Load Side Tap Onto a 400A Split Bus Panel

[JimmysLimeade]

Hey guys,

I am designing a system where we have an existing 400A split bus MSP with (2) 200A main breakers that was rejected by the AHJ.

I'm stumped on what to do here, Are there any code sections that I can reference to make this system work as is? If not what should I change here?

Here is the line diagram and the rejection notes are clouded in red

Thanks in advance

 

[jaggedben]

Can you add a main breaker to the subpanel that's downstream of your tap?
Alternatively, can you install a subpanel or an additional fused disconnect next to the main to provide the overcurrent protection that 705.12(B)(1)(b) requires?

It seems to me that the lower comment about 705.11 vs. 705.12 is either:
1) a note to the inspector that the configuration is okay (except for the other part of the note),
or
2) a suggestion that you could try a supply side connection instead. I don't see that as being likely to be a feasible option with a 400A meter/main combo. But if you really have a separate meter socket, and if it's not a bolted on meter or something, that might be a better option.

(BTW, it seems a bit off that you have three 40A inverter breakers going through a 100A fused disconnect, unless your inverter outputs are in the sweet spot between 24.1 and 26.6 amps.)

 

[JimmysLimeade]

Can you add a main breaker to the subpanel that's downstream of your tap?
Alternatively, can you install a subpanel or an additional fused disconnect next to the main to provide the overcurrent protection that 705.12(B)(1)(b) requires?

It seems to me that the lower comment about 705.11 vs. 705.12 is either:
1) a note to the inspector that the configuration is okay (except for the other part of the note),
or
2) a suggestion that you could try a supply side connection instead. I don't see that as being likely to be a feasible option with a 400A meter/main combo. But if you really have a separate meter socket, and if it's not a bolted on meter or something, that might be a better option.

(BTW, it seems a bit off that you have three 40A inverter breakers going through a 100A fused disconnect, unless your inverter outputs are in the sweet spot between 24.1 and 26.6 amps.)

Thanks for the help here! I'll look into the sub-panel option or supply side connection and call the inspector to see if that would work. And you are dead on, the inverter output is 25A so this size works out perfectly.

Thanks again.

 

[ING23]

WHY AFTER THE 200 A MAIN BREAKER AND NOT BEFORE THE BREAKER? COULD YOU POST A PHOTO OF THE ACTUAL CONNECTION?

 

[ggunn]

WHY AFTER THE 200 A MAIN BREAKER AND NOT BEFORE THE BREAKER? COULD YOU POST A PHOTO OF THE ACTUAL CONNECTION?

Please quit shouting.

 

[JimmysLimeade]

WHY AFTER THE 200 A MAIN BREAKER AND NOT BEFORE THE BREAKER? COULD YOU POST A PHOTO OF THE ACTUAL CONNECTION?

This hasn't been installed yet and we called the plan reviewer who made us derate the main breaker to 150A and connect like this:


Again, thanks for the help here!