Receptacle Limits on a brach circuit per NEC

[PwrCntEE]

I am missing something in the NEC. #220.3.B.9 states that for a 20A circuit they allow 13 receptacles. This is only if they allow the breaker to be loaded 100%. I thought I had to size the breaker to 125% of the load or limit the load to 80% of the breaker. By this method, the limit is 10 for a 20A circuit. I must me missing an exeption; can anyone point it out? (I am dealing Industrial, but what about commercial/Residential?)

Regards

 

[rbulsara]

You confusing branch or feeder circuit load calculations with number of receptacle that can be on a circuit.

In fact there is no limit by NEC as to how many repectacels you can put on a circuit. The requirement is that if there are more than two receptacles on a circuit, the receptacle ratings shall not be less than requried by NEC table, 210.21.B.3

Refer to 210.21 and 210.23.A.1 also. It is up to the desinger to make sure, within reasons, that at a given time the circuit will not be overloaded.

 

[BJC]

Section 220.3 states the load for a receptacle shall be calculated at 90 VA for each receptacle ( of 180 VA for a duplex receptacle).
A 20 amp circuit at 180 VA per receptacle the maximum number of duplex receptacles that can be connected to one circuit is (120*20)/180 = 13.333.
Good design practice is to know the loads and circuit the receptacles accordingly.

 

[PwrCntEE]

Hit the nail on the head.....Thanks!

 

[advidana]

Maybe I missed something but I did not read that 13 outlet are permitted in NEC2002 Article 220.3(B)(9). Yes 10 general purpose outlets for 20 amp circuits for commerical and industrial applications.

As for Dwellings- the 180 va per receptacle does not apply. It is figured into the general lighting load calc. But, most local codes use the 10 outlet rule anyway for 20 amp circuits.

There is a lot of different views about this section. Check with your local building department plan check or inspection for their version.

 

[advidana]

I stand corrected 13 outlets if for non continous loads in industrial and commerical applications.

 

[PwrCntEE]

Sorry, I miss stated. I have the handbook which has an exhibit 220.4 just below 220.3(B)(9). I don't think the code puts a limit in writing (as stated above); hence, when I saw the example in the handbook, I saw another interprutation.