Are lug's code compliant on this DIY 175A breaker panel? Needed for 10KW PV system

[jaggedben]

For a 10kW max system, a 60A disconnect fused at 45A or a 45A MCCB would suffice. Other details would present themselves, such as where and how to tap the service conductors.

If the system is 10kW AC at 240V, it will require a 60A OCPD, due to PV being considered a continuous load.

Unfortuantely AHJ does not permit line side taps for residential.

That is such BS. Do they allow it for the other purposes explicitly permitted by the NEC? AHJs need to get over it. I realize my saying all this doesn't help you.

I thought this would be a very common situation with a common solution? I guess not.

Yeah, the common solution is the line side tap! Or the breaker downsizing.

There are a lot of 200A homes out there. Do most of you PV installers just recommend 7.1KW max systems so you dont' have to mess with this?

I think most installers would try to present two options, the one that requires the upgrade and the one that does not. And do their homework on the supply-side connection option before giving the quote.

I would install a 200 amp fusible disconnect with 175 amp fuses as the service disconnect and connect the load side of the new disconnect to the line side of the 200 amp breaker in the panel. You will also have to relocate the main bonding jumper to the new disconnect and separate the EGCs and neutrals at the existing panel.

This would probably be the cheapest, simplest solution, if the AHJ won't allow a supply side connection.

 

[Smart $]

For a 10kW max system, a 60A disconnect fused at 45A or a 45A MCCB would suffice. Other details would present themselves, such as where and how to tap the service conductors.

If the system is 10kW AC at 240V, it will require a 60A OCPD, due to PV being considered a continuous load.

I realized that after I posted, but also after OP'er replied saying AHJ doesn't permit line-side taps. Figured correcting my statement wasn't worth bothering.

That is such BS. ... AHJs need to get over it. I realize my saying all this doesn't help you.

Yeah, the common solution is the line side tap! ...

My sentiments exactly.

 

[fmtjfw]

Sounds like a good reason to go to the supply house before wasting time chasing basic parts on Google.

The guy at my supply house can get me virtually any breaker of any make up to 600A & 600V within a week, often within 48 hours.

 

[Zee]

superduperdude,

If i consider the fundamental problem to be how to connect a 10 kw pv system to a 200 Amp panel with minimum expense - and in a Code-compliant fashion:

Pls. consider a 8 KW inverter. If made by SMA (good idea in any case) its cont. rated AC current is actually only 32A. (It should be 33.333)
That was specifically done to allow use of a 40A brkr. (not 45, 50 or 60)
40 A vs 200 A Main = 120% rule met.

True, 10 kw pv array vs an 8 kw inverter is on the high side for pv array to inverter ratio.
BUt install 9.6 KW of panels.
That gives you a 1.2 ratio. In my area that is the upper limit of good system design.
It is, however, an excellent option for 10 KW of DC power on a 200 A main.
Hell, considering that usually you will see 2/3 of the dc rating in output, you can even put in 10 KW.

1. Code does not prevent you.
2. Real world doesn't either: On those rare days and moments that the pv is capable of more power than the inverter, the inverter will just clip it to max 32 A. No danger of overload.

(ps you didn't ask, and you probably know, but ensure PV breaker is landed opposite feed in Main
Both Code, and safety considerations, require it

pss if you really want to be pro, ensure inverter is in shady, cool spot. It will be operating closer to its peak on a more regular basis. It will be hotter more often. Heat is a major inverter killer. Fans or no. Fans can and do fail on these guys, to boot.)

If, on the other hand, you meant 10 kw AC system, then...... what those guys said! )

 

[superduperenergydude]

"ensure PV breaker is landed opposite feed in Main
Both Code, and safety considerations, require it"

Yes the inverters are going to be inside and breakers located very far away from main panel in a sub panel.

 

[jaggedben]

"ensure PV breaker is landed opposite feed in Main
Both Code, and safety considerations, require it"

Yes the inverters are going to be inside and breakers located very far away from main panel in a sub panel.

Regardless of whether the breakers are located in a subpanel, the PV backfeed needs to be located opposite the main feed in all panels. See 705.12(D)(7).

 

[superduperenergydude]

qrn vs qn breakers

qrn vs qn breakers

So the exsisting main breaker is a siemens/ITE qrn series 200amp
a guy i called said there is a ITE qn2175 breaker that would work
however looking the data sheet below, it looks like qrn are horizontal and qn series are vertical.
However, when you look at the product names on this same data sheet there are NONE named qrn. that's confusing. does anyone know differences between qrn and qn series?

http://w3.usa.siemens.com/powerdist...t-catalog/Documents/sf-11-sect-01-038-039.pdf

 

[Smart $]

So the exsisting main breaker is a siemens/ITE qrn series 200amp
a guy i called said there is a ITE qn2175 breaker that would work
however looking the data sheet below, it looks like qrn are horizontal and qn series are vertical.
However, when you look at the product names on this same data sheet there are NONE named qrn. that's confusing. does anyone know differences between qrn and qn series?

http://w3.usa.siemens.com/powerdist...t-catalog/Documents/sf-11-sect-01-038-039.pdf

As noted...

[Note 5] QNR required for horizontal applications or vertical
applications where the lugs are facing up. The QN
breaker is required for vertical applications where the
lugs are facing down as shown.

 

[superduperenergydude]

"

Originally Posted by George Stolz Sounds like a good reason to go to the supply house before wasting time chasing basic parts on Google.
The guy at my supply house can get me virtually any breaker of any make up to 600A & 600V within a week, often within 48 hours."

