Changing lights in alcove in, these lights are controlled by a pull switch. Disconnected one light, put loose wires in a connector block, tested continuity, it was ok, checked with power on had 240 volts. Removed the second light and checked as before (continuity) this time had a dc voltage reading, same with the other light. Switched off pull switch, again checked continuity with meter, it had switched back to ac, pull on switch and it goes back to dc. All I’ve done is disconnect the wires, any idea why it should do this. The house has recently had a new box fitted by an electrician so I can’t see a problem with polarity, having said that the lights where working ok before is disconnected them,could the pull switch for some reason just become faulty.