1. Wires are twisted to cancel out differential mode noise. Not all
multiconductor phone cables are twisted pair. Always buy the ones that
are labelled for multi-line, they are twisted. It really sucks to run
a bunch of cable all around carrying 2 lines in it and find out you
can hear the person on the other phone. Happened to me years ago.
2. Ground fault breakers have neutral connected to them and then
neutral for circuit connects to the breaker along with the black wire
on the hot terminal. Reason is that the ground fault breaker needs to
monitor the hot to neutral voltage of the circuit and the most
accurate way to do that is by monitoring the individual neutral wire
for the circuit.
3. Power = Volts x amps (already stated). Other forms of the equation
for inductive or capacitive loads and 3 phase.
4. Yes, all electrical wires have some amount, however small, of
inductive and capacitive component. For electrical power, the
inductance is only an issue with frequencies greater then 60 hz. I
remember the days of wiring 400hz motor generators for computer
systems. The wires had to be derated for the 400 hz and you had to run
them in aluminum conduit because the inductive reactance of the 400 hz
in a steel conduit would cause the conductors to heat up. Steel is a
good shielding material and it keeps the fields within the conduit
much better then aluminum, therefore the fields heating up the wire.
So, a great thread in some ways. Wow, all this theory and we still
haven't figured out what the author's issue is.