Well, I'm in a position of wanting to go whole-hog ($$$$), and desperately needing to get some 240v electricity to the garage to run my Unisaw (because I don't have $$$).
I'm pretty much dead in the water for any major project until I get some power to run it. I also need to make some storm windows for the house before winter gets here... But it's not a drop-dead priority.
Anyway... I got curious about the existing wiring and I opened the junction box on the left side of the garage and I found this:
The garage currently features a single switched 15-amp circuit (interior lights, motion sensor exterior light, single interior GFCI outlet, and garage door opener) plus a second three-way circuit to turn off the exterior lights from the back porch of the house.
There are 6 wires in there, they all seem to be marked "THWN" three appear to be 12 gauge, 3 appear to be 14 gauge.
Couldn't the 12 gauge theoretically carry 240v? I don't care about the three-way switch lights, so there's a line for the 15 amps I can use to supply the existing lights and opener. Eventually, I'll build some manual tri-fold doors, so the garage opener isn't going to stay indefinitely, either. I really only care about turning on lights and power tools out there.
Could I make this work with the existing wiring - a 15 amp 110v circuit and a 20 amp, 240v circuit? For the time being only, *not* as my permanent shop power solution. Not as ideal or as convenient as a proper service box, but it'd get me moving again. Crazy idea?
I also dug around a little bit on the web and found a 2005 article from Popular Woodworking (issue #150, October 2005) about wiring up split 240/110 circuits. It was written by an electrical engineer and specifically stated that it was (at the time) code-compliant to chain 110v plugs off your 240v run. it looked legit (and published in a major magazine)
Is anyone familiar with this approach?