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Q.I'm doing some wood siding repairs on a house, and every time I hit the trigger on my chop saw, the lights in the house flicker. The power company says the problem is with the house not their lines. But the lights in the house across the street flicker, too. A friend suggested that there could be a bad connection on the neutral. How can I determine what the problem is, and get the power company to fix it if it's their responsibility?

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 particular tap.

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 with.

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 house.

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.