A bit hard to see because of the location, but this photo shows a problem we found at a client’s house today. The hall light hadn’t worked since they moved in and some tests revealed a cable fault between the switch and the light.
We then spotted someone had drilled a hole in the very top corner of the wall near the switch. A bit of digging revealed the unlucky driller had put a 7mm hole straight through the centre of the cable!
One junction box, some cable and half an hour later the lights were back on – all of them!