I went on a service call yesterday. In a store downtown, a lady had a 250 watt metal halide light that would trip off then come back on. The breaker never trips, only the light. It would do this once, maybe twice a day, sometimes not at all. It is a fairly new fixture, isn't in a location where it would build up excessive heat and it is a 250w ballast.
The outlet that it is plugged into was originally a 220 outlet converted to a 110. Whoever had worked on it previously had used one of the hots and the ground as a neutral. Our fix was to use the other hot as a neutral and yes, we did go to every jbox we could trace and mark it neutral. Would using the ground as a neutral cause the light to trip? If not, what else?