John'
You might want to check and see how your neutral was connected in the sub panel if that is where you are making your connection. Normally sub panels do not ground the neutral. If the sub panel neutral is grounded you could have a ground loop problem. Should be easy to try it both ways. Grounding and neutrals is not something the local power company crews are very knowledgable about.
Earl
2003 Silverado SB/EC Dark Green
Duramax/Allison, XM-Radio, Z82,VYU, DPF, UO1, UY2, and NP1. Bed mat, running boards,and 5th-wheel hitch.