I have a technical question someone can please help me I have a 1 inch conduit with 4-120 volt 20 amp circuit s .and 2-240volt 20 amp circuits. my question is how many grounds do I need please state NEC.article numbers

Can someone help me with STRAY VOLTAGE--I manage a Military Base overseas and have all power comig from generators. We have isssue with equipment, usually PLCs getting burned up, the modules along with othe line voltage equipment etc... We've checked all the grounding at the X-Fer switches and at the MDPs, the distribution equipment, the sub panels and at the generators and can not seem to stop it. Any advise would be greatly appreciated. Jerry Fletcher/Kosovo/CBS