Replacing a piece of cable in the ceiling

[notsurewhattoputhere]

Hi,

The plug socket Fused spur unit for my cooker hood stopped working and after doing troubleshooting I've discovered that there's no continuity between the positive wire at the socket and a light fixing where it is connected to a junction box Luster Terminal. (I know its the right wire as there's continuity between the negative and earth here.)

What's the best way to replace this piece of wire, its about 1m long and I don't really fancy cutting a hole in the ceiling, or emptying the upstairs room so I can lift the floor boards up ?

Thanks

(Edited to fix the name of some items)

 

[riveralt]

What's the best way to replace this piece of wire, its about 1m long and I don't really fancy cutting a (A) hole in the ceiling, or (B) emptying the upstairs room so I can lift the floor boards up ?

Thanks

A or B or dc

 

[17thman]

do you mean there is continuity between both ends of NEUTRAL and both ends of earth and no continuity between both ends of LINE(live)?

 

[notsurewhattoputhere]

do you mean there is continuity between both ends of NEUTRAL and both ends of earth and no continuity between both ends of LINE(live)?

Yes

 

[EFLImpudence]

Have you disconnected the Neutral and Earth wires from the light fitting?

You shouldn't have a socket (assuming you mean a normal 13A socket) on the lighting circuit.

Are you certain you have the correct cable?

 

[riveralt]

Have you tried plugging your cooker hood into a socket that you know does work?

 

[17thman]

if your results are correct, you may have a hidden screwed connection as a continuous conductor is unlikely to fail. lift the boards for peace of mind, or you may get lucky attaching a new length of cable to the old and pulling it through.

 

[sparkwright]

If there is a break in the LIVE (not positive) remember a fuse could have blown, or a single pole switch could have been turned off.

 

[notsurewhattoputhere]

Have you disconnected the Neutral and Earth wires from the light fitting?

You shouldn't have a socket (assuming you mean a normal 13A socket) on the lighting circuit.

Are you certain you have the correct cable?

Hi,

I removed the entire light fitting so I just had the wires, then tested each one for continuity with the wires at the socket.

A Neutral and Earth wire had continuity but the Live did not.

So I'm as certain as I can be that this is the correct cable without physically being able to look at it.


I need to apologise for causing some confusion as I'm sure you guessed by me calling the wires by the wrong name, my knowledge of the proper names for things isn't too great.

By "Plug Socket" I meant "fused spur unit" and also it isn't a junction box the wire is connected to at the light fitting but a "Luster Terminal"

 

[notsurewhattoputhere]

Have you tried plugging your cooker hood into a socket that you know does work?

Hi,

Yes I attached a plug to the wire and plugged it into a known good socket and the cooker hood works fine

 

[notsurewhattoputhere]

If there is a break in the LIVE (not positive) remember a fuse could have blown, or a single pole switch could have been turned off.

Hi,

I checked the fuse in the fused spur unit and it was fine. I can't find a switch for this socket, and it was working fine until one day it just stopped without anyone doing anything.

 

[riveralt]

Have you tried plugging your cooker hood into a socket that you know does work?

Hi,
Yes I attached a plug to the wire and plugged it into a known good socket and the cooker hood works fine

Okay the cooker hood is not the problem.
What I cannot understand and perhaps you could explain is how the kitchen light and the cooker hood worked together.
Did you switch the light on at the wall plate switch and the fan came on together?
Did you switch the light on the wall plate switch and then a switch on the cooker hood to make both work together.
Also how did you test continuity between live and ??? Did you physically remove the conductors from the Fused Connection Unit - in which case which one the supply or the load?
At one end you should have connected say the live and earth together in a terminal block and then tested between live and earth at the light switch.

 

[notsurewhattoputhere]

Have you tried plugging your cooker hood into a socket that you know does work?

Hi,
Yes I attached a plug to the wire and plugged it into a known good socket and the cooker hood works fine

Okay the cooker hood is not the problem.
What I cannot understand and perhaps you could explain is how the kitchen light and the cooker hood worked together.
Did you switch the light on at the wall plate switch and the fan came on together?
Did you switch the light on the wall plate switch and then a switch on the cooker hood to make both work together.
Also how did you test continuity between live and ??? Did you physically remove the conductors from the Fused Connection Unit - in which case which one the supply or the load?
At one end you should have connected say the live and earth together in a terminal block and then tested between live and earth at the light switch.

Hi,

The 2nd one.

There is a light switch on the wall which makes the light come on, and a separate switch on the cooker hood to make it come on.


To check continuity I removed the wires from the FCU on the wall so I had, Live, Neutral and Earth just poking out from the wall.

Then I had my multimeter set to continuity mode and placed one probe on say the neutral wire at the wall and then touched each wire at the light fixing (the light fixing was removed and the wires were removed from the luster terminal so there were just a bunch of wires hanging out the ceiling. with the other probe until it beeped.

It beeped for the neutral and earth wire but no matter which wire I touched at the light fixing the Live wire wouldn't beep.

 

[riveralt]

Hi,
The 2nd one.
There is a light switch on the wall which makes the light come on, and a separate switch on the cooker hood to make it come on.
To check continuity I removed the wires from the FCU on the wall so I had, Live, Neutral and Earth just poking out from the wall.

Then I had my multimeter set to continuity mode and placed one probe on say the neutral wire at the wall and then touched each wire at the light fixing (the light fixing was removed and the wires were removed from the luster terminal so there were just a bunch of wires hanging out the ceiling. with the other probe until it beeped.

It beeped for the neutral and earth wire but no matter which wire I touched at the light fixing the Live wire wouldn't beep.

So I will assume that the light switch has nothing to do with the cooker. And if I understand you right the power to the cooker hood is derived from the junction box that feeds the kitchen light.

So assuming these cables are T&E have you able to identify and separate out which T&E has continuity on the neutral and earth but not on the live?
Just for completeness connect the live and earth together in a terminal block at the FCU and then test between live and earth at the other end of the T&E cable back at the ceiling light.

If you have identified this single T&E with its effectively broken live conductor (which is unusual) then you are back to the two options you/I highlighted at the beginning. As someone else said you might be lucky enough to be able to use the old cable to pull through a new one but otherwise its going to have to be a channel in the wall and possibly the ceiling - .

 

[radweld]

A Neutral and Earth wire had continuity but the Live did not.

So I'm as certain as I can be that this is the correct cable without physically being able to look at it.

From that, I think it's likely it's not the same cable. Before hacking the ceiling, I would repeat this measurement, then see if there is continuity between the 'disconnected' earth wire in the cable and a known good earth. I suspect there will be.