I have a light in the hall that does not work. Whoever put it up seems to have put a screw through a wire, if you try to use it it trips the circuit board. We also have a extractor fan in an ensuite which doesnt work and I suspect dodgy wiring here too. We have had a number of instances of bad wiring that we are fixing as we go. We do have an rcd circuit breaker so it isnt that it is old wiring just bad diy by previous owners.