Lighting circuit - wired something the wrong way.

aliasojo

The whole bathroom got stripped today, not one shred of plasterboard is left. When I took the ceiling down, I noticed the joist that the light fitting was screwed to, was blackened and the cables going into the light fitting were brittle and black.

Got a hold of the electrician on the phone (he's been out here regularly ) who reckoned the light fitting, which was poor quality and not suitable for a bathroom, had literally burned them and all that was needed (apart from a new light fitting) was new cable.

So, there were 3 cables coming from the centre bathroom light fitting....one going to the wall switch, one going to the bedroom light and one going to the shaver socket. I ran new cables and redid the connections to the bedroom light and the bathroom lightswitch. The shaver connection was left off because of the refit.

The cables which would go to the new light fitting, I put in connector blocks as a temporary measure as the ceiling will be getting plasterboarded tomorrow. I just put all 3 reds together, all 3 blacks together and all 3 neutrals together.

I've obviously done something wrong as the rcd safety device in the main consumer unit has tripped and we have no lights up stairs.

Can't get hold of electrician at the moment but I'm sure this is something simple, likely conected to the 3 cables I've put in the connector boxes.

Anyone help?

Ephemera

Leave your lights off and wait for the sparky to turn up!!!!!

Something is very wrong there if your consumer unit keeps tripping out. It may be there is a short somewhere else in your wiring, or the original wiring is wrong in some way.

Find some other way of lighting your upstairs for one night....

Good luck!

aliasojo

Thanks.

Anyone else give me pointers please?

espresso

By connecting all of the blacks together, you are shorting out the switched supply (black) from the switch.

If the following means nothing to you, get help from from someone who understands basic electrics.

aamuk

By going on what you have said, the problem is probably going to be the wires coming from the switch. All the reds together are fine, but the black from the light switch is actually the switched live - so should not be connected to the other blacks. It is the live that returns from the switch to the light fitting.

Also, I'm guessing that you mean all the earths (bare copper with green/yellow sleeves) are together when you say neutrals.

aliasojo

Thanks very much, I knew it was the way I'd put them together in the blocks! I thought it was the live but didn't want to faff about any more until I'd checked.

I'll go change it.

Electrician will be coming out at some point shortly to do other stuff so I'll get him to check what I've done.

Yes, neutrals = earths. I'm old, lol.

ormus

on lighting circuits, some neutral blacks can actually become live reds!

amarg

It's not difficult to understand if you are shown correctly. An electrician will do this with his eyes closed because he does it every day, but a DIYer might only do it a few times in a lifetime.

This should help explain-

light wiring

light fitting

ceiling rose wiring

Psychobabble

aliasojo wrote: »

So, there were 3 cables coming from the centre bathroom light fitting....one going to the wall switch, one going to the bedroom light and one going to the shaver socket. I ran new cables and redid the connections to the bedroom light and the bathroom lightswitch. The shaver connection was left off because of the refit.

The cables which would go to the new light fitting, I put in connector blocks as a temporary measure as the ceiling will be getting plasterboarded tomorrow. I just put all 3 reds together, all 3 blacks together and all 3 neutrals together.

The cable from the bedroom is the Live wire(red), Neutral wire (black) and Earth wire(will be bare copper but should have Green/Yellow sleeving put on it) feed to the light.

The one to the shaver socket is the feed to it from the main light, again Live(Red), Neutral(Black) and Earth(Green/Yellow).

the cable to the Switch is the
Live(red),
Switched live, (Black, but should be marked with red tape or sleeving to indicate its the switch wire)
and Earth(G/Y)

you will need 4 connector blocks not 3

Block 1, connect the 3 Live(red) wires together

Block 2, connect the 2 Neutral(black) wires from the bedroom and the shaver together.

Block 3, connect the 3 Earth (Green/yellow) cables together.

Block 4, connect the Switched live (Black, but should be marked with red tape or sleeving to indicate its the switch wire), this should be by itself.