"bill a" writes:

i'm curious why you are running the 200a SE cable so far inside the
house. my guess is that you are doing the new entrance in a different
location than where the old service was, and you will be putting the
new panel where the old one was, in order to reconnect branch circuits.
if so, you might consider putting the new panel just inside the
building (like normal), and then make a feeder run of #2 or 0,
whatever, over to the old panel. You don't necessarily need 100a
ampacity on this run, as long as the breaker size protects the feeder
wire. Depending on what's in use on the old branch circuits, you may
be able to feed with quite a bit less than 100a.
Then feed new branch circuits out of the new panel.
Just a thought.
Bill

Well, this is the way the old feed went. It enters the house at one
end, goes through a 100A main breaker and then goes about 30 feet to
the other end of the house where the main 100A panel is.

We thought of various alternatives for the upgrade including:
1. Placing panel at entrance and moving all circuits to this new panel
-- however, then we would need to rewire all the branch circuits or
have some type of nasty junction box replacing the old panel

2. Placing a new 200A panel at the entrance and converting the old
panel into a 100A subpanel
-- however, we thought this might confusing and a PITA having the
two panels separated by the length of the house. Especially,
since given the mix of old and new wiring two circuits feeding
the same room could end up in different panels 30 ft away from
each other.

Therefore, we are planning instead to consolidate all the circuits at
the location of the old panel. In doing this we considered two
options:

A. Place new large 200A panel next to the old panel and convert the
old 100A panel into a subpanel of the new panel. This would mean
leaving the bulk of the circuits in the old panel and keeping the
new main panel mostly unpopulated (but likely to fill in over
time).
-- we chose not to do this since this seems a little kludgey with
the subpanel having more circuits than our new main panel

B. Instead, we are planning to replace the old 30 circuit 100A panel
with a new 42 circuit 200A panel in place which requires a bit more
effort to move over the breakers and reattach neutrals and
grounds. Then, we will move the old 100A panel to a location next
to the new 200A panel to hold any circuits after we run out of
space in the new panel.

Finally, rather than having a meter outside, then a main breaker just
inside, and then a 30 ft run over to the panels, we are thinking about
placing a combo meter/breaker unit outside replacing our old meter and
then entering the house and running 30 feet directly over to the new
panel. This has the benefit:
- Reducing costs (since no need for separate main breaker just
inside the house)
- Eliminating "extra" box inside the house
- Allowing fire dept easy access to electrical shutoff in case
of emergency

Does this thinking make sense??

Jeff