w_tom wrote:

Do incandescent bulbs dim or brighten when larger appliances start or
stop?

FLOATING NEUTRAL !!!

If there is a LARGE fluctuation between L1 and L2 and the Neutral Buss,
at the fuse Panel, this would indicate a poorly grounded Neutral on the
Power Pole, a Service Provider problem. or at the fuse panel, a
Customer Problem.

There are rarely Power Surges on domestic power lines except during
Thunder storms ! The so-called surges most people see are Voltage
fluctuation due to un-balanced loads made worse by a bad Neutral
Connection . The incoming 220 does not fluctuate, but due to the to a
bad Neutral connection, the potential between L1 and Neutral and L2 and
Neutral will swing badly with the load. This occurs most often with
Aluminum Wiring, and the cure is to tweek the Ground Straps once in a while.

The incandescent bulbs are the "Poor man's Voltmeter". if you were sure
that the two bulbs in question were on opposite legs of L1 and L2, one
would brighten as the other would dim. There would only be a slight
change in the total Voltage, so not really a "Power Surge" ! Just an
INTERMITTANT noisy connection at the Neutral Buss.

Yukio YANO