Re: 60 Amp Sub Panel in Attached Garage
My scenario was nearly identical to John's.
I bought a 100amp rated panel by Siemens, but the panel is fed by a 60amp breaker in the main panel. The main feed wire to the sub-panel is armored 1/2 only because I had a deal I couldn't refuse. It runs through a basement/garage wall, coming out just above the garage's foundation wall, and then, surface mounted to the panel which is mounted at a height specified by the book. The inspector told me 6/2 would have been just fine.
Since stud spacing didn't work for me, I attached 1/2" plywood to the studs and the sub-panel to the plywood. All connections and wires are neatly run and clearly marked. That includes labels on actual outlets.
All wiring from the sub-panel is 12/2.
I installed the following outlets, each on a separate circuit:
110V, 15 Amp * 1 (lights and a quart heater)
110V, 20 Amp * 2 (portable power tools)
220V, 15 Amp * 2 (DC and TS)
All wall mounted wires are in metal conduits, 1/2"
Things I would have done differently:
1. 20amp breakers for 220v, instead of 15amp
2. use one or two space saver breakers, instead of regular 2-pole ones for 220V, because I have now one space left, but need two
As for the 60amp feed to the sub-panel, I see no reason to go higher, unless welding is in the cards. I met a woodworking pro with an impressive workshop and he said his shop is wired with 60 amps.
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