One additional measurement you should take to nail this as a bad neutral connection is the voltage from L1 to L2.

When you see the imbalance between L1 / neutral and L2 / neutral see if L1 to L2 is also wandering. I expect it is fairly constant, and this nails it down as an unconnected neutral issue.

I had this in my house. We noticed it by our lights flashing when the load changed. I did not get good AC measurements as my meter took that day to go south. We have a friend at the local utility co and he got a tech out that day. Problem was at the power pole due to a fallen branch the year before.

 

Problem found and fixed! The connection from the utility side neutral and the bar on our side was loose and corroded. Thank you all for your responses and help!

 

Whose cage did you rattle? How you got the problem fixed and who discovered it, is just as important?

 

There were two boxes that we couldn't touch on the utility side and at this point we told them we'd open tomorrow morning if they weren't here. They called that night and were here first thing in the morning.

Measuring utility side and our side showed immediately the connection problem. The environment is pretty harsh on electronics here in Hawaii.

 

connection from the utility side neutral

Nya nya...told ya' so.

 

I agree. This smells like a bad neutral wire. The symptom which points to this is one side of the power line voltage rising in voltage instead of declining when a load is attached.

Bad neutral wire can cause a fire.
The neutral return line is damaged then the voltage of each hot line can swing WAY out of tolerance and that can cause devices on the high leg to consume more power, burn out, flame out or just die early.