Backfeed at distribution panel with no main breaker

[Zyb]

Hi,

do I need a Main Breaker before I can backfeed my PV? can I use 400A fused Disconnect instead? Thank you

 

[jaggedben]

No, you don't. It's a supply side connection. 705.11, or 705.12(A) in older codes.

 

[jaggedben]

Actually if you are on the 2020 NEC the panel may no longer be a compliant panel, and that could be a pitfall. 2020 NEC requires service disconnects to be in separate enclosures or partitioned. But it's unclear on how an AHJ should enforce a new connection in an existing panel.

As far as the interconnection rules go (art 705) it's fine.

 

[Zyb]

No, you don't. It's a supply side connection. 705.11, or 705.12(A) in older codes.

Thank you @jaggedben. do I need to place the 60A breaker opposite of the Line?

 

[Zyb]

@jaggedben wouldn't my 60A PV exceed the 400A rating of the main distribution panel? hence the sum of the existing breakers already exceed 400A amps

 

[ggunn]

@jaggedben wouldn't my 60A PV exceed the 400A rating of the main distribution panel? hence the sum of the existing breakers already exceed 400A ampsThank you
[/QUOTE]

[QUOTE="Zyb, post: 2790331, member: 175992"]
@jaggedben. do I need to place the 60A breaker opposite of the Line?

No and no. The opposite end of the bus rule is in 705.12 and only for load side connections; you are considering, as jaggedben pointed out, a supply side connection. Likewise, the rule for the sum of breaker ratings not exceeding the bus rating is also in 705.12.

 

[jaggedben]

@jaggedben wouldn't my 60A PV exceed the 400A rating of the main distribution panel? hence the sum of the existing breakers already exceed 400A amps

See 230.90 exception 3. Since your PV is not a load it doesn't add to the calculated load, and it doesn't change how much current can flow to the load breakers.

 

[GoldDigger]

The OP shows two alternative circuits.
The one on the left is a supply side connection, as the bus wires in the panel are service conductors. As long as supply side connections are allowed by your POCO and AHJ, it is compliant as drawn.
The one on the right would be a load side connection, but would require rewiring the existing main panel as a subpanel, separating neutrals from EGCs. Since the backfed breaker is at the opposite end of the bus from the OCPD protected feed, the opposite-end condition is met.