I am STUMPED!!!HELP ME !! (please)

[ptonsparky]

Bad neutrals will not create any higher voltage than the applied line to line volts. Most likely somewete in between. When younhave the time and the smoke is already gone put two volt meters on a service. Different leg to neutral. As you load up the panel with 120 v loads one meter will increase in voltage as the other goes down. 80 v on one meter should give you about 160 on the other. That is loose or bad neutral. If one meter drops and the other changes very little or not at all it is your ungrounded conductor or connection.

 

[Strife]

Bad POCO transformer.
The transformer can still give you the voltage, but it can't handle the load. So you basically get a voltage drop. Try this: Get a 12VDC inverter and hook it to two 9V batteries. Then try to turn on just one light bulb at 100W.
Without load the inverter will show you 120V, but as soon as you turn on the light the voltage will drop. obviously 2-9V batteries can not handle 100W so the voltage will drop.
Strangely enough though, I have ran into this problem several times in the last year, whereas before I maybe have seen in it once every two years.

I have been an electrical contractor for 8 years, in the business for almost 20 yrs, today I got stumped. I have a 120/240 v single phase panel, there is a 2 pole main breaker on the top of the panel. When I turn on one of the branch breakers, the a phase of the main breaker drops to 20 volts. I spent hours troubleshooting this and I cant get a grasp on what is happenening. When I turn the branch breaker back off, I get 120 v on the a phase, lwt me know what you think before I quit the business and become a plumber!

 

[weressl]

Bad/broken neutral is my first guess.

So what would happen if the 'wrong' leg is grounded in the panel? X1, X2(center tap), X3 and either X1 or X2 is bought back from the transformer with a WHITE wire, no bonding at the transformer only in the panel.