Big Giant Head wrote:
On branch circuits the size of the wire and type of circuit determines the
breaker size but what determines the size of the main or combination of
mains? Can it be as large as the panel is rated for or must it match the
size of the utility's drop?

We have an old panel with two mains, one is a double 50A feeding the rest
of the panel. The other is a double 30A feeding the dryer outlet directly.
The town now mandates 100A and I think homes get inspected when sold.
Rather than replace the whole panel I could replace main #1 with a double
70A (if available) OR maybe better would be to replace main #2 with a
double 50A (or higher) and have it feed a small subpanel in which I would
put a double 30A for the dryer and maybe throw in a few others as well.
That's within the rating of the main panel but not sure about the utility
drop.



The maximum size mains are determined by the box rating, or the size of
the service conductors, or the rating of the meter, whichever of these
is smallest (very rarely is it the meter.)

The 100A minimum requirement shouldn't apply to you *if* an electrician
does a load analysis and your service is large enough (look up the terms
"ex post facto law" and "grandfathered")

Bob