Incidents of equipment failure have increased noticeably over the past year. A review of maintenance department records shows a rise from historic levels in purchases of motors, lamps, ballasts, circuit boards, control modules, circuit breakers, and branch circuit distribution transformers. Nuisance circuit breaker trips have also increased, though the load measurements almost never show more than about 70% load on a given breaker. What are some first steps toward solving this problem?
You are probably dealing with a systemic power quality problem with multiple causes that have gotten worse with time. Over the past year, the proverbial chickens have come home to roost.
To stop the failures, you must use a methodical approach to locate and repair their cause(s). Begin at the source, which in this case will be your service transformer(s). If your company owns these, you'll probably need to hire a firm with expertise in transformer testing and analysis. If the electric utility owns these, you'll have to work with them. This will likely still mean engaging an outside testing firm.
Working your way in from the service toward the branch circuits, conduct cabling tests, grounding and bonding conformance inspections, and thermographic imaging to identify and fix problems.