, I did mis-read. Thanks for clarifying.

Now what if it was a single 20A receptacle and not a duplex, can if have the full 20A cord/plug load connected to it?

If you mean a single 20A receptacle on an individual branch circuit, then yes. See 210.23

An individual branch circuit shall be permitted to supply any load for which it is rated.

 

[mjmike]

Thanks.