"Nate" writes:
"Jeffrey J. Kosowsky"
5. Making existing 100A panel into a subpanel of the new panel and
connecting to new panel. I believe this involves separating the
grounds from commons on the subpanel and adding a 100A breaker to
the new main panel.

Half assed shortcut, IMO. Rip out the old panel, stick in a new one with
modern hardware and breakers. This should be no big deal. By leaving your
old panel in place, he's saving a lot of time - time that it sounds like
he's quoting you anyway! Further, you just paid 3 freak'n grand and you're
still stuck with a bunch of (100 year?) old gear.

Good question.
The current 100A panel is in good shape and by its looks is no more
than about 20 years old.

In general I would agree about ripping out the old, I am just not sure
it will gain me much.

The current panel if full with 30 circuits. The biggest panel we can
put in is 42 circuits.

We are planning on adding 2-3 central AC units plus adding a number of
new circuits to fill in around the house (it's a big house and many of
the rooms have only one outlet which in some cases is ungrounded, so
we are going to fill in with new circuits).

Though I would aesthetically prefer it all in one box, my concern is
that if we consolidate it all into one box, we will be left with very
little space for expansion.

What would you recommend?