Sharing Inverter output and main house panel feeder conduit

[PRERA]

I have seen several installations where the Inverter output circuit is run inside the existing house panel main feeder all the way to the meter base for a supply side interconnection. provided all deratings and wire fill are taken in consideration, is this method in compliance with NEC?

 

[mwm1752]

Basically any conductor prior to the service disconnect shall not share it's raceway.
230.7 Other Conductors in Raceway or Cable
Conductors other than service conductors shall not be installed in the same service raceway or service cable.
Service Conductors. The conductors from the service point to the service disconnecting means.
Service Point. The point of connection between the facilities of the serving utility and the premises wiring.
Separately Derived System. An electrical source, other than a service, having no direct connection(s) to circuit conductors of any other electrical source other than those established by grounding and bonding connections.
Examples of separately derived systems include generators, batteries, converter windings, transformers, and solar photovoltaic systems, provided they have no direct electrical connection to another source.

 

[jaggedben]

Your description is a little light on details, but I agree it is probably not compliant.

BTW, a solar system may or may not be a separately derived system.

 

[PRERA]

Shareded conduit....

Shareded conduit....

Your description is a little light on details, but I agree it is probably not compliant.

BTW, a solar system may or may not be a separately derived system.

Thanks for your reply.

Trying to be more specific on the description, if it helps.

The premises ( a single family dwelling unit) is served from a pad mounted transformer across the street. There is a meter base with two breakers on the load side. One of the breakers feeds the main house panel, the other is spare. The feeder conduit from the meter base secondary breaker to the house main panel is embedded in concrete most of the way. The Inverter is located next to the panel and the PV system interconnection is intended to be supply side.

 

[ggunn]

I have seen several installations where the Inverter output circuit is run inside the existing house panel main feeder all the way to the meter base for a supply side interconnection. provided all deratings and wire fill are taken in consideration, is this method in compliance with NEC?

Is there a disco on the PV circuit out by the meter? That's the only way I would configure such a system.

 

[PRERA]

Is there a disco on the PV circuit out by the meter? That's the only way I would configure such a system.

Yes, as required by code.

 

[Carultch]

Yes, as required by code.

Is OCPD part of that disco?

The idea of not mixing service conductors and other conductors in the same raceway, is that if there is a fault on the service conductors, there is no upstream OCPD to clear it and keep it from faulting to the feeder conductors.

Once you pass the service disconnect / main OCPD, your conductors qualify as feeder conductors. Feeders can be mixed with inverter output circuits, provided that appropriate derates are considered.

 

[jaggedben]

Thanks for your reply.

Trying to be more specific on the description, if it helps.

The premises ( a single family dwelling unit) is served from a pad mounted transformer across the street. There is a meter base with two breakers on the load side. One of the breakers feeds the main house panel, the other is spare. The feeder conduit from the meter base secondary breaker to the house main panel is embedded in concrete most of the way. The Inverter is located next to the panel and the PV system interconnection is intended to be supply side.

If the PV is going to use the spare breaker, and all fill and deratings are taken into account as mentioned above, then I see no problem with this configuration. Neither of the circuits in the conduit are service conductors, and the inverter-output circuit is the same as any other AC circuit with respect to sharing a raceway.

 

[ggunn]

If the PV is going to use the spare breaker...

He said it was a supply side connection and that the spare breaker was on the load side.

 

[jaggedben]

He said it was a supply side connection and that the spare breaker was on the load side.

...by which I think he meant the load side of the meter.

Either way, if one breaker feeds the house, and other feeds the PV, and they are both fed from the same source, then the circuits can be in the same conduit.

 

[mwm1752]

BTW, a solar system may or may not be a separately derived system.[/QUOTE]

I do not believe it could be consider a utility even as a stand alone system.