If I feed a 100a main lug panel with say a 40a dp breaker, do I have 40a total capacity? Or do I have 40a available on each leg for 120v loads?
Russell,
Look at it this way--
40A @ 240V = 9600 VA
and
9600 VA/120V = 80A
So, you've got 40A on each of the legs.
Cliff
If you touch each of the two little screw heads on the circuit breaker where the wires go with the test leads of a voltmeter and it says 208 or 240, you have 80 amps of 120 volt power available. That's assuming you have a neutral too. Of course.
(signed) Sorry. I forgot my name.