2p60A PV on 200A residential service

[Zee]

(E) MBO service with 2p200A main brkr. only.
Solar needs to tie in with 2p60A brkr.

If I install a new subpanel, (between the Service and (E) subpanel inside house) fed by (E) 2p200A main brkr, and installed a 2p175 as a main brkr in this new subpanel and my new PV 2p60 as a load breaker...... does that meet NEC?

I would like to replace MBO service, but it is in a "doghouse", and limitations - both physical and AHJ - exist.

 

[Zee]

QUESTION 2:
If I were to do a supply side tap....could I use a load center with a main breaker instead of the standard 2p60A fusible disco switch?

Say a 100A rated load center (fed by #6 min conductors I believe is still the rule.... with a 2p60 main brkr in it and another 2p60 PV breaker on the load side busbars for inverter output.

If so, what minimum SCIR rating on the new 2p60A main breaker would be needed nowadays?

 

[Smart $]

QUESTION 2:
If I were to do a supply side tap....could I use a load center with a main breaker instead of the standard 2p60A fusible disco switch?

Say a 100A rated load center (fed by #6 min conductors I believe is still the rule.... with a 2p60 main brkr in it and another 2p60 PV breaker on the load side busbars for inverter output.

I think most AHJ will look at that as a load-side interconnection.

Do you need extra breaker spaces?

Why not save all the hassle and do a simple line-side connection?

 

[electricalist]

The situation we run into is.
If there's a 200 amp panel , 60 amps back fed any way you can come up with. The AHJ around here will want load calcs and to verify it.
Add a sub panel in the mix and it doesn't help.
Line side tap the fist means of disconnect, install the service disc for the PV drive 2 ground rods and call it for inspection.


Sent from my iPhone using Tapatalk

 

[jaggedben]

Since the service equipment is not a panelboard, it's not subject to the 120% rule and the subpanel idea works fine. AHH may indeed want load calcs but that's unlikely to hold you up ultimately.

In my opinion there's no reason you can't do a supply-side connection to a main breaker panel but I've run into one AHJ whi disagreed. It wasn't worth aguing over.

 

[Zee]

I think most AHJ will look at that as a load-side interconnection.

Do you need extra breaker spaces?

Why not save all the hassle and do a simple line-side connection?

Frankly, I should have just done a line side tap. However, I promised a new panel to the customer....shame....it will cost me much more $$$.
yes, extra breaker spaces are nice for eventual home-owner loads (EV, hot tub, convenience outlet, lights, etc)

this IS a line side connection. The first OCPD would be a 60A breaker instead of 60A fuses. what is the diff.?

 

[Zee]

Since the service equipment is not a panelboard, it's not subject to the 120% rule and the subpanel idea works fine. AHH may indeed want load calcs but that's unlikely to hold you up ultimately.

In my opinion there's no reason you can't do a supply-side connection to a main breaker panel but I've run into one AHJ whi disagreed. It wasn't worth aguing over.

1. OK, that is what I remember.
Just to be sure:
the feeder conductors from (e) 200A MB to s.p. will have 200 + 60 feeding it, which is >120%...... and is that OK per most recent Code cycles? (previous Code used to say conductor and busbar affected by 120% rule - sic)


2. Yes, I feel the same way. I see no reason why a breaker isn't OK vs fused disco for a line side tap. I just don't see it done. So I wondered.....

 

[ggunn]

2. Yes, I feel the same way. I see no reason why a breaker isn't OK vs fused disco for a line side tap. I just don't see it done. So I wondered.....

It depends on the AHJ. All the ones I deal with require a lockable bladed disco with a visible break in the current path whether it is line or load side interconnected.

 

[Smart $]

Frankly, I should have just done a line side tap. However, I promised a new panel to the customer....shame....it will cost me much more $$$.
yes, extra breaker spaces are nice for eventual home-owner loads (EV, hot tub, convenience outlet, lights, etc)

this IS a line side connection. ...

It IS until someone puts a load breaker in that nice new panel with extra spaces. While the AHJ should inspect to what is there now versus what could be there later, they do have to take into consideration what a [non-qualified electrician] homeowner may do without getting a permit and subsequent inspection.

 

[ggunn]

It IS until someone puts a load breaker in that nice new panel with extra spaces. While the AHJ should inspect to what is there now versus what could be there later, they do have to take into consideration what a [non-qualified electrician] homeowner may do without getting a permit and subsequent inspection.

I don't quite understand what you mean. If the interconnection is between the service and the service disconnecting means it is a line side connection. If it is behind the service disconnecting means it is a load side connection. Load breakers are inconsequential; I don't see how adding loads can change the nature of the interconnection.

 

[Dennis Alwon]

Just change the main breaker from 200 to 175 amps if the load allows. Is the bus rated 200 amps or 225 amps?

 

[jaggedben]

I don't quite understand what you mean. If the interconnection is between the service and the service disconnecting means it is a line side connection. If it is behind the service disconnecting means it is a load side connection. Load breakers are inconsequential; I don't see how adding loads can change the nature of the interconnection.

A potentially consequential difference would that if you stick regular loads in then it becomes undeniably a regular service disconnect. So it has to be grouped with the existing disconnect, (and can't be disco number seven).

Just change the main breaker from 200 to 175 amps if the load allows. Is the bus rated 200 amps or 225 amps?

If only he hadn't promised the customer a new panel. Pesky customers who think becuase you can do electrical work they can ask you to do more electrical work.

 

[Smart $]

I don't quite understand what you mean. If the interconnection is between the service and the service disconnecting means it is a line side connection. If it is behind the service disconnecting means it is a load side connection. Load breakers are inconsequential; I don't see how adding loads can change the nature of the interconnection.

My reply is in regards to this post...

QUESTION 2:
If I were to do a supply side tap....could I use a load center with a main breaker instead of the standard 2p60A fusible disco switch?

Say a 100A rated load center (fed by #6 min conductors I believe is still the rule.... with a 2p60 main brkr in it and another 2p60 PV breaker on the load side busbars for inverter output.

 

[Smart $]

... Pesky customers who think becuase you can do electrical work they can ask you to do more electrical work.

It's not so much they ask you to do more electrical work. It's that they want more electrical work and equipment than they want to pay for. :happyyes:

 

[Zee]

Dennis, I am a big fan of the 200 to 175 switcharoo...... and it is really AMAZING how many many services I find that have an (E) 175A main breaker (on my plans) in a 200A rated panel. Just amazing.:roll: And it just so happens that is exactly what the PV needs, as the PV always seems to be quite large, 60A in these specific cases. Quite fortuitous.:angel:

In this case, however, it is a Main Breaker Only panel, so either a supply side connection or new subpanel are needed.

BTW - For the new subpanel, I found a real nice 12-space and 225A rated load center that is only about 2 feet tall! Square D.
Kinda hard to get a decently small sized one, and not a four-foot tall, 40 bazillion space load center in the 225A rated variety. Am happy with find.:thumbsup:


Jaggedben, for future reference, I like the idea of putting in a load center as a supply side connection...and if the homeowner wants to add load breakers in the future, not my problem. In most cases this is co-located with MSP in any case, so no real worries.