"Steve N." wrote in message
...

"JIMMIE" wrote in message
...
On Oct 26, 10:37 pm, (Doug Miller) wrote:
In article , Sam E
wrote:
If all the loads supplied by that service are 120V loads (e.g. blender,
toaster, light bulbs, range hood, stereo, TV, computer, etc.) what do
you get
when you divide that maximum power by 120V?

That would be 400A.

Exactly so.

Of course that's only in your imagination since
the math is invalid (120V is obtained by splitting the service into 2
separate halves, each of which is only 24KW).

200A each. Total of 400A of 120V loads -- as you said.

Where in the box can you measure 400 amps? If the panel is controlling
48KW there will be no current on the neutral because the currents will
be balanced. The current that flows through one half of the breaker is
the same current that flows through the other half of the breaker. In
this case what you have is two 200 amp breakers in series. Doug you
have more current coming into the box than going out and that shouldnt
happen.

The power is coming in from a transformer secondary winding that is
center-tapped. Let's call the 3 wires
Line 1, the neutral & Line 2 (seee the link below that shows a transformer
secondary at the bottom of the page). When you put 120V loads across Line
1 & neutral, they are independent of Line 2. In effect, you're only using
half of the transformer secondary, so you're only going thru the Line 1
half of the main breaker. The current path is from the Line 1 side of the
secondary winding, thru the Line 1 side of the main breaker, thru the
load, and back thru the neutral to the Line 1 half of the secondary
winding. If you also put a 120V load across Line 2 and the neutral, then
the current path is from the Line 2 side of the secondary winding thru the
Line 2 side of the main breaker, thru the load, and back thru the neutral
(in the opposite direction of current flow of the Line 1 current thru the
neutral) and back to the Line 2 side of the secondary winding. Both loads
form their own circular loops that are independent of each other, except
for sharing the neutral (in opposite directions) to complete their
separate circuits. Here is a great explanation of the transformer
secondary, using the battery analogy which the author (not me) originally
designed to show balanced loads, but is also useful in showing how 120V
loads form independent circuits on each side of the secondary. You can
even close the various switchs and see the effect.

http://home.comcast.net/~ronaldrc/wsb/ax.htm

I need to make a correction - the Line 2 current flow would be down the
neutral, thru the load, up thru the Line 2 half of the breaker, back to the
Line 2 side of the transformer. The currents flow in the same direction thru
the transformer secondary "halves", and in opposite directions thru the
neutral.