SAT IN DARKNESS - CHANGED LIGHT FITTING AND THREE ROOMS WENT

[lushy78]

Here's hoping someone can help! We have just moved into a dated property and my husband changed the lights downstairs with no problem. However last night he took the old spotlight down from our spare room and said the wires were different to the others he had done. There were three sets of wires all red and black coming through the ceiling.

He had no idea how to wire it given that the others only had two and as such shocked himself! Initially all the lights in the house went out so I located the fuse box - turns out to be one of those black old fashioned things with no trips switches. So I replaced the fuse wire and hey presto the lights came on, except in three of the upstairs rooms.

We now have no idea what to do given that the extent of our electrical training is rewiring a plug in science class all of twenty years ago. Does anyone have any idea what weve or should I say he, has done and how we go about rectifying this.

Many thanks indeed

 

[Spark123]

//www.diynot.com/wiki/electrics:lighting:problems:blackswlive

 

[Taylortwocities]

Hve a look here //www.diynot.com/forums/viewtopic.php?p=35550#35550 at the very first item.

The junction will have feed in, feed out and a switch wire. if you connect all the reds and blacks together then the fuse will blow when you turn on the switch. Just because the wire is black does not make it a neutral.

If he does electrical work with the power on then he will either end up in hospital or in a box in the ground.

 

[bongos]

It sounds like you have 'loop in' wiring at the ceiling rose. One red/balck pair will be the feed from the previous room, another will be the feed to the next room (this is why you have lost lights after this room).

The third red/black pair will be the live/switched live for the switch. The black for this one should have red sleeving on the black core.

All reds (live) go together in the live loop. Two blacks go together in the neutral. The remaining black with red sleeving is the switched live and will nedd to be connected to the fitting.

See here for more info.

 

[lushy78]

Thank you for all your replies, hopefully you will have enabled my husband to come out from the dog house! I've read all the info and yes as you have guessed he did just bunch them all together without realising the significance of the red on the black. Will wait till morning to have a go at sorting it out and will let you know if we are successful. thanks again to all of you.

 

[Chri5]

He has made the very common error of thinking all the wires of the same colour should be joined together.

Not so on lighting circuits with 3 x cable to a fitting.

Without access to simple electrical test equipment it may be better to call in a sparks who will resolve the problem in 10 minutes flat.

Basically the 3 cables are (1)live from further downstream of the circuit (2) live upstream and (3) switched live for the lamp fitting.

So all the red (live) cables get joined together, the 2 black cables (neutrals) get joined togther and the 3rd black cable is the switched live (this should have had a bit of red tape on it).

The light fitting brown cable should terminate on the 3rd black cable and the light fitting blue cable should terminate on the 2 neutrals.

Ignore the switching beyond the 1st switch and look at the junction set up on this diagram, that explains it as clearly as can be.

 

[ColJack]

what the hell are you doing changing the lights with the power ON???!!!!!!!

would you change a flat tyre whilst doing 70 down the motorway???

 

[flameport]

He had no idea how to wire it given that the others only had two and as such shocked himself!

... so I located the fuse box ...

We now have no idea what to do given that the extent of our electrical training is rewiring a plug in science class all of twenty years ago.

This is not meant to be insulting, but you should STOP what you are doing and call an electrician.

The first step should have been to locate the fuse box and turn off the power.

Working on live circuits, clearly having no understanding of how circuits work and not even knowing where the fuse box is located is incredibly dangerous. You were fortunate that your husband was only shocked and not killed.