A.Master electrician Rex
Cauldwell responds: This has to be a utility
problem: low voltage or too great a load for the
available voltage. There is no other way your chop
saw would be able to affect the house across the
street. Probably both houses are working on the
same transformer, and the transformer is
underpowered. If you are on different transformers,
then the utility really has a problem. It means
that their high-voltage line is overextended -- in
other words, there are too many homes on that
The "bad neutral" theory doesn't add up. A
service entrance connection (SEC) neutral problem
gives a whole set of different problems. Every
house has two energized lines into the house and a
neutral that either hot line can use. When an SEC
neutral goes bad, one of the hot legs to the house
goes high, and the other leg goes low. In the
house, that will likely damage anything connected
to the leg that goes high.
That's not to say that there isn't also a
problem in the house that is making things worse.
For example, if a house is underpowered, that would
tend to make the lights dim more easily to begin
The homeowners should have an electrician check
out the utility problem and verify it; that way the
utility is hearing from a professional that it is
their problem. Here's how I would troubleshoot:
1. With a high-quality digital volt-ohm meter
(VOM), measure the voltage going into the service
panel under load and nonload. Load one leg, then
the other, then both. The voltage should not change
more than a few volts. If it does, the transformer
is too small.
2. Make the same measurements with someone
across the street operating the chop saw. If the
voltage goes down (and we know it will), the
problem is outside the house.
3. Make similar measurements at the utility
meter. If the voltage drop occurs before going into
the house, we know the problem is outside the
4. Look up at the transformer and read the
kilovolt-amp (KVA) rating, which is often painted
on the side. A 200-amp house at 240 volts needs a
45-KVA minimum; with two houses you need twice
that. Odds are, they are running both houses off
one 45-KVA transformer.
I'm confident that the main problem will turn
out to be the power company running too low a
voltage on the primary and overextending the tap
line. I've seen this more times than I can count.
If the utility won't cooperate, the house owner
should write the state utility board, with a copy
going to the utility. Normally the utility has 30
days to respond to the board.