Had one of those - "Oh my word, I'm doing it too?" moments yesturday. In my own head I turned a standard practice (Not installing 3-phase in resi) into a non-existant code in my own mind. I've torn apart the code looking for something that isn't there. (Or was it, or is it. and I can't find it????) Self-realization of hypocritical practice is a bummer. (That practice being creating non-existant codes.)
Mark Heller "Well - I oughta....." -Jackie Gleason
In my hometown (Oradell NJ) there's a few 50's era high end houses that are fed 3 phase power. Looks to be open deltas with a wild leg (240V center tapped grounded, and 208 to the wild leg). Yhese high end houses must have had central air built in as new, and back then the units must have required 3 phase power. Once went to a garage sale at one of these houses, and I saw a main panel, and what probably was a subpanel for the rest of the house (non air conditioning 120V loads). I suppose one could connect an electric dryer using the wild leg, if you're careful to make sure the 120V motor does in fact get the 120V line and the other end of the 240V heater element gets the wild leg. Probably not code, though...
Had only one three phase home in the city. Mansion built in the 1920's. 240V, 400 amp. Remember 1920's. They installed the three phase because it had an elevator and air conditioning. They demolished it last year to make room for a McMansion that has yet to be built. Alan-- Now it is common to see 400 and 600 amp single phase on houses, mostly because the POCO won't supply three phase.