I think I found the info that clears up my understanding of a 240 circuit:
Quote:
Now for the quick explanation of 240 / 220 volt house current; Appliances which use straight 240 current (such as electric water heaters, or rotary phase converters) also have three wires:
1) A black wire which is often known as the "hot" wire, which carries the current in to the fixture.
2) Another "hot" wire which may be blue, red or white (if it is white the code actually requires it to painted or otherwise marked one of the other colors, but often it is not) which also carries current in to the fixture.
3) A bare copper wire called the ground, the sole function of which is to enhance user safety.
That's it, no neutral. Now, if you are paying attention, then you are probably wondering "If there isn't a neutral wire then how is the circuit completed?" The answer is that when one hot wire is negative, then the other is positive, so the two hot wires complete the circuit together because they are "out of phase". This is why 240 volt circuits connect to double pole breakers that are essentially two single pole breakers tied together. In the main panel, every other breaker is out of phase with the adjoining breakers. So, in essence 240 volt wiring is powered by 2 - 120 volt hot wires that are 180 degrees out of phase.
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So by the above, I should put one hot wire to the twisted pair shown in the picture, and one to the switch which would complete the circuit. The ground is then tied to the chassis, the screw in the back of the terminal box.
Is that right? If so, then the P.O. didn't have a ground wire to the motor chassis.