We're getting ready to build a detached garage/ADU about 100' from our main house, and have a quick question about getting power out to the building.
We currently have a 320amp service to the main house, with two 200amp panels (Siemens model S4080B1200A). Initially I wanted to use a 150amp plug on breaker and run 2/0 out to the garage, however looking at the sticker on the panel it looks like the max breaker size I can use is 100 amps.
However looking at the approved accessories for the panel, it lists Siemens ECLK2125 and ECLK2225 for subfeed lugs.
So looking at NEC 240.21 if I'm reading it correctly, I can use the sub feed lug kit to tap off my main panel, run power out the garage, and use a sub panel with a main breaker?
If i do it this way, do I need to size the wire for the 320 amp service coming to the house, or can I still use the wire sized for 150 amp?
My other option would be to use say two 75 amp circuits and two subpanels out in the garage/ADU. Id rather not do that as it will double up my costs for wire/conduit and panels but if using the sub feed lugs isn't an option, it seems like that may be my only bet.