SER cable ampacity

C

caddyking951

Member
Location
Corona, CA
Good morning, I am installing a 200amp 120/240v critical load sub panel in a home that we are remodeling. The main service is 400amps. Solar is being installed with batteries to back up the 200amp panel. What size copper ser cable is needed for the 200amp panel if they will be spraying foam insulation in the ceilings encapsulating the ser cable. I have dug through the nec but there are a lot of variables. I live in southern California
 
California is currently using the 2020 NEC (I believe the 2023 NEC goes into effect January 1). For the 2020 NEC, 338.10(B)(4) only imposes a 60C ampacity limitation on SER with #10 and smaller conductors in contact with thermal insulation. So you may use the 75C ampacity for your conductor sizing. Which for 200A for Cu conductors means 3/0, as 310.12 does not apply to your scenario (edit: assuming no derating applies).

Cheers, Wayne
 
Eddie702 said:
I guess the make copper SER but I havent seen copper SEU or SER in 50 years.
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Definitely not stocked around my area. Would never choose it over AL for residential feeders. $$$ and heavy.

My supplier does special order 666 CU SEU cable for me for 60 amp EV charger use.
 
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