Fitting a ceiling light.

[Flynnwood]

It was a "borrowed neutral"? Edit to add; Or a broken neutral that your body earthed ?

That's only part of the answer Don't forget, I had the fuse in my pocket

The Neutral was adjoined with other flat(s) then ?

 

[SamG340]

@Lorenzl Yes - a neutral can be a problem if it belongs to "borrowed neutrals". That took me a while to understand.

@Paul555 Are you sure there is not a secondary consumer unit fitted somewhere?
Have a look at John Ward on proving electrical dead:

He's got to be THE most boring man I've ever seen. Good videos learnt a lot from him but WOW is he dull

 

[SamG340]

I might also be wrong with this but I think changing or replacing existing fittings is fine for DIY?

Yea for now !

 

[woodieallen]

Nope. Good try tho'

 

[woodieallen]

The Neutral was adjoined with other flat(s) then ?

Got it. The original sparks had mixed up a couple of neutral wires between the flat I was working on and another. So someone in the other fat might have been wondering why his ring main suddenly stopped working .....LOL

 

[jcassidy]

I was replacing an upstairs light fitting, had the lights circuit off at the consumer box, tested for live, dead as a dodo, happy days, off comes the old fitting, wires not sleeved so where are those sleeves? Oops, I left them in the shed, popped out to get them, literally 2 minutes, back up on the chair with the exposed wires inches from my face, test for live out of pure habit and BZZZZZZ! Nearly fell of the chair. WTF?

Turns out SWMBO was collecting the laundry, popped the breaker back with a broom handle so she could see what she was doing and then couldnt reach to turn it off again, and then forgot all about it.

 

[Ozi]

Yea for now !

Except in wetted areas kitchen and bathroom I believe but there will be an electrician here who knows for sure

 

[SamG340]

Except in wetted areas kitchen and bathroom I believe but there will be an electrician here who knows for sure

That's what I read anyway , think you can do it yourself but you have to pay a 3 figure fee to the council + have it inspected by a qualified spark

 

[SamG340]

I was replacing an upstairs light fitting, had the lights circuit off at the consumer box, tested for live, dead as a dodo, happy days, off comes the old fitting, wires not sleeved so where are those sleeves? Oops, I left them in the shed, popped out to get them, literally 2 minutes, back up on the chair with the exposed wires inches from my face, test for live out of pure habit and BZZZZZZ! Nearly fell of the chair. WTF?

Turns out SWMBO was collecting the laundry, popped the breaker back with a broom handle so she could see what she was doing and then couldnt reach to turn it off again, and then forgot all about it.

Women

 

[Pedronicus]

Was the fuse in the neutral line?

 

[Scruples]

I'm a qualified electrician (retired) and even us pro's can get caught out. Replacing a consumer unit in a flat in a block that was wired with old style metal conduits and single core red and black wires. Turned off the old consumer unit. Went into the landing utility cupboard and removed the fuse feeding the flat. Tested the incomer - with two different testers. Dead as a Dodo. Proceeded to undo all the wires (after labelling them up). Fixed the new consumer unit to the wall and proceeded to reconnect the cables. My knuckle brushed against a neutral and to my surprise got a belt. Tested the neutral - it was live.

Your starter for ten. How could that happen ?

Neutral inversion? It can happen when the earth has failed somewhere in the supply line.

 

[GuitardoctorW7]

Maybe emergency lighting battery backup feeding back via the neutral in box? Seems odd when the main breaker was off. Get a cheap meter or probe. I normally just trip the circuit I am working on but always check after its off. I also put a piece of insulating tape over the MCB so no-one can turn it back on when I am working on it and a sign on the box

Sounds like it was a split board. The lighting circuit is independent so that if there's a fault in the main rings/radials the lights stay on so that you're not plunged into darkness. The lights will have their own separate breaker

 

[Phil Pascoe]

Got it. The original sparks had mixed up a couple of neutral wires between the flat I was working on and another. So someone in the other flat might have been wondering why his ring main suddenly stopped working .....LOL

This one has cropped up here somewhere before. Might have been Roger S.