Valdemar
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125A Load Center, what are my options?

Sun Aug 25, 2013 6:57 pm

I'm thinking to add solar to my home but my utility company will only allow upgrading to a 125A service panel which is the max that the feed cables can handle. The home has a direct burial feed which can in theory be upgraded but without going into much details let's say it is going to add a significant cost to the project which I'm trying to avoid for obvious reasons. Considering the 120% rule I can only install a ~4Kw array on a 125A panel which will be somewhat undersized for the 2300+ sq. foot home with a pool and an EV to charge daily. I see there are load centers available with side tap which allow to connect solar before the main breaker, but the smallest capacity I can find is 200A. Utility company won't allow to install a 125A main breaker on a 200A panel, their argument is that a future owner can swap the breaker and melt the cables underground. Do 125A load centers with a side-tap exist? Any other options I can consider? Thanks.

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planet4ever
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 7:18 pm

My home has the main breaker installed next to the meter. (That's the way it was when I bought the home more than 30 years ago.) When the company I contracted with installed solar they added a subpanel close to the meter and fed from there through a safety disconnect to the house side of the main breaker. The service panel never sees the solar power directly, only merged with the utility power, and only what is needed to serve the house. The city approved that setup.

Wouldn't it be possible to remove the main breaker from the service panel and put it in a new panel near the meter? I guess conceptually the new panel would become the main panel, and the service distribution panel would be a large subpanel.

Ray
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.

QueenBee
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 7:26 pm

This is not a problem at all. You are misinterpreting what the utility is telling you. They are not saying you can only have a 125amp panel. What you want to do is replace your service panel with a 200 amp panel, then replace the main breaker in it with a 125 amp breaker. For my GE panel this was easy to do but I had to order the main breaker kit online.

Then you'll have lots of room for solar.

Valdemar
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 7:52 pm

QueenBee wrote:This is not a problem at all. You are misinterpreting what the utility is telling you. They are not saying you can only have a 125amp panel. What you want to do is replace your service panel with a 200 amp panel, then replace the main breaker in it with a 125 amp breaker. For my GE panel this was easy to do but I had to order the main breaker kit online.

Then you'll have lots of room for solar.



It would be too easy. They won't allow a 200A panel for the reasons stated above, and they left no room for interpretation.

QueenBee
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 9:31 pm

Valdemar wrote:
QueenBee wrote:This is not a problem at all. You are misinterpreting what the utility is telling you. They are not saying you can only have a 125amp panel. What you want to do is replace your service panel with a 200 amp panel, then replace the main breaker in it with a 125 amp breaker. For my GE panel this was easy to do but I had to order the main breaker kit online.

Then you'll have lots of room for solar.



It would be too easy. They won't allow a 200A panel for the reasons stated above, and they left no room for interpretation.


I'm sorry, that's what I get for replying on my phone and not reading your entire message.

So do they also disallow 125 amp panels that a 200 amp main breaker will fit into?! What if someone puts in a 200 amp breaker, think of the children!

So how did the utility even get involved in that part if the conversation? In my experience the utility and the AHJ are very hands off each others parts. For me my utility insisted I had a 200 amp service even though the gauge of the wire was clearly not what a modern 200 amp service would support. My AHJ was not at all concerned with the size of the utilities wire as long as the meter box and the wire from the meter box were both rated for 200 amps. I ended up not going to 200 amp because it would have required having the utility disconnect power to replace the meter box. Instead we just replaced the wire from the meter to the panel with 125 amp rated and put in the 125 amp breaker. The utility never touched foot inside my house and has no idea what the inside wiring is like.

Ray, your suggestion would still have the same issue but would just move it.

I'd be surprised they would let you do any taps since then a future owner could stop using solar and use the solar panel and use the panel for their grow op.

I've often wondered what lives in a transformer to protect the wiring and this seems to confirm that they leave them unprotected as clearly the answer is a 125 amp fuse on the transformer would avoid this all together.

The funny thing is my 1969 house is it came with a split bus panel. The main breaker was 60 amps but the top of the bus allowed for 4 or 8 half breakers. So you could eaisly add more breakers than the service was rated for. No one cared when I had 30 amp for dryer, 30 amp for old water heater, and new 40 amp for the EVSE and the 60 amp main, all 240 volt.

Do they make 125 amp panels with enough circuits to handle your house? Seems like you might need a sub panel to handle all the circuits.

How big of a system are you thinking? NEC/AHJ might not be happy with such a small main breaker but what about putting a 100 amp main breaker in a 125 amp panel? This would be safe and I doubt your house will ever have above an 80 amp draw. I turned on literally every thing in my entire house and barely got over 50 amp at 240 volt.

Valdemar
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 9:44 pm

planet4ever wrote:My home has the main breaker installed next to the meter. (That's the way it was when I bought the home more than 30 years ago.) When the company I contracted with installed solar they added a subpanel close to the meter and fed from there through a safety disconnect to the house side of the main breaker. The service panel never sees the solar power directly, only merged with the utility power, and only what is needed to serve the house. The city approved that setup.


