PV connection

[ING23]

This customer has a Main Panel with 2 Main Breaker or the option to add a 2nd Main Breaker . 200 Amps is protecting the bus bar where all house branches circuit breaker are connected. The other spot for the other main Breaker is empty . My question is : can I install a 100 amp breaker to feed a 100 Main lug subpanel and install my 60 Amp Solar breaker there. If this is possible what part of the 705.12 Chapter allowed me to do this?

 

[jaggedben]

Why not just install the 60A solar breaker directly in the empty service panel main breaker slot? Does the slot require a breaker type that's 100A or larger?

Using the empty main breaker slot is a supply side connection. 705.12(A) in the 2017 NEC or earlier and 705.11 in the 2020 or 2023 NEC.

The 100A subpanel does not meet the '120% rule', but it meets the 'sum of all breakers rule' if there are no other breakers in it. Need to know your code cycle to cite the exact sections of 705.12 because the numbering keeps changing. Still, you haven't explained the purpose of the subpanel.

 

[wwhitney]

Need to know your code cycle to cite the exact sections of 705.12 because the numbering keeps changing.

Up.codes says Nevada is on the 2017 NEC. So if the project is in Nevada as the OP is, then adding the second breaker to the MLO service panel would be allowed. Under the 2020, that's not a viable option anymore.

[OK, maybe under the 2020 it's ambiguous, as you could get away with calling the 60A breaker something other than a service disconnect. But under the 2023 NEC it's not viable anymore.]

Nevada Electrical Code 2017 based on the NFPA 70, 2017

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

Cheers, Wayne

 

[ggunn]

Up.codes says Nevada is on the 2017 NEC. So if the project is in Nevada as the OP is, then adding the second breaker to the MLO service panel would be allowed. Under the 2020, that's not a viable option anymore.

Under "you touch it you fix it", when the 2020 NEC is in force the AHJ may require you to add an external service disconnect, rendering the question moot.

 

[wwhitney]

Under "you touch it you fix it", when the 2020 NEC is in force the AHJ may require you to add an external service disconnect, rendering the question moot.

Agreed if the 4 position main panel is inside. But outside is more likely around here; not sure what Nevada practice is.

Cheers, Wayne

 

[solarken]

This customer has a Main Panel with 2 Main Breaker or the option to add a 2nd Main Breaker . 200 Amps is protecting the bus bar where all house branches circuit breaker are connected. The other spot for the other main Breaker is empty . My question is : can I install a 100 amp breaker to feed a 100 Main lug subpanel and install my 60 Amp Solar breaker there. If this is possible what part of the 705.12 Chapter allowed me to do this?

I am a little confused by your OP. Can you clarify what the customer has? What type of panel is the Main Panel? Is there only two Main Breakers in the Main Panel, and are the House branch circuits in a different subpanel? Or is this a split-bus panel? Where is the 200A breaker that you reference is protecting the bus bar feeding the house circuits.

 

[hitehm]

Hopefully I can be some help here. The OP is a workmate of mine and is having an issue attaching pics. Here is a pic of the panel and a diagram of what we are suggesting, which is to use 705.12 bus rule C instead of B with a small MLO subpanel that will only have the solar breaker. We found a 100A main that will fit in the top aux main slot so it will only be protecting the sub. To answer others ?s: There is no 60A main for that panel so we can't do "supply side", NV is on NEC 2017, 705.12 B rule is not an option, we are over.







View attachment 2564324

 

[curt swartz]

The second service disconnect position in that picture is not designed for a TQD breaker. It will hold a plug-in THQL breaker.

 

[ggunn]

I'm not sure if I am reading this correctly, but you still have to comply with 705.12 in the main panel. If it has a 200A bus and a 200A main breaker you can only feed 32A of solar into it on the load side of the main breaker no matter how it gets there, and however it is getting in must be on the opposite end of the bus from the main breaker. Feeding the PV circuit in through a subpanel makes no difference.

 

[wwhitney]

I'm not sure if I am reading this correctly, but you still have to comply with 705.12 in the main panel.

In the proposed configuration, there are two separate service disconnects. The equipment manufacturer has installed dual lugs (or the equivalent) on the load side of the meter, and brought one set of factory conductors to the main breaker with distribution panel below it that has already been populated in the photo. The other set of factory conductors goes to that small 2 position bus at the top of the enclosure that is currently unused.

