Split bus

[andrew.tkelly]

Hi,

How would you apply the 120% Rule to a main panel with a split bus? Let's use a 400A main panel with a 200A/200A split bus for this example.

Would you have to distribute the OCPD's evenly? Ex: 40A PV breaker on one bus, and a 40A on the other?

Or could you just put all 80A on one bus?

Regards,
Andy

 

[jaggedben]

Unless the documentation clearly indicated otherwise, I think you have to assume that each busbar set is 200A and can only handle 40A. If you need over 40A of backfeed then perhaps micro-inverters are a cheaper solution where they otherwise wouldn't be.

 

[andrew.tkelly]

Thank you for your reply.

On the panel sticker it says:

Meter Socket Rating: 400 amps continuous
Branch Rating: 400 amps
Rating of Device is sum total of Service Disconnects No. 1 and No. 2

Since the branch rating is 400 amps, I wonder if that would be evidence that I could put an 80 amp breaker on either bus, even though each part is protected by a 200 amp breaker?

I'm using Enphase IQ6 microinverters, but I'm trying to have a single disconnect in the main panel. It's a rather large system. I was hoping to have (4) 20 amp PV breakers in a subpanel (along with a breaker for the Enphase Envoy data monitoring), which goes to a single 100 amp AC disconnect, and then to the main panel. If I have to divide it between both busses, I'll have to have two subpanels, two AC disconnects, two Envoys, etc.).

Regards,
Andy

 

[ggunn]

Thank you for your reply.

On the panel sticker it says:

Meter Socket Rating: 400 amps continuous
Branch Rating: 400 amps
Rating of Device is sum total of Service Disconnects No. 1 and No. 2

Since the branch rating is 400 amps, I wonder if that would be evidence that I could put an 80 amp breaker on either bus, even though each part is protected by a 200 amp breaker?

I'm using Enphase IQ6 microinverters, but I'm trying to have a single disconnect in the main panel. It's a rather large system. I was hoping to have (4) 20 amp PV breakers in a subpanel (along with a breaker for the Enphase Envoy data monitoring), which goes to a single 100 amp AC disconnect, and then to the main panel. If I have to divide it between both busses, I'll have to have two subpanels, two AC disconnects, two Envoys, etc.).

Regards,
Andy

If you have a 200A bus protected by a 200A breaker, 40A is all the headroom you have to work with irrespective of whatever is upstream from it.

 

[jaggedben]

Ask the manufacturer to clarify the ratings of the different bus sections.

I don't see why you'd need two Envoys.

 

[ggunn]

Ask the manufacturer to clarify the ratings of the different bus sections.

I don't see why you'd need two Envoys.

I don't know for sure, but I have heard that the Envoys don't like to be installed in the MDP if the trunks are combined in a subpanel.

 

[jaggedben]

On the other hand, I've seen Envoy's communicate with the neighbor's inverters across the street. It all depends. I'd try it with one before spending the $$ on a 2nd.

 

[andrew.tkelly]

Thanks everyone! I called Eaton and discussed their panel with them. They said 40A on the upper disconnect section / 40A on the lower disconnection section was the max. PV allowed because although it's a 400A panel, only the meter socket is rated for 400A. The busses are 200A.

 

[Zee]

Thanks everyone! I called Eaton and discussed their panel with them. They said 40A on the upper disconnect section / 40A on the lower disconnection section was the max. PV allowed because although it's a 400A panel, only the meter socket is rated for 400A. The busses are 200A.

If you replace one of the 2p200 brkr with a 2p150A breaker assuming the 200A breakers can be replaced properly per manufacturers rules....:thumbsup:
, you can add 90A!

But I bet you are all done with the job by now....late reply on my end.:dunce: