Overcurrent Protection

[samir]

This question may seem a little dump but it always confuses me.

The upstream cable of a overcurrent protective device is 3 sets of 350MCM Copper (930A). Should the downstream overcurrent device be set at 930A or below to protect the cable?
I dont see any exception in NEC for the conductor protection when it is upstream of the OCPD when rated over 800 AMps. SO I think it should be sized to protect the conductors. Just wanted to be sure if I am interpreting it correctly.

 

[Dennis Alwon]

I agree that over 800 amps you cannot use the next standard size breaker so either increase the conductors or lower the overcurrent protective device .

 

[don_resqcapt19]

I really don't understand the question. The conductors have to be protected at or below there ampacity at the supply point unless the fall under the tap rules in 240.21(B) or in the case of transformer secondary conductors by the rules in 240.21(C).