I’m troubleshooting an in-ground pool light that burns out within 5 seconds of turning it on. The old light burned out like this the first time I turned it on this year. The old fixture was shot, so I replaced it with a new one and the bulb burned out within five seconds. Water is not leaking into new fixture.
I disconnected the feed wire from the fixture wire and read 125V at the feed wire, about as expected. I then isolated the hot and neutral wires by disconnecting them at the breaker box (about 66 feet away, cable running underground) but the ground wire is still connected. A continuity check between the disconnected hot leg and neutral or ground wires shows minute continuity (about 5,000 ohms resistance). Is that normal? If not, would a small leak to ground like that cause a light bulb to burn out?
The light bulb is 500 watts on a 20 amp circuit with a GFCI circuit breaker. The breaker never trips and the GFCI test function operates normally.
I’ve checked and ensured no loose connections at all wire connection points (including switches) from the breaker to the fixture and I find no evidence of arcing or overheating at those points. The circuit is wired with two three-way switches. Nothing else is on the circuit but the 500 watt bulb.
If nothing else I’ve reported here would burn out bulbs without tripping the breaker, then what else could the problem be? Thanks, Rich