If you guys are still using mains sets of lights, one of the handiest tools you can have is one of them Volt-Sticks, used for ball-park fault-finding/voltage detection.
A break in the wire is easily found.
Speaking of Xmas lights installs, I'm going to make a point of getting a picture of an elderly couples house from a little town called Chertsey, north of here.
The guy is like 75, his wife is 81 and to be honest, I don't know how he finds the energy to put all them lights up.
He re-invents his install every year.
It is a sight to behold, I'll keep you posted.
