Hello my name is Mark and I have just purchased my first home. I was hoping someone could help me out in determining what size feeder cable I would need to run from my main panel to a detached garage. The length of the run would be 70 feet. The main panel is a 100 amp panel. I would be running 6 shop lights, a handful of 15 amp outlets, and 2 spotlights. I would also like to have room for a little expansion room if need be. Thanks in advance for your help.

-Mark

Without knowing the loads of what will be in the shop, and not wanting to overload the 100 amp main panel, I would suggest using #8 Romex cable, 3 wire with a ground, on a 40 amp breaker in the main panel, and an 8 circuit panel in the garage.

This may not be enough expansion, but without knowing the connected load of the home, may want to be a bit conservative.

There is nothing wrong with installing a 100 amp feeder to a 100 amp subpanel in the garage. The 100 amp main breaker to the home will limit how much is used for both the home and garage. Will depend on how much is used at the same time in the home and garage.

Thank you very much for your quick response, I really appreciate it. That was just the type of answer I was hoping for. I would rather be safe and conservative then anything else. Thanks again!