JBD,
The NEC definition of "voltage to ground" says that if the circuit does not have a ground then you look at the voltage between any two of the ungrounded conductors.
it actually says
for ungrounded circuits, the greatest voltage between the given conductor and any other conductor of the circuit.
So with a two wire ungrounded 240 V circuit what is the greatest voltage between the two conductors? It is the same voltage if you measure A-B, B-C, or C-A.
So, with that being the case we would have to consider how much voltage is dropped at the center of a 240 V circuit from each phase of the circuit, and that would be 120 V
Roger
[This message has been edited by Roger (edited 11-03-2006).]
