Intermittent Tripping of an Exterior outlet powering lights

[SFSam]

I recently bought a house that has an old ( only one button that pops out when the circuit is tripped, no test button) gfci outdoor recpectacle installed. From that receptacle are light switches for a swimming pool, a gazebo and garden flood lighting. The configuration on the flood lights is Receptacle ----Fixture ------ Fixture. On the other side from the receptacle are the 3 switches. The pool light has 1/2 of the box and is installed vertically. The floodlights and gazebo share the other 1/2 of the box and are mounted horizontally with the flood light switch above the gazebo light switch.
At times all 3 lights work, but at other times the receptacle GFCI switch pops disabling the pool and floodlights. The gazebo light always works. They will all work one night and then not the next. Or the pool and floodlights will be working and then trip, they are always on or off together. It is often days or weeks later until it works again. I have not be able to discern a pattern.

Does anybody know what may be causing this? And can you point me to where to look to repair the fault.

Thanks,
Sam

 

[bernardgreen]

The most likely cause is water getting into on or more of the light units.

This water will create a path between the hot wire and earth that will create a ground fault and trip the gfci when the light is turned on. The fault will remain until the water dries out which could be several days. The fitting may have been damaged by corrosion.

If it is not water in a light fitting it could be a damaged cable in damp ground or similar.

 

[SFSam]

Thanks for your prompt reply. That was my suspicion as well. I have a tendency to think it at the receptacle itself since the rubber gasket has fallen off, and even though this is the dry season, the sprinkler system could be the culprit. I rather tend to think it is not the pool light, since that is an underwater light. If that is the case, why would the pool light and the floodlights trip and not the gazebo light?
Since the gasket is missing, I think it would be prudent to replace that receptacle and then see if that resolves the problem, or is that a backdoor approach to the problem?

Thanks again,
Sam