I had an emergency call yesterday. The homeowner was having trouble with dimming lights (with motor surges---much more than normal)and a gas dryer with electronic controls wouldn't start.
I was getting voltage readings within norm, when the POCO guy came. I told him I suspected a neutral problem. He put the phases under load, which showed an imbalance. He said anytime a voltage reading in single phase varies more than 4 volts (L1-N, L2-N)it's probably a faulty neutral.
The homeowner asked why the lights dimmed and he described the current flow in a sine wave with a faulty neutral (using his finger on the wall). Not exactly something I'd try with a homeowner.
Anyway, can anyone explain this clearly or show a diagram of how this changes the current flow? He seemed to be saying that since the neutral was faulty the current came back on itself causing the lights to dim and brighten.
Dave
