Greetings,
I have a 200amp service in the house and a separate 200amp service to my detached garage/shop. The power utility is charging me a rate 3x's higher on the garage than what they charge me on the house. I want to cancel the 200amp service to the garage and have the utility company pull the meter. Then I want to connect a 100amp sub-panel to the house.
Currently, there is a buried 2-2-2-4 USE AL cable (Southwire mobile home feeder) connecting the garage and the basement of the house.
The USE cable in both the basement and the garage won't reach the power panels because it is TOO SHORT.
1.) In the basement, I'm planning to install a 2-2-2-4 SER cable to a 100amp circuit breaker in the 200amp Load Center. I need 60' to get to the other side of the basement where it will be spliced to the USE cable in the splice box using a power block or split bolts.
2.) In the garage, the USE enters through the cement slab protected by a 2' PVC conduit. I want to connect the USE to the SER extension cable in a 100amp unfused electrical disconnect.
3.) Then, I want to connect the 100 amp disconnect to a 100amp main lug which will serve the branch circuits in the garage/shop.
4.) Lastly, I will need to route the branch circuits from the decommissioned 200amp garage panel through a short 2' connecting conduit to the adjacent 100amp main lug panel.
Parts I have:
1. 100amp General Electric 32753 Indoor Main Breaker Load Center: I want to remove the 100amp circuit breaker and install main lugs. NEC says I can't have the same amperage protection on the feeder. I would have to make it less than 100amps. The next size down is what, 60amps. If I use a main lug panel, I can stay with 100amps.
2. Used Square D FUSED 100amp disconnect; I would like to jumper the fuse holders for the same reason given above.
3. Hoffman fiberglass enclosure 18x16x10 RHJ1816HWPL2LG: to use for the splice box in the basement. It should be adequate to splice the (3) 2awg & (1) 4awg AL wires.
4. If the power utility pulls the meter on the 200amp panel in the garage: Do I need to remove the 200amp circuit breaker and/or the meter pan before I convert it into a junction box? I would like to have the option of converting it back to the separate 200amp service if circumstances change.
Thanks for any suggestions,
Mark

Do not jump out the fuses, install 60 amp fuses in the disconnect, or get a non fused disconnect.

Yes you can use the old panel as a junction box, be sure to close any openings, to include screw the door closed.

Otherwise your plan is fine.