I was recently called to a flat (only built 5 years ago) where the lighting MCB constantly tripped.
The first picture shows the heat damaged cable I found behind each of the 34 GU10 down lights. They had been stuffed into the ceiling cavity, completely surrounded by insulation with the cable packed on top of the fitting.
I ended up rewiring the entire light circuit and fitting heat proof flex and 20a junction box, after removing bags of insulation!
