panel board installation, fed by two main breakers

[wish-i-knew-more]

hello,

I have a customer that wants to install a new subpanel into a solar system. They are designing it so that both the 90 breakers in the main 200 amp panel are feeding power into either side of the new 225 amp sub panel buss bar. The sub panel has a 200 amp main breaker that is then connected into the inverter and rest of the solar system. Can you guys help me understand why this would be permitted? I looked up the installation instructions for the new sub panel and it does not show a scenario like this. I wish I could post a screen shot but the forum won't let me.

 

[jaggedben]

hello,

I have a customer that wants to install a new subpanel into a solar system.

I'm going to assume you mean install the solar system into the new subpanel.

They are designing it so that both the 90 breakers in the main 200 amp panel are feeding power into either side of the new 225 amp sub panel buss bar. The sub panel has a 200 amp main breaker that is then connected into the inverter and rest of the solar system. Can you guys help me understand why this would be permitted? I looked up the installation instructions for the new sub panel and it does not show a scenario like this. I wish I could post a screen shot but the forum won't let me.

I'm having trouble picturing it (especially the 'either side' part) but it sounds like illegally parallelling conductors, especially if they are less than 1/0.

If the point is just to connect the solar system, why not do a new panel with only one of the feeders? What else is going in the new subpanel?

Also some panels would have the option to replace the two 90s with a single 200A breaker (or 175A, or whatever).

 

[wish-i-knew-more]

I'm going to assume you mean install the solar system into the new subpanel.



I'm having trouble picturing it (especially the 'either side' part) but it sounds like illegally parallelling conductors, especially if they are less than 1/0.

If the point is just to connect the solar system, why not do a new panel with only one of the feeders? What else is going in the new subpanel?

Also some panels would have the option to replace the two 90s with a single 200A breaker (or 175A, or whatever).

I found a way to post a picture. Hope it works. I'm not sure what the point of this is. I don't always get to know. I can't find any specific language to deny or approve this with.

After the main panel is tied into the sub panel, it goes to the inverter


https://postimg.cc/zHgjSCJ5

 

[jaggedben]

Yeah that's nuts. It's also a violation of 240.8.

I gather they are wanting to do whole-home backup with a 200A device that you haven't shown. Otherwise it makes no sense at all. But if they can't get a 200A breaker into the main panel then they need to do a service upgrade, or not backup the whole home, or something else.

 

[wish-i-knew-more]

Yeah that's nuts. It's also a violation of 240.8.

I gather they are wanting to do whole-home backup with a 200A device that you haven't shown. Otherwise it makes no sense at all. But if they can't get a 200A breaker into the main panel then they need to do a service upgrade, or not backup the whole home, or something else.

Thanks! I was stuck in 408.

 

[LarryFine]

 

[Fred B]

Sounds like they are attempting to parallel the conductors. Here is a simpler solution to feed through and can get to a full 200A and only one set of wire.

 

[jaggedben]

Sounds like they are attempting to parallel the conductors. Here is a simpler solution to feed through and can get to a full 200A and only one set of wire.
View attachment 2572718

Looks like a picture of a 125A lug set. Not sure how you see that working here.