light fitting in bathroom

[keenbutconfused]

Hello. Have been looking on the internet for a while now and although haven't managed to find an answer to my question do feel an enormous sense of relief in finding a group of people who between them seem to have an enormous body of knowledge and the willingness to help people like me (electricity newcomer) out. I hope you can help
Have taken down existing light fitting in bathroom and have found 2 cables that seem confusing.

Electrics in bathroom are as follows. One pull switch which turns the one light fitting on and off. When I turn on the light the fan also comes on. There is an isolator switch whcih can be used to turn off the fan whilst the light is still on. When the light is turned off the fan stays on and then turns itself off after about 5 minutes. There is also a shaver socket.

There are two cables coming into the light fitting. One has a red cable. a black cable and a thicker cables with a black casing which I am asusming is a wrongly cased earth. The second cable is 'three-core and earth'.

Firstly, does anybody know why the 'three-core-and earth' cable be used to go direct to the light fitting?

Secondly, the earth cable from the cable with red, black and "black" is connected to the blue neutral wires in the light fitting and the blue cable from the 'three-core-and-earth' is connected to the same point. Can anybody think of any reason why this might be? Is it dangerous?

Any help would really be appreciated.

 

[andy]

Hello. Have been looking on the internet for a while now and although haven't managed to find an answer to my question do feel an enormous sense of relief in finding a group of people who between them seem to have an enormous body of knowledge and the willingness to help people like me (electricity newcomer) out. I hope you can help
Have taken down existing light fitting in bathroom and have found 2 cables that seem confusing.

Electrics in bathroom are as follows. One pull switch which turns the one light fitting on and off. When I turn on the light the fan also comes on. There is an isolator switch whcih can be used to turn off the fan whilst the light is still on. When the light is turned off the fan stays on and then turns itself off after about 5 minutes. There is also a shaver socket.

There are two cables coming into the light fitting. One has a red cable. a black cable and a thicker cables with a black casing which I am asusming is a wrongly cased earth. The second cable is 'three-core and earth'.

Firstly, does anybody know why the 'three-core-and earth' cable be used to go direct to the light fitting?

Secondly, the earth cable from the cable with red, black and "black" is connected to the blue neutral wires in the light fitting and the blue cable from the 'three-core-and-earth' is connected to the same point. Can anybody think of any reason why this might be? Is it dangerous?

Any help would really be appreciated.

1:the 3 core goes to the fan. live, sw. live and neutral.


2: could be for the shaver socket. any chance of a diagram? would make it easier to understand the wiring you have

 

[securespark]

That sounds dodgy. Any situation where you find an earth conductor sleeved otherwise and connected to anything other tha an earth terminal is plain wrong, and it must be investigated and rectified.

But we need pictures ideally.

If you have a multimeter, you can check which of these is live when the light is on, and therefore which one is the feed in to the fitting. The trouble is, there may be any number of joints, so it is not possible to say whether the other cable is for the fan, shaver socket or otherwise.

Logically speaking, a 3 core and cpc would be used for the fan, but if we apply logic, there wouldn't be an earth used for a neutral.....

Post some pics, and do a bit of testing with a MM and get back.

 

[keenbutconfused]

I have drawn a diagram that shows the light fitting. I also had a look at the inside the pull cord and have drawn a diagram there too. As you can see again whoever did this sleeved what is normally the earth cable black and connected it up to the neutral.





Inside the shaver socker all the earth cables are connected up together and then to the metal case inside the shaver socket. So that all looks good.

My confusion is that currently it all works, my problem is that I am not sure if I were to connect the new light fitting and use the available earth cable in the light fitting if it would actually be earthed.

Any ideas? Thanks for you time and help by the way.

 

[andy]

it looks as tho the cable to the far right (T+E) is the main feed to the system. from there the red is used as a perm live and goes to the light fitting. this is then connected as the perm. live to the fan. and black of the T+E from the switch to light is used as the neutral for the light and the fan. the earth in the T+E has been used as the neutral from the switch to light and then to fan. basically he's used the earth as a switched live instead of using 3C+E form switch to light. this should be resolved ASAP. also, since there is no earth at the light you cannot use a metal fitting. and metal fittings shouldnt be used n a bathroom anyway

to sort this mess out: put 3C+E from switch to light. connnect red to incoming red. connect blue to incoming black, and sleeve the blue as black. connect yelloe (sleeved red) to the swtch in place of black.

at light: connect red to fan red. connect blue (sleeved black) to neutral to fan, which is yellow (sleeve black). connect yellow (sleeved red) to blue (sleeved red)


last thing: whats probably happened is it was orignally wired w/o the fan, and earth used as an earth. then someone has added a fan. instead of taking the 3C+E to switch to get its feed, they have taken it to the light, only to find there is no perm live, so they have used the earth as a neutral

 

[pdcelec]

very eloquently described

 

[andy]

very eloquently described

at first i thought the 3C+E was the feed for some reason, and the actual feed was the supply to the shaver.

