Jim Beaver wrote:

I've got a newly-built house (well, actually, it's 2/3 new, 1/3 existing)
with new wiring from the panel in. It's got a 200 amp rating at the
panel. But whenever the air conditioning comes on, the lights dim and
power dips much more than I've ever seen in another house, even ones with
lower amps
and older wiring. Sometimes it's enough to shut down my computer or TV.

The wire coming in from the pole is what was here when only the existing
house was here. How likely is it that a problem like this is on the
city's side of the breaker panel?

Jim Beaver
You might want to verify the various wire connections in the panel are tight
and well connected (but only if you are comfortable with things electrical)
A bad connection will cause a voltage drop under load.
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By any chance... are you using Aluminum wire? If so, i highly recommend you
rip it all out and get what you can for scrap price out of it. AL is ok in
very large sizes (as long as its correctly installed with proper torque and
an anti-oxidant on good clean connections), oh say above 00 but even still,
I'd go all copper if i possibly could.
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I really doubt its a utility transformer problem, but I'll bet dimes to
donuts its either a bad main breaker or a bad connection in your panel,
either at the mains, the meter or one of the bus bars in the panel.
Eric