DIYbanter - View Single Post - Load capacity of 200-amp panel

Smitty Two

In article ,
(Doug Miller) wrote:

In article
,
wrote:

Consider this simple circuit analogy which is exactly what you would
have with a balanced load on a 240V service. It's a 240V voltage
source powering two 120ohm resistors.

____________ 240V___________
I I
I I
I I
---------120ohm---------120ohm---------
a b c

There is only 1 amp of actual current flowing in the circuit. Across
each resistor there is 120Volts and 1 amp of current flowing. So,
yes you have 1 amp flowing in EACH load, it is supporting two 1 amp
loads, but it's the same physical current flowing through each load.
The "service" is only supplying 1 amp of actual current, not 2.

What voltage do you measure between a and b? Between c and b?
What current do you measure between a and b? Between c and b?

*Immediately* above your two questions, he answered them both, Doug.
There isn't really so much disagreement going on, it's just that y'all
aren't paying attention to what the others are saying.

That's what I meant when I said a 200 amp service cannot supply 400
amps of current.

But it can. 200A at 120V on each leg is a total of 400A at 120V. The two legs
of a residential electrical service are, in effect, two parallel circuits.
200A flowing in each of two parallel circuits is 400A total, not 200A.

Consider a house with only 120V loads, no 240V circuits anywhere, and 200A
service. Suppose that one leg of the service is fully loaded, and the other
leg is unloaded. I think we'd both agree that the power being drawn is 200A
at
120V, right?

Now fully load the other leg too.