"Jeff" wrote in message
...
Yes it may be somewhat confusing. As Einstein (100 years ago last month)
said, it's all relative. Try to picture an oscillating wave representing
120VAC. The difference between the top and bottom of the waves is 120 V.
Now if we force one side to be grounded the other side must be oscillating
between plus 120 V and minus 120 V. But remember there never is more than
120 V relative to ground.

No, not quite. Single phase oscillates between 169 positive peak and 169
volts negative peak, not 120 Volts. This yields the effective voltage of 120
volts (RMS). RMS voltage is .707 x peak. Peak is 1.414 x RMS.

Bob