Each circuit is capable of using the breaker amperage, however it is not
likely that you would use all the amperage for *every* circuit at the same
time. Therefore the main breaker should be less than the sum of all the
breakers.

Note that a lot of people are now getting a 200 amp main service and
breaker when upgrading. It is not that much more expensive for a 200 amp
service -vs- a 150 amp service.

So will you ever need a 200 amp service or will 150 amps do?

Add up the amperage of everything you will use at the same time, plus
anything you may purchase in the future.

Thanksgiving is a good time to use lots of electricity.
Stove and all burners on, microwave, dishwasher, maybe washing machine too.
TV, stereo, all lighting, electric heating going full blast because kids
running in/out constantly, etc. Hot water heater going. Friends visiting
and have RV plugged in...

If you have gas heating and water heater, there will be less of a load, so
150 amps may be plenty.

For future.. Will you get RV? Arc welder? Air compressor?



"KEN ANKELE" wrote in message
We are having a new home built and the breaker boxes have just been
installed and I am unsure about a couple of things. We have a main
breaker
box outside the house and a sub-panel in the garage.

The breaker in the main panel for the sub-panel in the garage is 120A.
All
the breakers in the garage sub-panel add up to around 400A. So, the
maximum
I can draw at a time through the sub-panel is 120A. Is there a rule of
thumb
for the ratio of sub-panel breakers to the main breaker for the whole
subpanel??

Same deal for the outside main panel. The main breaker is 150A, but all
the
"sub-breakers" add up to almost 400A.

Are these numbers anything to worry about??