Tested and listed for backfeed

[SolarAlternativesDesign]

We have a Murray JA208PS service panel where the main bus bar and main breaker are rated too low for backfeeding in the planned inverter output circuit. The panel has an additional breaker slot that connects to the service at the meter socket. It looks like an opportunity to place the PV backfed breaker, BUT Siemens tech support says that the connection was not tested and identified and listed for PV backfeeding because it was manufactured several years ago, before PV backfeeding was common.
Should a PV design consultant automatically rule out using that connection because it is not identified and listed for the purpose?

 

[Smart $]

You mentioned using the "extra" slot. Is it just busing back to meter socket? If yes, it will handle AC current no matter which direction the power is going. Current is current to a bus. Chances are the same with any breaker you install, as long as it is not marked LINE and LOAD.

 

[SolarAlternativesDesign]

You mentioned using the "extra" slot. Is it just busing back to meter socket? If yes, it will handle AC current no matter which direction the power is going. Current is current to a bus. Chances are the same with any breaker you install, as long as it is not marked LINE and LOAD.

Yes. it's a breaker mounting on a plate above the main bus and main breaker (sorry I don't know the right terminology), and the conductors go directly to the meter socket.

 

[Smart $]

Yes. it's a breaker mounting on a plate above the main bus and main breaker (sorry I don't know the right terminology), and the conductors go directly to the meter socket.

Well the conductors and terminal-stabs certainly can't tell which direction power is going.

 

[jaggedben]

The NEC does not require anything besides circuit breakers to be tested as suitable for backfeed. There isn't even a UL standard for anything else as far as I know. It makes no more sense to ask if this connection is listed and identified for backfeed than about a load side connection or any other manufactured connection. That is a supply side connection gifted to you and you may absolutely use it up to it's rating.

 

[electrofelon]

That is a supply side connection gifted to you and you may absolutely use it up to it's rating.

That is quite the interesting panel, never seen anything like it. Indeed, that is what PV installers dream about

 

[jaggedben]

That is quite the interesting panel, never seen anything like it. Indeed, that is what PV installers dream about

It's interesting because Siemens has made a 'solar ready' line of panels that look awfully similar. I doubt they've tested those panels for backfeed either. (Again, what UL standard would that be?)

There's also a Homeline series of panels with 50A 'auxilliary service disconnects, and I believe I've seen an Eaton as well. This is not to mention the numerous meter-main panels that are set up for 2-3 main breakers and no branch breakers. I think in most cases the mfrs were thinking about air conditioners, not solar.

 

[electricguy61]

It's interesting because Siemens has made a 'solar ready' line of panels that look awfully similar. I doubt they've tested those panels for backfeed either. (Again, what UL standard would that be?)

There's also a Homeline series of panels with 50A 'auxilliary service disconnects, and I believe I've seen an Eaton as well. This is not to mention the numerous meter-main panels that are set up for 2-3 main breakers and no branch breakers. I think in most cases the mfrs were thinking about air conditioners, not solar.

I believe that is an Siemans panel

 

[jaggedben]

I believe that is an Siemans panel

He said Murray but since Siemens owns Murray it almost amounts to the same thing.

 

[Smart $]

He said Murray but since Siemens owns Murray it almost amounts to the same thing.

Hmm... guilty by association.

 

[SolarAlternativesDesign]

The NEC does not require anything besides circuit breakers to be tested as suitable for backfeed. There isn't even a UL standard for anything else as far as I know. It makes no more sense to ask if this connection is listed and identified for backfeed than about a load side connection or any other manufactured connection. That is a supply side connection gifted to you and you may absolutely use it up to it's rating.

That makes sense. I suppose most or all of the load side connection PV systems go through a meter socket connection that was never tested or listed for backfeeding. But the Siemens tech support guy sounded ominous and I wondered if there was some listing that I didn't know about.

Thanks very much.

 

[jaggedben]

That makes sense. I suppose most or all of the load side connection PV systems go through a meter socket connection that was never tested or listed for backfeeding. But the Siemens tech support guy sounded ominous and I wondered if there was some listing that I didn't know about.

Thanks very much.

Yeah well, just don't mention anything to the AHJ.
And you're welcome.

 

[pv_n00b]

I've heard descriptions of this type of panel before. They are used more in the South where residential HVAC is a big load and the single breaker position was for an HVAC system. If you find one that is not connected it's a clean supply side interconnection. I have never seen one myself.

My experience has been that if you ask a large manufacturer of electrical equipment if you can do something with their equipment that they did not design it specifically to do they will tell you you can't do whatever you want to do. They are very risk adverse and have no motivation to approve anything off the books.