arcing

Hi all, I have just moved into a house and went to use the light switch last night, it buzzed then shorted. Took the switch off this morning and there looks to have been an arc across to neutral(?) This switch has 2 feeds, looking at it the right switch controls the downstairs hall, the left...

So I am in the process of getting one of the rooms in my house re-plasterd after it had damp remedial work done to it. Today I took down the existing light fitting that was in the room (was a wooden based 3 x ses swivel light with 3 x 5w SES LED candle bulbs) and I replaced it with a normal BC...