Are you sure they connected solar to the house side of the main breaker and not to the service side? This doesn't sound right as your panel would then surely see solar current that bypasses the main breaker, added with the service current it can then overload the panel and melt the bus bars without tripping the main breaker under the right conditions.

EDIT: unless your panel is rated high enough to handle max solar and service currents together, sometimes they derate the panel by putting a main breaker with lower amps to ensure that.

planet4ever wrote:Wouldn't it be possible to remove the main breaker from the service panel and put it in a new panel near the meter? I guess conceptually the new panel would become the main panel, and the service distribution panel would be a large subpanel.


In my case it is an integrated flush panel that has the meter, main breaker, and the rest of the stuff in one box. You can't really go inside and tap in before the main breaker as far as I understand, at least not without violating the code. The service wires are coming from under the house, then through the wall to the panel, so the replacement panel will also have to be of the flush type according to my electrician. There are "solar-ready" service panels that have this tap connector between the meter and the main breaker installed by the manufacturer but I cannot find ones rated less than 200A.

QueenBee
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 10:08 pm

Valdemar wrote:
In my case it is an integrated flush panel that has the meter, main breaker, and the rest of the stuff in one box. You can't really go inside and tap in before the main breaker as far as I understand, at least not without violating the code. The service wires are coming from under the house, then through the wall to the panel, so the replacement panel will also have to be of the flush type according to my electrician. There are "solar-ready" service panels that have this tap connector between the meter and the main breaker installed by the manufacturer but I cannot find ones rated less than 200A.


Do they make a panel like that which has only room for just the 125 amp breaker?

Then you could install a 200 amp main lug panel next to it and run all the house loads and solar loads through that. This gets you increased bus rating without increasing the size of the main service panel.

wwhitney
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 10:29 pm

Valdemar wrote:I'm thinking to add solar to my home but my utility company will only allow upgrading to a 125A service panel which is the max that the feed cables can handle. The home has a direct burial feed which can in theory be upgraded but without going into much details let's say it is going to add a significant cost to the project which I'm trying to avoid for obvious reasons. Considering the 120% rule I can only install a ~4Kw array on a 125A panel

What's your present main breaker?

As far as the NEC goes, you can put in a 125A service panel with a smaller main breaker, say 100A, then the 120% rule would allow you to use (120% * 125 - 100) = 50A for a solar breaker. Of course, since your POCO won't allow a 200A panel with a 125A main breaker, they might not go for a 125A panel with a 100A main breaker.

I have a 125A meter main on my house, Cutler-Hammer WMB1224SCN. It has room for just two (double pole) breakers, of which one is a main breaker for the house and the other is a solar breaker. There's no electrical reason that you couldn't put a 125A main breaker for the house and a 125A solar breaker in such a panel; as long as the solar is never a load, you can't overload the panel. But I'm not sure if the NEC recognizes that the 120% rule doesn't need to be enforced in this situation.

Cheers, Wayne

Valdemar
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 10:58 pm

QueenBee wrote:So do they also disallow 125 amp panels that a 200 amp main breaker will fit into?! What if someone puts in a 200 amp breaker, think of the children!


They don't, or they don't care. If someone does it and home burns it won't be their problem, the fault will be clearly on the homeowners part. However if someone stays within the panel ampacity but burns underground cables and possibly the transformer, then at the very minimum it becomes their problem for repairs and possibly legal consequences if there is any damage to the property and worst case injuries or deaths as it is no longer all black and white as in the former case.

QueenBee wrote:So how did the utility even get involved in that part if the conversation?


Utility had to sign off on the panel upgrade which would be necessary to install solar.

QueenBee wrote:The funny thing is my 1969 house is it came with a split bus panel. The main breaker was 60 amps but the top of the bus allowed for 4 or 8 half breakers. So you could eaisly add more breakers than the service was rated for. No one cared when I had 30 amp for dryer, 30 amp for old water heater, and new 40 amp for the EVSE and the 60 amp main, all 240 volt.


There is no safety issue with having the sum of all individual breakers exceed the rating of the main breaker. As far as I understand it is fairly typical. The worst that can happen is your main breaker trips if you load several circuits at the same time, no harm is done.


QueenBee wrote:
Do they make 125 amp panels with enough circuits to handle your house? Seems like you might need a sub panel to handle all the circuits.

How big of a system are you thinking? NEC/AHJ might not be happy with such a small main breaker but what about putting a 100 amp main breaker in a 125 amp panel? This would be safe and I doubt your house will ever have above an 80 amp draw. I turned on literally every thing in my entire house and barely got over 50 amp at 240 volt.


I've just realized that I may have misinterpreted what my electrician told me or he made a mistake. He said I can have a 4kW system with the 125A panel. Thinking about it, per the NEC's 120% rule I can back feed 25A of solar to a 125A panel with 125A breajer which translates to a 6kW array on 240V. Putting in a 100A breaker on the same panel would give me a total of 50A of solar current which is a 12kW array. I was shooting for a 7.2kW system, so I might be ok with a 100A breaker. Am I missing something?

Valdemar
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Re: 125A Load Center, what are my options?

Sun Aug 25, 2013 11:19 pm

wwhitney wrote:What's your present main breaker?


I have an old 100A Zinsco panel.

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