My 120 volt VFD powers a 1 hp motor. Apparently lightning took it out. The tech guy at Teco said I need to protect it from spikes in both the hot and neutral lines (L1 and L2) but not the ground. He said a surge protector will only break L1 and a UPS will do no better. Best thing is to unplug the 120 volt power when not in use. Too much trouble.
So in discussing with my brother the electrician we came up with a better plan. Install a double pole relay that is on when the shop lights are on. The double pole will break both lines. Since I am only in the shop about 20 hours a week the survival odds are much better. It's still a lump of hardware to buy and install somewhere.
Any better ideas?