We went to see a client today, who’s electricity went off every time it rained – following some minor building work.
Turned out the “builder” had drilled through an underground cable, bodged a repair with a connector & some tape, then buried it and said nothing!
You can see how “waterproof” and safe it was, after the tape had fallen off, revealing the problem.
 

 
We had to use a special epoxy underground jointing kit. The second photo shows the repair before we re-buried the cable and replaced the surface material.