wiring new kitchen light

[richie28]

Hi,

I had one of those fluorescent tube lights fitted in the kitchen when I moved in but last night took it down to reveal=

4 live wires
4 neutral wires
4 earth wires

I was expecting one of each, but maybe thats my lack of experience of electrics. I only wired two other lights and both had just the three wires.

anyway the light I purchased, had 4 bulb sockets. having again 4 live, 4 neutral but 1 earth wire.

connected the live wires together, neutral together and the single earth wire to the 4 earth wires. and presto light works however the problem is the light switch will not turn the light off!!!

-light switch before was working fine.
-its a double switch and still operates the other light (light outside above backdoor) so switch must be working.

any help please????? I took the light back down as I didnt want to risk anything.

 

[Adam_151]

Does it go bang when you try and switch it off? (normal switch or dimmer btw?)

 

[richie28]

Normal switch but doesnt make any noise at all, no bang.

 

[pcboffinuk]

Hi Richie,

4 is not that unusual a number of cables to find at a light.

Firstly, I hope you made a note of any connections between the cables before you took the light down? Otherwise you are going to have to get a multimeter out....


What I imagine you have is as follows:

1 cable in from the main power feed (Live/Neutral/Earth)
1 cable carrying on to the next light in the chain (Live/Neutral/Earth)
1 cable spurring off to feed another light (Live/Neutral/Earth)

1 cable looping through the switch to provide a switch live....


In this case, one of those 'Neutrals' is live, hence Adams question about going bang!

If installed correctly, one of the 'Neutral' (Black I presume unless done recently) should have red sleeving on it to denote that it is being used as a live return conductor from the switch.

Assuming that is what you have (a photo might help - or some more details about how it was wired before the light was taken off) then you will need to do the following:

All the true Neutrals together in junction box, terminal blocks or similar, together with the Neutral from the light.

The permanent Lives connected together, but NOT to the light.

The red on the 'switch' cable connected to the permanent Live

The black (switched live) on the switch cable, connected to the light Live terminal.

If you aren't sure which cable is which, then a multimeter may be the only way, but you really shouldn't do it since it requires the power being on to test which is the switched live.

There are other possibilities, so a few more details would help, and don't take any risks until you are sure what you have!

Hope that Helps


Gavin

 

[richie28]

thanks for the reply, some of that made sense to me but really I need to be talked to in complete layman terms. I got lost halfway through it....

is there a process of elimation I can do without causing a bang???

 

[SgtTrojan]

I get this quite a lot, and as i teach school leavers i will try to help you mate

FIRSTLY, ISOLATE THE CIRCUIT!! If you know the individual device, remove it or switch it off. If you don't know which it is, turn the whole board off.

1. Remove your switch and you should have a red and a black. The red should be connected in the terminal marked C. The black should be in one of the other terminals with red tape on it.

If this not the case, don't worry for now. We can come back to switching later. Four ease I am going to refer to the conductors by their colour and not by what they do.

2. At the ceiling position you have:

Four reds.
These are all permanent live (meaning they are not switched by anything other than the protection in the fuse/ breaker board). Get yourself a piece of connector block (15 amp- medium sized) big enough to fit all four conductors in and connect them all together.

Four blacks.
Three of these will be neutral.
One of them will be a switch wire and is the black which is connected to the switch.

Now.. does one of these blacks have red tape on at the light?
Do you know which one connected to the terminals supplied in the old light? If not, you are going to have to get your multimeter out. Without a meter or remembering which black was used as live you are up sheet creek.
There is a way of determining which condutor is switched live but you stated you are not fully competent so I cannot put you in any danger.

Once you have a meter follow this procedure. If the leads are long enough put one lead on the black at the switch and with the other lead touch each black at the light and only one of them will buzz or give you a reading. If the leads are too short you can always temporarily extend one of you leads with a piece of wire by twisting it around the end of the probe. Once you have found it this is the switched live so put some red tape on it.

If your leads are too short and you dont have any wire to extend the lead then let me know as this post is getting too long as it is

Three of those blacks will connect together into your new lights neutral (blue) terminal.
The other black should be identified as live with red tape and be connected into your new lights live (brown) terminal.

In all cases all the earths connect together in the lights earth terminal. They should all fit but iff not put them together in a piece of connector block and connect a short piece of earth wire to your new lights earth terminal.

Hope this helps.