But where is the MCB? Can I borrow a cup of electrons? Make that a bucket.

[adiewadie247]

I was replacing a light fitting in a ground floor flat yesterday and went to the consumer unit and switched the two M6 MCBs off. The light stayed on. OK I thought maybe they wired it into the sockets.... Switched off the two M32s. Hmm the light is still on. OK lets turn the whole board off because there is obviously something shonky about this set up. Still the lights stayed on! I am now thinking that the light is wired into the CU upstairs, but the tenant wasn't in. The scary thing is this has been two flats for years...

A.

 

[kingeri]

Had something similar last year, all the sockets for both flats and the communal area were on one poor customers CU. He was wondering why his electric bills were so high. I checked the whole installation, nothing particularly dangerous, good workmanship, just seems to have been a genuine oversight. I split the ring with minimal fuss.

 

[telectrix]

let us know the outcome when you find it.

 

[adiewadie247]

Will do.

 

[oldtimer]

I have had this with burglar alarms when for some unexplained reason the alarm technician wired the 1.5mm supply cable straight into the live side of the consumer unit so check this out as well. other than that get the tenant in the other flat to throw their isolator and if they get sniffy about then tell them it is to clear up if they are paying for downstairs leccy.

PS did you switch of the whole DB in the flat affected as I was asked by a mate to help him out as he had the same problem and he showed me each circuit being switched off and on and yes the light stayed on so the look on his face when I switched off the main isolator and the light went out hows that then ? well the 2 light circuits were interconnected so the light was getting a duel feed.

 

[adiewadie247]

Yes. I did end up switching off the whole board as none of the individual MCBs did the job. There are are no wires coming out of the wrong side of the MCBs unless they are very well hidden...

 

[Paul.M]

A very good point from Oldtimer regarding duel feed.

I would check that both flats are on the same phase, if not and later down the line extensions/mods are done their could get 400V on the lighting circuit. BANG.