Investigation of short circuit during rain

Presumably, it might be enough to measure the cables individually with a multimeter set to resistance measurement with the fuse turned off, L against PE. Otherwise, you can also borrow a device to measure the insulation resistance. Of course, only a professional should do this...

The layperson stands there in flip-flops and pours water over the lamp where they suspect a short circuit. Sometimes you really have to wonder whether these are serious tips or satire.