NEC 705.13

[Andy1099]

I was failed on a job and would like to clarify that i am correct or learn where i am incorrect: From a 125 amp service on a residence a main power feeder is ran from service disconnect (overcurrent) to Power System Controller. The new solar and battery backup are connected inside the PSC. From the PSC the main power feeder is ran to the distribution panel which has a buss rated at 125 amp. The inspector says i need to have a buss rated at 125% of the of the solar source circuit plus the 125 amp of the panel overcurrent. At 120% that would require a 150 amp buss. But from what i read of 705.13 the PCS (it is an Enphase controller) restricts the the amps to the feeder and buss rating. His code reference is 705.12(B)(3)(2) which makes no sense to me as the panel is fed with a single feeder-no other source as the solar source circuits land in the system controller.

 

[jaggedben]

I'm understanding you to be saying the inspector wants the backup loads panel to have a higher bus rating.

Do you have a 125A load breaker in the System Controller to protect the backup loads panel? It is designed to accept a CSR breaker for this.
Or alternatively, if the panel has main breaker in the panel it's about the same thing.

If you already have such a breaker protecting the panel the inspector is wrong.

If you don't, then you could fix the issue by installing such a breaker, not replacing the panel with a higher bus.

Either way I think the code citation is incorrect, but please clarify your code cycle because the numbering keeps changing.

 

[jaggedben]

Also Enphase's PCS listing doesn't apply here, especially if you haven't set up the PCS settings.

 

[jaggedben]

Sorry, does the service panel have a bus or just a breaker? Which panel is the inspector talking about?

 

[Andy1099]

Thanks for responding! The service is a main breaker-no panel. The main power feeder runs between the service 125 amp breaker and the system controller. There is no feeder breaker in the system controller. From the system controller the main power feeder runs to the distribution panel which has a 125 amp main breaker.

 

[Andy1099]

2023 nec

 

[jaggedben]

Then the inspector is wrong. He seems unclear on how the rules in 705 apply.

Also there is no 705.12(B)(2)(3) in the 2023 NEC. There is 705.12(B)(2) and 705.12(B)(3) and neither of them apply.