I've done that too. I have a bank of 12 metal oxide varisitors. I forgot what each one is rated at, but they are big. They won't clamp until much higher volt

I've done that too. I have a bank of 12 metal oxide varisitors. I forgot what each one is rated at, but they are big. They won't clamp until much higher voltage though. The double conversion UPS is between that sloppy power and the sensitive equipment. Prior to that, I lost 3 UPS units.