Light fitting wiring problem

[ajcflex]

Hi All,

does anyone know why I have found 3 sets of wiring arriving at one light fitting?

I have taken down a single bulb light fitting to put up a nicer one and have found 3 cables arriving at the light. At 1st I just followed the instructions and put the 3 earths in a choc bloc / the 3 lives in another choc bloc and the three nuetrals the same - then connected to the new fitting in the correct way.

The problem is that something is wrong as I cant get the fuse switch to turn back on.

Could there be a loop circuit ? How do I test to see whach ones I need to connect and which ones not to ??

Please help !!

 

[Roo]

By connecting all what you think are neutrals when infact 1 is probably a feed from the light switch you've created a dead short.


I'm not an electrician and will probably be told I'm wrong in a minute, but don't try and turn the MCB (fuse switch as you've called it) back on.

Phone an electrician

 

[Spark123]

Sounds like you have mistaken a switched live for a neutral:
//www.diynot.com/wiki/electrics:blackswlive

 

[ColJack]

this is commonly known as 3 plate wiring..

when you took the ceiling rose down, it had...

3 lives into a terminal marked "LOOP"

2 neutrals into a terminal marked "N"

1 switch wire into a terminal marked either "L" or "SW"


you should have marked the black / blue wire that went to the "L" or "SW" terminal....

you need to get yourself a continuity checker or multi-meter..

1. turn off every light in the house...

2. turn the power OFF

3. turn the ON light switch to the light you need to find ( NOTE: LIGHT SWITCH, NOT BREAKER!!! )

4. take the wires out of the terminals you have put them in and check between pairs or red and black cables until you find a pair that has continuity ( the meter will read zero and / or beep to indicate continuity.. )

5. this is your switch wire.. mark the black / blue with brown tape... DO IT NOW!!!!...

6. take the remaining blacks / blues and connect them to the neutral of the light fitting..

7. take the black / blue with brown tape and connect it to the live of the light fitting..

8. connect the earths ( sleeved with green yellow sleeving ) to the earth of the light fitting

9. take the 3 red / browns and connect them into a terminal block on their own.. no connection to the light....

10. fit the light to the roof and turn the power back on..


sorry if this seems a bit demeaning but i thought that writing it "idiots guide" style might be helpful..

 

[kevnurse]

Hi All,

does anyone know why I have found 3 sets of wiring arriving at one light fitting?

Yes. 1 cable is the live, neutral and earth supply from the previous light in the circuit. Another cable is the live, neutral and earth supply to the next light in the circuit (although one light, furthest from the fusebox, doesn't have this cable, because it is the last one on the circuit). Another cable carries the live, switched live (in a neutral coloured cable) and earth to the wall switch.

The switched live might have a sleeve or tag of the live colour.