- Be sure there is no fault in the UPS, or conduction from neutral or hot to local ground of any metal.
- Remove the ground pin's connection to the generator from the UPS only with a cheater.
- Do not ground the UPS or anything connected to it referenced to the generator's ground.
Alternatively, de-bond a bonded-neutral generator and ground the generator's ground to Earth ground. Once debonded, a generator has to be treated differently and always grounded.