I installed a new light fitting approximately a year ago, which had a long flex. I shortened the flex by cutting both wires, and rejoining them with chock blocks which are contained within the ceiling rose of the fitting. Six months on, the light was not working. So I checked the rose connections, and found one of the 4 terminals on the chock block had burnt and melted. No fuse tripped, the light just stopped working. Could this be the screw in block was not screwed down onto bare wire, leaving the wire to arc a connection until the connection was lost? None of the other connections looked burnt. I have replaced again, trying to ensure screws are screwed down onto wires and not the insulated sleeve.