I have a 4mm cable from my main consumer unit to my garage. It runs from one side of the house to the other through the loft space, to a garage style consumer unit. I was using a 550 watt pillar drill in my garage and the power went off. I checked the MCB on the garage consumer unit and all was ok, but no voltage and nothing tripped. I checked the MCB on the main consumer unit and that was fine. There is voltage from the main consumer MCB and using a NCV along the cable I get a reading and suddenly it stops? Seems strange that theres a break in the cable all of a sudden? It's never been touched or damaged ?