Connection on the supply side

[Grouch1980]

In an interactive system, when you connect the solar PV inverter to the utility on the supply side of the building's service disconnecting means, is the PV system disconnect switch considered an additional service switch (right before tapping into the building service disconnect)? And is it part of the count of no more than 6 service switches?

 

[augie47]

It is allowed in addition to the (6).. 230.71.20.40,230. 82

 

[Grouch1980]

It is allowed in addition to the (6).. 230.71.20.40,230. 82

Thanks. you wrote 20.40... not sure what section that is referencing. So the PV disconnect IS considered a service switch then... requiring a main bonding jumper between neutral and ground, and also a GEC?

 

[augie47]

Typo 230.40 (referenced from 230.71)

 

[Grouch1980]

Thanks.

 

[jaggedben]

This has been controversial and may still be unclear. In the 2020 NEC 250.25 clarified grounding and bonding but left the definitional question ("Is it a 'service' disconnect?") unaddressed.
Mike Holt once said it's not a service disco but that was several code cycles ago and definitions have changed. I agree with Augie's line of code citations above, but see here for evidence against a consensus.

Bottom line is it's best to get the AHJ on the same page before you build anything you can't easily change.

 

[ggunn]

Bottom line is it's best to get the AHJ on the same page before you build anything you can't easily change.

Thumbs up emoji.

 

[LarryFine]

Thumbs up emoji.

 

[Grouch1980]

In the 2020 NEC 250.25 clarified grounding and bonding but left the definitional question ("Is it a 'service' disconnect?") unaddressed.

oh dear.

Bottom line is it's best to get the AHJ on the same page before you build anything you can't easily change.

oh dear again.

Thanks!

 

[electrofelon]

You can avoid all the confusion by adding another "normal" service disconnect per 230.40 ex #2 (or #3 if applicable) and connecting load side to that. You will have essentially the same capacity as a line side because you will use the sum of all breakers rule. That is what I do on almost all my systems because I need a combiner panel anyway.

 

[wwhitney]

You can avoid all the confusion by adding another "normal" service disconnect per 230.40 ex #2 (or #3 if applicable) and connecting load side to that.

If that "normal" service has no loads on it, is the resulting configuration any different from what you could do with a line-side PV disconnect? [Not sure if I may have asked you that before.]

Cheers, Wayne

 

[electrofelon]

If that "normal" service has no loads on it, is the resulting configuration any different from what you could do with a line-side PV disconnect? [Not sure if I may have asked you that before.]

Cheers, Wayne

I think pretty much.....do you agree? say I have a typical house with a 200 amp service. typically for a ground mount I would use 230.40 exception #3 and do a "service tap" at a pedestal or use a class 320 socket......usually put a 200A MB (which is the service disconnect) panel at the array and thats my combiner too. Sometimes I put a convenience outlet there which would chew up 20 amps, otherwise its all available for PV.

 

[jaggedben]

You can avoid all the confusion by adding another "normal" service disconnect per 230.40 ex #2 (or #3 if applicable) and connecting load side to that. You will have essentially the same capacity as a line side because you will use the sum of all breakers rule. That is what I do on almost all my systems because I need a combiner panel anyway.

You can't get a seventh handle with exception #2 though. That was the original question.

 

[electrofelon]

You can't get a seventh handle with exception #2 though. That was the original question.

Right, that is (about the only) advantage to the standard PV route. There is the grouping restriction as well too. Ex #3 kicks butt over standard for both of those though.

 

[wwhitney]

I think pretty much.....do you agree? say I have a typical house with a 200 amp service. typically for a ground mount I would use 230.40 exception #3 and do a "service tap" at a pedestal or use a class 320 socket......usually put a 200A MB (which is the service disconnect) panel at the array and thats my combiner too. Sometimes I put a convenience outlet there which would chew up 20 amps, otherwise its all available for PV.

Say you don't have the 20A receptacle but just have the service splice, conductors to the MB panel mounted at the ground mount array, and the PV system. Does that configuration comply both with the "PV line side connection" rules and the "additional service" rules? If so, it's indistinguishable which set of rules is applicable (other than this 6 vs 7 question).

Now if you add a 20A receptacle at the array, does that force it into the "additional service" paradigm, as a "PV line side connection" couldn't have any (non-monitoring?) loads? If so is that distinction spelled out anywhere?

Cheers, Wayne

 

[electrofelon]

Say you don't have the 20A receptacle but just have the service splice, conductors to the MB panel mounted at the ground mount array, and the PV system. Does that configuration comply both with the "PV line side connection" rules and the "additional service" rules? If so, it's indistinguishable which set of rules is applicable (other than this 6 vs 7 question).

Now if you add a 20A receptacle at the array, does that force it into the "additional service" paradigm, as a "PV line side connection" couldn't have any (non-monitoring?) loads? If so is that distinction spelled out anywhere?

Cheers, Wayne

Don't we need the PV disconnect within 10 feet of the line side connection point and then seperate N-G between that and the PV array under the PV rules? With the normal service rules I can run three wire service conductors an unlimited length. I often get these projects with far away PV arrays and run service conductors 700-800 feet to the 230.40 exception #3 service disconnect.

If you take my 230.40 exception #2 approach vs the traditional supply side connection approach, I agree they can be indistinguishable and I guess it just comes down to what you call it. As you may recall I have gotten lots of pushback from this approach on the forum. I have gotten some pushback from plan reviewers, I think three times, but i explained that it meets the "normal" rules without issue and as long as it meets the rules I should be able to qualify the conductors and disconnects that way, and they have always agreed.

 

[wwhitney]

Don't we need the PV disconnect within 10 feet of the line side connection point and then seperate N-G between that and the PV array under the PV rules?

2017 NEC 705.31 does require that in all cases for line side connections. 2020 NEC 705.11(C) requires it only for conductors inside a building, so it wouldn't restrict the installation under discussion. And glancing briefly at 2023 NEC 705.11, it looks like it basically says "treat it like a service."

Cheers, Wayne

 

[wwhitney]

I often get these projects with far away PV arrays and run service conductors 700-800 feet to the 230.40 exception #3 service disconnect.

Isn't Exception #5 more applicable, allowing you to do the same thing whether or not it's a dwelling unit sevice?

Cheers, Wayne