"zeno" wrote
Hi Jack,

So could I light up a 100 watt light bulb with one terminal stuck in the
earth
out in the middle of a field and the other to the hot side of an AC
circuit?...I guess so.

Bill,
Just before it blew up, it would light up, yes. Remember I said "With a
properly resistive load" and that would be a very dangerous however possible
experiment to attempt. The circuit breakers are set to prevent your
haphazard determination of what current load is too much - the hot wire
supply in should be matched with "cooler" (neutral) return, accounting for
acceptable current usage by the load... up to the point where too much
current generated heat trips the breaker. Nothing forces you (in your
experiment) from keeping all of that available voltage (0v felt on neutral)
as long as the current did not exceed 15a or whatever your breaker allows.
Obviously a 100w light bulb shorted to ground would blow instantly, before
the breaker could protect it..


The Earth is the ultimate return path I guess. The neutral as I understand
it
is the center tap of the high voltage step down transformer which takes
two hot
leads from the high voltage line and steps it down to 240V with a center
tap
being the "neutral". The neutral is then grounded for extra safety. The
neutral
(center tap) does not need to be grounded to provide the return path, but
what
my question is why the Earth per se is also a return path? I guess being
such a
large mass it is theoretically a zero potential.

Would my theoretical light bulb get brighter as I drove the rod deeper
into the
earth?

Assuming a series of (18) 100w bulbs on a 15a circuit (120v), yes the ground
rod's resistance (5-15 ohm depending on soil) would allow less than the full
brightness of the bulbs, until or if you were able to reduce the impedance
by using a larger surface area rod and drive it deeper into wet soil. This
is the same principle of making the very best and lowest impedance ground
system you possibly can for lightning protection!

73's

Jack



Bill K6TAJ

Jack Painter wrote:

"zeno" wrote
Oddly enough this circuit only used the hot side of the AC
outlet and a cold water pipe ground to the chassis of the
transmitter. Our house was built in the early 40s if that
tells you anything about how they wired outlets in those
days.

My question:
If I were to take a volt (amp) meter and put one probe in the
hot side of an AC house outlet and the other probe to a metal
rod stuck in the ground out in the middle of a field
somewhere (presumably nowhere near a neutral leg), what would
my meter read and why?
Deep electro-philosophical answers welcome as long as it is
expressed in terms a child could understand. (It seems that
this little odd transmitter circuit avoided the neutral leg
altogether-- just used the hot side and a ground).
Bill K6TAJ

Hi Bill,

Ground is referenced at both the generating station and your home in
order
to complete the circuit. In your home's service mains panel, ground and
neutral are bonded together. Before the days of the third wire, added
purely
for safety in the event of an equipment fault, a faulted piece of
equipment
still had a return path, just not the added measure we have today of a
very
short ground path (no pun intended) G

With a properly resistive load you could still perform your field
exercise,
but it would have nothing to do with avoiding a nearby neutral wire
which
serves the same function anyway. Neutral was always and still is, the
return
path of a parallel circuit, nothing more or less. It is cold when no
load is
connected to it and hot (minus the resistance-consumed current of a load
applied) when a load is connected.

73's

Jack
Virginia Beach, VA