PV Feeder Protection Question

[AKSolar]

There is a lot of language in 690 regarding how to set the rating of the DC protection device, with various sizing current values. Can you please confirm that at the end of the day, the fuse/breaker needs to be rated to protect the derated ampacity of the conductors (after conditions of use) per NEC 240? Or is there some language in 690 that allows you to circumvent this?

Also, how might NEC 240.101(A) apply in the case of DC feeders? It seems to indicate that as long as the fuse is less than 3x the conductor ampacity, it is okay.

Thank you,

 

[jaggedben]

There is a lot of language in 690 regarding how to set the rating of the DC protection device, with various sizing current values. Can you please confirm that at the end of the day, the fuse/breaker needs to be rated to protect the derated ampacity of the conductors (after conditions of use) per NEC 240? Or is there some language in 690 that allows you to circumvent this?

Yes it does, and no there isn't.

Also, how might NEC 240.101(A) apply in the case of DC feeders? It seems to indicate that as long as the fuse is less than 3x the conductor ampacity, it is okay.

Thank you,

I think it is saying that for cases where the code otherwise allows a fuse to be rated higher than conductors, then there's a 3x limit for over 1000V. But since PV is not one of those cases in the code, it doesn't apply to your questions.

 

[jaggedben]

[Duplicate]