Lighting Junction Conundrum

Frenche · Jan 20, 2013

Hi, this is my first post. I've wired up a few lights in the house previously but stumped on this one. No electrical testing equipment, but quite competent DIY-er so any advice appreciated.

We took a ceiling rose down and marked all cables, but tape slipped off. The are 4 cables with 3 wires in each, two of the cables are the old colours (earth plus blue and brown), the other two are newer (earth, red and black). The ceiling rose shares the same on/off switch as another landing light, and both are operated by 2 wall switches (one downstairs, one up).

We've attached all the earths together, all lives together and all neutrals together. We've identified what we believe to be the live switch (using forums etc), and attach the new light live to that. The new light neutral goes with the other neutrals.

When The live switch identified is isolated, all other upstairs lights work (except the two landing lights which are the problem).

When attaching the new light, it won't turn on, and it's twin light (on the same light switch) won't turn off! It is only a dim light though.

Not sure what we are doing wrong. Any help greatly appreciated! Thanks

Sidewinder · Jan 20, 2013

OK,

First mistake, brown & blue are NEW colours, black & red are OLD colours.

You have two way switching on the lights.

Next, you need to identify which cables go where and do what.

There is no god given standard for wiring 2 way lighting which says which cable/core does what, it is up to the spark who installed it unfortunately.

ProDave · Jan 20, 2013

How many CABLES do you have (not how many cores)

You talk about 4 cables, then go on to describe just two.

Barx · Jan 20, 2013

Agree with above really. An educated guess would say the 4 cables are as follows

2 will be the 'Loops' - perment line and neutral into the fitting and out to the next fitting (and obviously earth)

1 will be the 'switch wire' - takes perment line to the switch and brings back the switched line when the switch is operated.

1 will be the 'link wire' - link the 'other' fitting to this one, so connects to neutral, earth and switched line.

Now, which is which is impossible to tell with out sort of testing.

betty swollocks · Jan 20, 2013

Ok from what you have said and the way you have explained it I believe what you have done is connected the permanent live and neutral to the separate landing light thus making it stay on, the reason your new landing light won't work (and be carefully here) could be because you actually have connected the switch live believing it to be a neutral and a permanent live - so the light is not working because you have two lives at the light connections.

You need to go back to basics.

To re-identify the cables you have. Four cables two red/black two brown/blue. Two of these cables will be mains supply into the ceiling rose and out of the ceiling rose. One cable will go to the switch. One cable will go to the other landing light. You could remove he switch cover to see what colour wires are there and do the same at the other landing light and let us know the findings.

ProDave · Jan 20, 2013

In all honesty, if you don't have ANY test equipment (not even a multi meter) there's not a lot you can do Even an electrician would have to make some measurements to determine for sure which wire does what..

Call in a local electrician, it won't take him long and if he's a decent bloke it should not cost you much.

If you had a meter, and knew how to use it we could suggest some tests to determine which wire is which.