A new electrical problem surfaced yesterday and I wanted to air it here to get your views before I take issue.
A light bulb in a ceiling fitting in the loft blew. This is in one of two light fittings on the same circuit. I replaced the bad bulb and switched on the wall switch. The was slight click and neither fitting lit up. I went to the consumer unit and turned off the supply on the circuit for the lights in the loft. I came back up and to be safe, I put a voltage detector to the fitting and was surprised to hear it beep. I toggled the light switch and in both positions and the detector still registered voltage.
I thought then that maybe the circuit was mis-labeled. I then turned off various circuits and found that the voltage disappeared only when the circuit for the 13 amp sockets in the loft and the loft lighting circuit were both turned off at the same time.
I kept the circuit for the sockets off then put two new bulbs in the light fittings. I switched on the wall switch. Only one came on. The original bad one was still not working.
I'm not an expert in electrics but something here just isn't right - to put it mildly.
What should I do next to check things and to try to get to the bottom of the mystery?