 

[ban-all-sheds]

I wonder what else the numbnut who did that has done?

 

[andy]

I wonder what else the numbnut who did that has done?

i dare not think

 

[keenbutconfused]

Andrew2022

Thanks so much for your help. Sounds spot on given the history of the house. Room was a bedroom originally. Fortunately the fan wiring was done in last few years after rest of wiring was done so this cowboy hasn't been let loose on any other parts of my house thank god.

Re: your instructions. Everything you said makes sense at the pull cord switch. However, I am confused about what happens at the light.

You said the yellow that I should connect to where the black currently is on the switch, should be connected to the neutral or blue at the light. However, currently the wire that is connected between the switch and the light is connected to the brown or live. You have suggested a similar thing with the blue wire (ie swopping the way it is currently connected) that will replace the currently sleeved earth wire. Can you confirm that this is correct?

Secondly, can you clarify just how dangerous this is and in what way. I am on a tight budget but at the same time will not stint on necessities.

Is there any way that it can be fixed without putting in 3C&E? Sounds unlikely!

Aside from the lack of earth is there something about the earth wire that makes it unsuitable to be used in this way, ie is it made of a different material. Is there a fire hazard?

Secondly, if I used a plastic light fitting that didn't require earthing would there be a problem.


Lastly, there is an earth cable that is spare in the pull cord switch, presumably this is still an effective earth for the switch, however it doesn't carry the earth to the light fitting.

However, having looke at the shaver socket that is connected to the isolator all the earth cables are attached together and are attached to the metal casing behind the shaver socket, a single green and yellwo wire then goes from there and leads downwards towards the sinks water pipes. If this is an effective earth via supplementary bonding (??? not sure if this is right terminology) then would the spare green and yellow earth in the light fitting be an effective earth and could therefore be used.

Is there a way of testing earthing?

Again thanks for your help.

 

[mapj1]

The only problems with using the bare core as a current carrying conductor is that it is reduced diameter copper and only single insulated (i.e you are relying on the outer sheath.)
Neither of these conditions is immediately dangerous, except in fully loaded circuits when the earth core may overheat, but it is certainly not something that should be left uncorrected in the longer term.
It is sometimes found when 1 way switching has been made 2 way also.

If you have a meter with an ohms range, then (with the power off, given what you have described) then using a long wander lead, or any reasonable copper wire clamped back to the main earth terminal, usually by the meter or fuse board You can confirm for a low resistance continuity to anything you think ought to be earthed.

The proper solution will involve a length of 3+E - is the ceiling void accessible?
Oh and wait for B-A-S to tell you it is part P notifiable, as it will not be a like-for-like substitution. You may decide not to worry about that.

 

[ban-all-sheds]

It is part P notifiable, (like-for-like is irrelevant, though). You may decide not to worry about that.

 

[andy]

ignore my rpevious description on how to wire

use this



NOTE: EARTHS HAVE BEEN OMMNITED FOR CLARITY. ALL EARTHS SHOULD BE CONNECTED TOGETHER. also, cores to be coloured with red/black sleeving, red if live, black if neutral
you must either change the cable from light to switch or youll loose the timer function on the fan

 

[keenbutconfused]

Changing the cable from the light to the pull cord is going to be close to impossible.

you must either change the cable from light to switch or youll loose the timer function on the fan

Would actually be preferable to lose the timer function on the fan instead of changing the cable. Is that possible and if so, how would I have to wire it? Would it then be considered a safe installation?

 

[andy]

Changing the cable from the light to the pull cord is going to be close to impossible.

you must either change the cable from light to switch or youll loose the timer function on the fan

Would actually be preferable to lose the timer function on the fan instead of changing the cable. Is that possible and if so, how would I have to wire it? Would it then be considered a safe installation?

in switch connect black to black, earth to earth and connect reds thru switch, one on each side.

at light, connect red from T+E to live on bulb. also connect red and yellow from 3C+E. connect black from T+E to neutral on light and connect blue from 3C+E to neutral. all earths should be connected to something. if no earth is needed, use choc block. sleeve 3C+E as appropriate