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Re: Need help powering my garage - long
I will start with the 6-3. It means #6 wire and three conductors. It will not include the ground usually. You will need four conductors for 220 V red, black, white and green. Buy the wire that has #6 in the black, white and red. Green can be smaller. You will need #6 for a 50 Amp feed. White is neutral, red goes to one 110 V leg the Black goes to the other 110 V leg. Green is ground. It is called 220 V because of the 110+110=220. Either side voltage to ground will be 110 V. I absolutely do not recommend 100-amp service. You will need to use #2 wire at least.
The easiest will be to make a "drop cord" like Ozark says. The drop cord should use range plugs and not dryer plugs. Dryer plugs are rated at 30 amps, range plugs are 40 amps. Closer to 50 amps but I will caution you later about this. Put a male range plug on the "Inside the house" side and a female range receptacle on the "Outside the house" side. This is for safety. What if somebody who doesn't know how your contraption works, unplugs the male garage end first, drops the exposed plug on his leg and gets a real shocking wake up call!!
I would mount a 50 Amp (or 40 amp-explain later) Load Center on a ply wood board; mount your receptacles each on its own breaker. For the incoming from the load center I would put on a male range plug, plug it into the female outlet when needed. I would mount 4 20-amp breakers, 4 20-amp outlets. Garage outlets are supposed to be GFCI outlets. It sucks for some things but thatís code. Wire the outlets with number 12 wire. White goes to the side with the big plug(silver on the outlet screws), black to the hot side (brass screws on outlet) and green to the frame (green screw)of the outlet. I would also add one 220 V female outlet on the board for your air compressor etc. This is a long run for 110V loads and is hard on the compressor motor.
Now my cautions. Again, dryer outlet=30 amps and range outlet=40 amps. If you have these already in your house, the wire to these is rated to handle 30 or 40 amps, not 50 amps like your garage board is designed for. The wires in the house may overheat and cause the fire. The weakest link thing... You have to make sure the whole circuit can handle 50 amps. If not, only go the 40 amps with the range stuff and number 8 wires. This should be enough for your garage.
Hope you understand this. Buy good wire-I recommend SO type wire, flexible, tough, made for this type of use but expensive. But....paying for dead people and burnt houses is too.
By the way...legal stuff since I am a Professional Electrical Engineer. I recommend a permanent installation to the local codes and the NEC, and not this temporary thing.