You’re an electrician for a commercial/light industrial electrical services firm. A restaurant contacted your firm about a collection of possibly related problems that started a few weeks ago. Every so often, someone complains about a “weird tingling sensation” while working at one of the stainless steel kitchen counters. Two people reported getting a nasty shock when grabbing the handle on one of the freezers. And there’s been a rash of equipment problems during this period. Three of the commercial microwave ovens stopped working. Most of the problems have been in the kitchen, but the office has also been experiencing equipment problems.
Where do you start?
Get an equipment history. Find out when each item was installed, and when it was last serviced. This may help you quickly pinpoint the equipment that most contributes to the problem.
For example, “A few months back, we added that small dishwasher because the big commercial one doesn’t have the capacity for Friday nights.” You’ve probably got a BINGO moment here.
If this approach reveals a problem, that doesn’t mean you found “the” problem. At a minimum, inspect the wiring connections on each piece of equipment and test the integrity of the conductors (e.g., conduct insulation resistance tests).
Then inspect the service panel for proper grounding, bonding, and neutral connections.
