[brianl703]

Power companies don't follow the NEC. They follow the NESC, which has different rules. Since the customer is typicallyresponsible for the wiring to the meter, that does need to be sized for 400A per the NEC tables.

However, the power company can size the service drop conductors (which they, not the customer, are responsible for) between the meter and the transformer for the expected load, not the size of the main breaker.

It is apparently pretty common for the service drop conductors to be smaller than the service entrance conductors.

I was just reading of several cases where people with 400A services that actually use most of it had to call the power company due to low voltage problems or in one case tripping a breaker at the transformer. The power company had to take the appropriate steps to solve the problem--a case where they estimated the load to be lower than it actually was.

[from occupied ga]

If you go over what the standard residential load for your area is - usually 200A - you can be charged a demand charge as well.