800 A Rule

[ggonza]

Does anybody know all the references that don't permit the provisions of 240.4(B). I know there's one on the secondary of a transformer. And also on a tap. And I think I've heard of one about a/c equipment. Any help would be great.

 

[iwire]

I am pretty sure they are all listed in 240.4

 

[Dennis Alwon]

A/c units are marked with max. ocpd but there are rules that limit the ocpd to a percentage and not more. 440.52 for a/c and 430.52 for motors.

Some rules allow the percentage and also let you go to the next size breaker.

If the calculated load of a feeder is not a standard size you can go to the next standard size breaker but the conductors must be sized to carry the calculated load. Thus if the calculated load is 87 amps then you would not be able to install #4 thhn on a 90 amp breaker because it is only good to 85 amps.