My mother. 92 and a bit senile has been putting 100w incandecent light bulbs into 60w fittings. After a few days the bulbs burn out. She asked where she was going wrong! As soon as she switched on the lights the bulb burned out and the switch in the fuse box switched to OFF and she replaced it with another 100w!. I replaced the 100w bulbs with 60w ones. How likely is it that she has done permanent damage to the light fitting and the electrics?