I replaced the photocell on an exterior lamp, removed the fixture and connected it to an outlet on the same outside circuit and it burned for 4-5 hours with no issue.
Then I removed 2 of the three Cree low wattage bulbs and the one remaining bulb tripped the circuit breaker after a few hours.
I thought if there is a problem with the underground power cable it would trip quickly, not after an hour or so. What could be causing it to trip in this manner?
I will note that this is an old fixture and the problem appears to be getting worse.