I recently began experiencing overvoltage and undervoltage fluctuations in my home. And as a result, I have lost two small televisions and a computer monitor. I'm also unable to run any motor loads such as the refrigerator, washing machine or vacuum cleaner. I also have trouble with loads such as a toaster or even an iron .
Under noload conditions, with all branch breakers off, I'm measuring
240V L-L and 120V both L-N and L-G at the main. Both line and load side of the main breaker have the same readings.With loads on the system, readings range from 80 to 160 volts L-N depending on the loads.
The utility came out when I was not at home and checked their lines when all loads were off, not even a clock was plugged-in (absolute noload conditions) and declared everything on their end to be fine. They will not return and also said it is not their problem. They suggest I "check my breakers." My house is served from a tap on an overhead 240V line which also serves other homes. From the line tap to my meter the utility says everthing is OK.
I have therefore deduced based on the symtoms I am experiencing that I likely may have a problem with a neutral conductor(s).
Can someone recommend a systemic approach to troubleshooting this problem so that I can isolate the affected branch circuit(s). Please be detailed and technical. For example, if I need to lift each branch circuit from the breaker and megger it to determine the resistance L-N and L-G, etc. then I will rent a megger. Do not suggest that I "check my breakers" because they have not tripped.
Thanks