Branch circuit rating

[kevinware]

Hey everyone,
I'm sure some of you have seen my post entitled "more about voltage drop" posted in the calculation section. Well now I need some NEC input. My first post stated my concern about voltage drop of two 20 amp 120 volt circuits 200 feet away from the panel that I needed to come out of. Well to make a long story short, I decided with a little help from everyone's input here, to run my 20 amp circuits using # 10 THHN and use industrial grade 20 amp rated receptacles Levington part # 5362-I. According to manufactures specifications I can use wire sizes # 14 - # 10 stab through the back of the receptacle. So this is what I have. I have two 20 amp branch circuits with 20 amp OCPD using # 10 THHN wire terminated on industrial grade 20 amp receptacles. I tell my lead man that this is the way I was going to install these circuits and he tells me that I am in violation of the NEC because my receptacles are only rated for 20 amps and my # 10 is rated for 30 amps. To my understanding of the NEC the OCPD determines the rating of the branch circuit and not the wire size. So to my understanding as long as I use a 20 amp breaker it really doesn't matter what size wire I use, I still only have a 20 amp circuit and my industrial rated receptacles are rated 20 amp 125 volts but are just able to except a wire size up to a # 10. Am I wrong in my thinking?, please correct me... One more thing, there are no motor loads on these circuits. If my lead man is right can you give me the code reference?

Thanks,
Kevin

 

[jtester]

Re: Branch circuit rating

Kevin

You are correct. The OCPD provides the protection for downstream devices, 210.21 tells you it is OK. Actually the #10 THHN has many ratings, from 40 amps, the 90 degree C column value, down to 0 amps, the amount of current you could put through it in a 90 dgeree C ambient.

There is nothing wrong with using #10 on a receptacle circuit.

 

[eprice]

Re: Branch circuit rating

Kevin,

210.3 agrees with you

 

[bthielen]

Re: Branch circuit rating

Fact is, the NEC is a minimum standard. Oversizing the wire exceeds the requirement.

 

[john m. caloggero]

Re: Branch circuit rating

Hi Kevin: You are correct, the rating of the circuit is based on the size overcurrent device protecting the circuit. No. 10 awg cu, is allowed, provided the terminations are suitable to accept No. 10 awg. Larger size conductors are often utilized to compensate for voltage drop. You have done your homework