I have 240 supply coming from my supplier. 3 wires 120 volts , 120 volts, and neutral. As soon as I turn on my breaker one of the 120 line goes low to something like 65 volts and the other lines goes high to 170 volts. Why is that?

How are you taking you voltage measurements?

Help us a little, please.

By supplier, do you mean the electric utility company? Are you measuring the voltage at a main service panelboard in a residence?


Have you contacted the power company to have them verify the connections and the supply side of their equipment?

Have you shut all of the breakers off in the panelboard and then turned the main breaker on so that you can see if any one particular branch circuit is causing the problem?

This type of imbalance is typically a loose neutral problem...
Before you damage anything call an electrician...