PV backfed breakers

[Ponchik]

Does 690.64 (B)(7) (NEC 2008) mean that the back fed breaker can not be next to the main breaker and has to be as far away from the main as possible?

I believe the bolded section does not refer to the main service disconnect. Does it?

Thank you.


(7) Inverter Output Connection. Unless the panelboard is
rated not less than the sum of the ampere ratings of all overcurrent
devices supplying it, a connection in a panelboard
shall be positioned at the opposite (load) end from the input
feeder location or main circuit location. The bus or conductor
rating shall be sized for the loads connected in accordance
with Article 220. In systems with panelboards
connected in series, the rating of the first overcurrent device
directly connected to the output of a utility-interactive
inverter(s) shall be used in the calculations for all busbars
and conductors. A permanent warning label shall be applied
to the distribution equipment with the following or equivalent
wording:

 

[Ponchik]

I removed post.
duplicated.

 

[SolarPro]

Correct. Unless the sum of the main CB and the PV CB is less than the rating of the panel, the PV CB needs to be located at the bottom of the panel board (assuming the main CB is on the top). So if you are applying the "120% rule" to make the interconnection, the breakers feeding the bus need to be located at opposite ends of the bus. This prevents overloading of the bus.

 

[jaggedben]

...

I believe the bolded section does not refer to the main service disconnect. Does it?

...

(7) Inverter Output Connection. Unless the panelboard is
rated not less than the sum of the ampere ratings of all overcurrent
devices supplying it, a connection in a panelboard
shall be positioned at the opposite (load) end from the input
feeder location or main circuit location. .
... :

"Connection" refers to the PV output. "Feeder location or main circuit location" refers to the utility supply to the panel. It would refer to the main service disconnect if the panel in question is a service panel.

 

[Ponchik]

Does this apply to all installation or commercial only?
Or under certain condition single family dwelling is exempt?

Thanks.

 

[jaggedben]

Does this apply to all installation or commercial only?
Or under certain condition single family dwelling is exempt?

Thanks.

All installations.

(I believe some of the interconnection rules used to be for commercial only, but that was a couple of code cycles ago.)

 

[acrwc10]

Does 690.64 (B)(7) (NEC 2008) mean that the back fed breaker can not be next to the main breaker and has to be as far away from the main as possible?

I believe the bolded section does not refer to the main service disconnect. Does it?

Thank you.


(7) Inverter Output Connection. Unless the panelboard is
rated not less than the sum of the ampere ratings of all overcurrent
devices supplying it, a connection in a panelboard
shall be positioned at the opposite (load) end from the input
feeder location or main circuit location. The bus or conductor
rating shall be sized for the loads connected in accordance
with Article 220. In systems with panelboards
connected in series, the rating of the first overcurrent device
directly connected to the output of a utility-interactive
inverter(s) shall be used in the calculations for all busbars
and conductors. A permanent warning label shall be applied
to the distribution equipment with the following or equivalent
wording:

Why would this not include the main disconnect? It is an over current device supplying the panel.
This means "OPPOSITE END" not "as far away as I can get it". Earlier this year one of the inspectors I know sent this question to the NEC, asking if you could use the 120% rule from Sec. 705.12(D)(7) on a center fed panel. The NEC's reply was, "if the panels main breaker is center fed on the buss than there is no way the PV input could be at the OPPOSITE end fo the buss. The sum of the input breaker must not exceed 100% of the buss rating."
This section has servived a few code cycles now, I don't see it going away anytime soon.