Can I backfeed this old Cutler Hammer 100A main panel?

[ogdento]

I would like to backfeed this older Cutler Hammer 100A main panel with a 2.4kW solar system that will be on a shed 25' away, and I'd like to ask if anybody knows what model panel this is, or sees any code issue with backfeeding the solar to it.

I can't find much identifying information on the panel itself - the main breaker is 100A, and the sticker on the back of the user-operable cover is not readable. My plan was to mount (and bolt down, per backfeeding requirements) a 20A double-pole breaker in the 2 lower right locations. That 20A breaker will feed the sub-panel in my shed where the solar will be connected to a 15A dp breaker (also bolted down) in a new Eaton sub-panel.

two notes:
1. I know a new 200A panel would be better. We eventually want to upgrade to 200A and move the main panel to the side of the house but time isn't on our side... we'll need to make some significant structural changes first, and solar rates in California are changing this April.
2. I know the panel must be re-labeled... that blue tape was from me trying to figure out wtf the previous owner did.

Thanks for any input!

 

[AntonLargiader]

Any idea what year it's from? Post a complete pic, preferably with the cover or deadfront off.

Having recently been involved with an old CH panel, I can say that the modern breakers will fit the old panel but I don't know if there is a bolt-down system for it.

 

[Norcal]

No way to add a hold down to a older panel & based on the C-H sticker on the dead front, I would say that is a early 1960's model those panels used a main breaker that 4 spots were taken on both sides of the interior and the hold down was attached to the breaker, but close to 30 years later that a hold down requirement for backfed plug in breakers was added to the NEC.

Those old panels were built like a brick schiff house.

 

[ogdento]

awww **** that's going to be a huge bummer if I can't use a hold down in there... would a CH125RB part not work (if I drill a hole for the screw)? https://www.cooper-electric.com/product/detail/25780/cutler-hammer-eaton-ch125rb

Here's a picture with the dead front off... even though it's old as heck it's got a nice thick copper bus bar. And you can see what norcal was talking about with the 4-spot main. but wow, this thing might be from the 60s?!

 

[ogdento]

 

[AntonLargiader]

Looks a lot like my dad's '60s panel but he has a separate MB.

That hold-down is an interesting device. If there's room for it between the metal rail and the plastic bus holder, I don't see why it wouldn't work.

 

[ogdento]

Thanks @AntonLargiader, and @Norcal for identifying the "era" when this thing was built

I couldn't remember where I read about drilling your own hole but last night I found it in the Home Depot reviews... I'm not an electrician and I don't know if code prohibits drilling, so I'm hoping it's a legitimate option

Reviews for Eaton CH Breaker Retainer Bracket | Pg 1 - The Home Depot

Read page 1 of our customer reviews for more information on the Eaton CH Breaker Retainer Bracket.

www.homedepot.com

 

[ipgenie]

When I installed solar, they required a home run from the solar inverter to the disconnect at the main panel next to the meter. Connecting to a sub on a shed was not allowed. They want to be able to switch it off while standing at the main.

They also required the bus rating to match any combined sources. If the bus is rated at 200A and the main breaker is 200A, the main would need to be replaced by a lower rated breaker allowing capacity for the rated production of solar so the solar and utility sources combined would not exceed 200A.

I upgraded my meter panel to 400A and used one side for the solar system and the other for the rest. I didn't want to drop my main to 125A.

 

[ogdento]

When I installed solar, they required a home run from the solar inverter to the disconnect at the main panel next to the meter. Connecting to a sub on a shed was not allowed. They want to be able to switch it off while standing at the main.

They also required the bus rating to match any combined sources. If the bus is rated at 200A and the main breaker is 200A, the main would need to be replaced by a lower rated breaker allowing capacity for the rated production of solar so the solar and utility sources combined would not exceed 200A.

I upgraded my meter panel to 400A and used one side for the solar system and the other for the rest. I didn't want to drop my main to 125A.

how long ago did you did you install solar? I would have thought the 120% rule would have let you add a (max) 40A backfed breaker to your existing 200A panel (since 20% of 200 is 40)

interesting bit about not allowing a solar connection to a sub-panel... I didn't know that was disallowed. I could stand at the main and shut off the whole sub (which would have the solar and the original single shed circuit).

 

[ipgenie]

I installed it in 2020 in Idaho so there may be different requirements. Mine is a larger system so 40 wouldn't be enough. The meter combo I had would have allowed two 40A solar breakers but I would still have had to reduce the main for my system (a 40 and 3 35s). I believe a tap would be another option but I didn't look into the details on that.