Had a job to look at yesterday concerning the kitchen lighting. Lady said that one row of downlights had stopped working. The lights were controlled by two single mounted dimmer switches so Maybe one of the switches had packed up? The lights were GU10 that wasn't working and selv on the cluster that was working. I switched of the mcb for the circuit concerned and one of the drops to the switches was still live!! ( Good job for safe isolation procedure ) I found that when I switched off the 32a sockets mcb the feed to the switch was dead ( this was the selv cluster) I got the row of dowlighters that was proper to the app 6a mcb working and proved that circuit to be healthy. The lady said that the lights had been fine in the time that She'd been at the house so I explained about how much current the cable can carry and fault conditions and that further investigation was needed. I made safe the ends of the conductors and put a blanking plate on for safety.She is getting me back to do and EICR on her property soon as she is now concerned about what else is lurking.