When it rains, one of our breakers sometimes opens... probably caused by a short circuit due to water ingress.

Unfortunately, that breaker also protects our gate motor... which is not fun to deal with when it's raining. The most likely circuit to cause the problem is the lights on our outside fence. There are about 9 LED lights on that circuit. The breaker only opens during/after rain.

I'd prefer not having to crawl into the attic to trace the electric circuits and isolate them. I can manage inspecting each of the lights for a potential problem.

Is there a simple method to test that the fence lighting circuit is the problem? I was thinking to install a low value inline fuse that would blow when a short occurs. If the fault is located in a different circuit on the breaker, I assume that fuse would not blow. Is that possible/effective?

If that circuit is guilty.. other than inspection, how to identify which light fixture is to blame? Having never been tested, I'm not convinced my inspection abilities would be adequate.

I have no experience dealing with wiring issues... is my thinking sound?

If the lights and gate are both on the same breaker, are they not on the same circuit?

Are the LED fixtures for exterior use?

Is the cover for the motor watertight

You could disconnect the motor and see if the problem goes away. If it does not, hook it back up and unhook the lights one at a time.

Is the wire underground?

Wait for some dry days and on three separate days aim a hosepipe at each to see if you can initiate an open breaker. Once you have isolated the cause you can delve a bit deeper.

55 minutes ago, Yellowtail said:

If the lights and gate are both on the same breaker, are they not on the same circuit?

Are the LED fixtures for exterior use?

Is the cover for the motor watertight

You could disconnect the motor and see if the problem goes away. If it does not, hook it back up and unhook the lights one at a time.

Is the wire underground?

I call the light circuits as separate because there are 4 switches controlling different sections... of course all sections lose power when breaker opens

the gate motor... no switch but dormant until activated by remote or wall button

not sure if bulbs are for outdoor use, but are enclosed in a fixture which while not waterproof should protect them from normal rain... maybe not protected if rain comes with strong wind

we never have a problem with gate motor during rain unless due to breaker opening... but I understand that since no power flows until motor is activated so that doesn't rule it out as the source. I am fairly certain the breaker doesn't open until the lights/gate motor draw power because I have a smart home relay powered by the same breaker and it remains online until breaker opens.

wire is underground from garage to gate motor area then from there it is split to fence lights and motor.... so that's a potential problem area

all the fence lights are on one two-wire loop, but since the problem is intermittent I would have to do the testing after failure brought on by rain or as @VocalNeal suggested I make my own rain after some dry days

Edited yesterday at 11:19 AM1 day by gamb00ler

Is the breaker that is opening a simple MCB or an RCD/RCBO (has a Test button)?

It certainly sounds like water or creature ingress. Try removing any accessible covers and check for damp or wildlife. Start with the easy ones!

It's the underground plastic conduit flooding when it rains, and shorting out a twist join (wrapped in insulation tape) the installers used in the middle of the conduit, cos they measured the underground wire wrong, and were too cheap to do it again with a single wire run.

That's always the reason.

You ain't gonna fix it without replacing the complete underground wire run.

I have the same problem, but it's the gate lights. And the conduit runs under the concrete driveway.

Edited 16 hours ago16 hr by BritManToo

1 hour ago, BritManToo said:

And the conduit runs under the concrete driveway.

Our driveway also certainly covers the buried conduit.

I am lucky that I can check the status of the breaker just by looking at one of my interior light switches because it has an LED that indicates if it has power or not. That switch is also on the same breaker.

I also just realized that I have an alternate and unused switched circuit I could use to replace the current circuit powering the fence lights. That circuit is for a light to shine on the house number plaque and the switch is right next to the one for the fence lights. No light fixture installed yet.

3 hours ago, Crossy said:

Is the breaker that is opening a simple MCB or an RCD/RCBO (has a Test button)?

It certainly sounds like water or creature ingress. Try removing any accessible covers and check for damp or wildlife. Start with the easy ones!

It's a simple MCB unit. After the rainy season... I'll use the garden hose to see if I can find the guilty connection.