I went to 4 supply houses before someone who had been working in the trade for years came up with almost the exact part I needed. NONE of the 4 supply houses knew of 175amp siemens breaker. Had 3 of them tell me it didnot exsist. The GE breaker 175A was also not available until I pulled it out of my box and showed them.
ONE place even sold sunny boy and solar panels.

And in the end it was me searching the internet getting the exact part number that I needed and telling the supply store what to order. qn2175R

the "r" at the end of the nomenclature is what confused me.

I appreciate the help on the forum none the less.

so basically the advice you give is only good if you have knowledgeable sellers.

I probably took 10 hours or more finding this solution, but popping out a breaker and putting in a new one will be easy and obvioulsy be code compliant.

 

[kbsparky]

Sounds like a good reason to go to the supply house before wasting time chasing basic parts on Google.

In my experience these days, I can find it quicker, get it quicker and for less $$$ than the supply houses.

Case in point:

I needed a EHB24020 breaker. None of the supply houses had one. One of them said they could get it from a broker. For about $400. Rest of`em said SOL.

I found one brand new on ebay for less than $150. Took 2 days to get it here. `Nuff said.

 

[electrofelon]

A couple comments: What is the busbar rating of your panel? Unless I am missing something, why not A) swap out the panel for one with a 225 Amp bus or B) what about putting in a more normal sized main breaker like a 150? Also I would ask the AHJ for their local code amendment that prohibits tapping service conductors in dwelling units....

 

[jaggedben]

A couple comments: What is the busbar rating of your panel?

He said in the first post it's 200A.

Unless I am missing something, why not A) swap out the panel for one with a 225 Amp bus

Because he's looking for a simpler and/or cheaper solution. And because a 225A panel may not be much easier to find than a 175A breaker.

or B) what about putting in a more normal sized main breaker like a 150?

He hasn't mentioned if he's done a load analysis, but a 150A breaker might be too small.

Also I would ask the AHJ for their local code amendment that prohibits tapping service conductors in dwelling units....

Agreed.

 

[Zee]

Super duper,

Are you looking for confirmation/validation of your approach...........or a solution?
I put considerable effort into thinking about a solution. You did not address it or reply or even express an opinion.

Is it 10 kw AC or DC???????????????

 

[electrofelon]

Maybe Im wrong, but I thought most modern "200A" panels had a 225 bus? I think with QO stuff that is the case. Yes an easy solution is always nice but I wonder how much time he has into looking around for that 175? Seems like quite a bit from the OP. I mean come on I can swap a panel in a few hours or less (yes this approach would be contingent upon my theory that a 200 main bus panel is readily accessible). Of course I know nothing about the house and loads, but we all know you cant get 95% of houses above 80 or 90 amps with everything on. Just seems like this is being made way too complicated....Sup Duper: let us know how you are making out

 

[jaggedben]

Maybe Im wrong, but I thought most modern "200A" panels had a 225 bus?

That would be a contradiction in terms: a 200A panel has a 200A bus by definition. If you mean that many panels are sold with 225A busses and pre-installed 200A main breakers, maybe that is so, although my experience does not match that. I've seen many panels with 125A busses and 100A breakers, but on most 200A panels I've seen that's the rating of both the bus and the breaker.

 

[electrofelon]

Jaggenben,

I dont see why the main breaker rating has to match the bus rating. They are two different things. If I am reading the square d catalog correctly, all homeline and QO load centers with factory installed main breakers from 150 to 225 amp all have a 225 rated bus. I cannot speak for any brands.

 

[electrofelon]

OK I concede you never said the main breaker has to match the bus rating, looks like I made that up. You said "panel". I guess if someone says "200 amp panel" I would say that is a vague term, depending on the context

 

[Uprising1928]

200 amp bus with 175 amp breaker kit.

200 amp bus with 175 amp breaker kit.

I installed a 200 amp main lug Square D panel with a 200 amp bus rating and bought a 175 amp breaker kit for it. The whole deal cost around $275 dollars. The breaker took a couple minutes to put in. This allowed for a larger than 40 amp breaker and even a little extra for future expansion. Hope this helps.

 

[jaggedben]

You said "panel". I guess if someone says "200 amp panel" I would say that is a vague term, depending on the context

I don't really agree. When the NEC refers to the "rating of a panelboard" it is most definitely talking about the rating of the bus. Sure, depending on context and who is talking, it may be important to clarify both the bus and the breaker ratings. But there is a correct answer here as to what the word "panel" should refer to, and it is the bus.

 

[Smart $]

I don't really agree. When the NEC refers to the "rating of a panelboard" it is most definitely talking about the rating of the bus. Sure, depending on context and who is talking, it may be important to clarify both the bus and the breaker ratings. But there is a correct answer here as to what the word "panel" should refer to, and it is the bus.

The pertinent requirement says nothing about panel rating.

(2) Bus or Conductor Rating. The sum of the ampere ratings
of overcurrent devices in circuits supplying power to a
busbar or conductor shall not exceed 120 percent of the rating
of the busbar or conductor.

Here's one that I'm going to guess is overlooked at times...

(A) Supply Side. An electric power production source shall
be permitted to be connected to the supply side of the service
disconnecting means as permitted in 230.82(6). The sum of
the ratings of all overcurrent devices connected to power production
sources shall not exceed the rating of the service.