So the PV is on its own service disconnect, and none of the PV current is flowing through the existing main breaker or the breakers on the bus below it. If the single enclosure shown in the photo were separated into two compartments with separate covers, then I believe that equipment would also comply with the 2020 requirements. Although there would (ideally) be a place to land GECs and install an MBJ upstream of both service disconnects.

Cheers, Wayne

 

[jaggedben]

To repeat, you're allowed to use that unused service disconnect provision for a supply side connection. And if you're still on the 2017 code or equivalent, there's no issue with the panel not being up-to-date for compliance with the 2020 NEC.

(I'm hoping that AHJs will be reasonable about 'grandfathering' exisiting panels when the 2020 NEC is in force, but I'm not counting on it.)

 

[BackCountry]

Hopefully I can be some help here. The OP is a workmate of mine and is having an issue attaching pics. Here is a pic of the panel and a diagram of what we are suggesting, which is to use 705.12 bus rule C instead of B with a small MLO subpanel that will only have the solar breaker. We found a 100A main that will fit in the top aux main slot so it will only be protecting the sub. To answer others ?s: There is no 60A main for that panel so we can't do "supply side", NV is on NEC 2017, 705.12 B rule is not an option, we are over.




View attachment 2564325


View attachment 2564324View attachment 2564326

Triple tap on the previous posts:

This is a common 400amp (320 continuous) CSED panel, the dedicated second disconnect is unused, you’re good to back feed up to 200A using a dedicated AC combiner panel with the appropriate labeling.

Just make sure you pre apply with your utility if your PV sizing is greater than 10kw, the transformer could be too small and then you’ll get stuck with some upgrade fees.

 

[jaggedben]

Just make sure you pre apply with your utility if your PV sizing is greater than 10kw, the transformer could be too small and then you’ll get stuck with some upgrade fees.

Is that Nevada specific? AFAIK in California if you're on an shared transformer and the system is under 30kW they can force you to wait for the upgrade, but not to pay for it.

 

[hitehm]

The second service disconnect position in that picture is not designed for a TQD breaker. It will hold a plug-in THQL breaker.

That's VERY helpful Curt, and would really simplify things greatly. I hate to question anyone helping us out but are you absolutely sure a THQL fits on that top disco? If so it's worth changing the plans and waiting on an updated permit. Admittedly, we rarely use GE breakers and mistakenly assumed from the pics the unused disconnect took a "main" only breaker. This is why we didn't think a line side connection was possible.

So just to clarify, we can snap a THQL 60A solar breaker on the top disconnect for a true LINE SIDE connection and avoid dealing with a sub panel and any load side rules, correct?

 

[jaggedben]

That's VERY helpful Curt, and would really simplify things greatly. I hate to question anyone helping us out but are you absolutely sure a THQL fits on that top disco? If so it's worth changing the plans and waiting on an updated permit. Admittedly, we rarely use GE breakers and mistakenly assumed from the pics the unused disconnect took a "main" only breaker. This is why we didn't think a line side connection was possible.

So just to clarify, we can snap a THQL 60A solar breaker on the top disconnect for a true LINE SIDE connection and avoid dealing with a sub panel and any load side rules, correct?

Check the panel label, but yes.

 

[ggunn]

In the proposed configuration, there are two separate service disconnects. The equipment manufacturer has installed dual lugs (or the equivalent) on the load side of the meter, and brought one set of factory conductors to the main breaker with distribution panel below it that has already been populated in the photo. The other set of factory conductors goes to that small 2 position bus at the top of the enclosure that is currently unused.

Ah, I didn't see that. Never mind.

 

[BackCountry]

Is that Nevada specific? AFAIK in California if you're on an shared transformer and the system is under 30kW they can force you to wait for the upgrade, but not to pay for it.

Is that Nevada specific? AFAIK in California if you're on an shared transformer and the system is under 30kW they can force you to wait for the upgrade, but not to pay for it.

If it’s shared, then it’s different. If it’s a single customer on a transformer you’re screwed.

 

[ING23]

I just want to thank everyone who took their time to reply and drop some light to the solution. As soon as I learn to post photos here, I'll post the result with the new Breaker. Thanks again