people qouting code

[chriskellaway]

does it state and what section that you cant exceed 80% ampacity of branch circuit overcurrent protection rating

when sizing your conductor?

Ive heard this but cant find the facts.

Do you get sick and tired of people qouting code with out telling you the article and section which they are

explaining. Thats how rumors get started.

I take it with a grain of salt and look it up for myself.

 

[jwelectric]

210.19 covers the conductor and 210.20 covers the overcurrent device

 

[kwired]

That is not exactly what the rule is but works most of the time.

The general rule is that conductors "shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load".

This is found in 210.19 for branch circuits, 215.2 for feeders, and 230.42 for services. It is worded mostly the same in all three, I quoted from 210.19.

This is for conductor ampacity. Now go to 240.4 and you will find that conductors "shall be protected against overcurrent in accordance with their ampacities specified in 310.15". Then don't forget the 15,20,30 amp protection for 14,12,10 AWG as required by 240.4(D).

If the load is not a continuous load a load of 20 amps can be protected with a 20 amp overcurrent device. If it is a continuous load then a 20 amp load must have conductor ampacity and overcurrent protection that is 1.25 times higher or 24 amps. Next standard overcurrent device is allowed - 25 amps.

 

[infinity]

I would also take a look at 210.23 (100% rule) and 210.23(A)(1) for an 80% rule.

 

[LEO2854]

does it state and what section that you cant exceed 80% ampacity of branch circuit overcurrent protection rating

when sizing your conductor?

Ive heard this but cant find the facts.

Do you get sick and tired of people qouting code with out telling you the article and section which they are

explaining. Thats how rumors get started.

I take it with a grain of salt and look it up for myself.

Do you get sick and tired of people qouting code with out telling you the article and section which they are

explaining. Thats how rumors get started.

Yes it does ,Ask them for the article and section.