DIY disaster: bathroom light fitting

scorza

scorza

scorza

Caporegime
Joined
22 Jun 2004
Posts
26,684
Location
Deep England
Right, have a new light I need to fit to my old bathroom (it's IP44 certified so it's suitable), so first job was to remove the old light. Once that's done I accidentally drop it on the floor and break it - oh well, no going back now. Here comes the problem though, the old light fitting seems to have no less than four mains cables coming down from the ceiling. Three of them contain the standard neutral-live-earth (black, red, green) configuration, one of them has light blue, yellow, red wires coming out of it.

Thing is, my new light fitting only requires one mains cable, so I guess my question is are they all mains cables, if so what do I do with the other three cables? If not, how do I tell which one is?

Now I also have an extractor fan in the bathroom that's supposed to come on when you switch the lights on, could it be that the wiring for that is routed through the light fitting?
 
The yellow, blue, red cable is a three core and earth cable, it's for the fan.

Three core
------------
Red= permnanent live, for the over-run timer.
Yellow = switchwire.
Blue = neutral.

Twin core
------------
just red and blacks.

===============

The whole system is using loop in by the sounds of it.

All the reds get lumped together.
2 blacks go together.
1 black as your switchwire.

How the whole thing works is the reds take power and loop to next light, the neutrals are similar but a single red and black is going to the switch, the red takes the power down, and when the switch is thrown the black (switchwire) brings the power back to the light.

To fix it, leave out the fan cable for now.
- Lump your reds together with connector block (minus the red from the fan).
- Put the two blacks together that seem to belong together (same kink in the cable, same markings to the copper where they were connected before), those are the neutrals. Put them in one connection in the fitting.
Put the single black in the other connection of the fitting.

If that works okay, power off and then add the fan blue to the neutrals. the red to the other (lumped together) reds. The yellow to the single black.

If you ain't sure at all, tape up all cable ends and call in a spark.
 
Cheers helmet, think you've just confirmed what I suspected already. I've been over ambitious and will need to call in an electrician :( I thought the ceiling rose was part of the old light fitting so unscrewed it all ffs. Thing is my new light is supposed to fit flush to the ceiling, so I can't use it with a ceiling rose anyway.

Edit: Will undoing the ceiling rose explain why all my upstairs lights aren't working now?
 
It sounds more tricky than it is.
If you have circuit breakers in your house you can "try" to fix it.

Just be sure that the power is off for all lighting circuits, all the 6amp breakers.

join all reds except the fan cable together with connector block.
Then join two blacks together and try the breaker. If it will not reset that is a dead short so you are wrapping two blacks that don't belong together.
Rinse, repeat until your upstairs lights work.

If you have a set of test lamps (instruments) this would be much easier, post back if you do.

connector block up all ends after each try, the fan cable can be left bare it will not have any juice flowing from/to it.

And to answer your other post, yeah it can go flush, connector block up the cables and push them back up into the gap where the cables come in :).
 
Last edited:
good luck mate I spent ages explaining this to my dad years ago then to my wife but they just didn't "get it" lol.

For me it just seems totally logical. hehe
 
Don't try and identify which blacks go together by trial and error and trying to close the MCB onto a fault :eek:

And don't engergise the circuit with unterminated conductors hanging out ceiling :eek:

Identify the switch cable using a continuity tester
 
It's classed as like for like so don't actually need a minor works cert.

Tbh mate you seem a little out of your depth. Call an electrician in. Should take him 5 mins to sort out (It's simple for us lot lol) So I can't see it being too much really.

I Think we are going to end up having to have a ban to electrical help threads like medical threads before someone gets told to do something horribly wrong and burns their house down. :/
 
Rich1988 said:
I thought legally you had to be a certified electrician even to work on your own electrics now?
Click to expand...

Even if true, who cares :confused: ?

Always do things yourself imo to save money...


Shame you messed up this time, you'll know how to do it for next time tho...
 
Last edited:
I do a fair bit of electrical stuff at home. Best thing that I do now is if changing a socket, light fitting etc etc, and if there are loads of cables running to/from it, I take a picture, and then terminal block each lump of cables together as I take them out.

Today I've replaced our kitchen light, as well as installing strip lights to the underside and topside of the cabinets, and changed all the plastic sockets for nice metal decorative ones.

Have also run some new sockets (yes, in a proper ring), and two new fused spurs for different things. Have also run cabling and installed the electrics for our underfloor heating, and oven. New garden lights also.

I generally think the new rules regarding doing your own electrics are a bit over the top, H&S taken far too far! As long as you know what you are doing and do it properly, I can't see a problem.
 
Over Clocker said:
I do a fair bit of electrical stuff at home. Best thing that I do now is if changing a socket, light fitting etc etc, and if there are loads of cables running to/from it, I take a picture, and then terminal block each lump of cables together as I take them out.

Today I've replaced our kitchen light, as well as installing strip lights to the underside and topside of the cabinets, and changed all the plastic sockets for nice metal decorative ones.

Have also run some new sockets (yes, in a proper ring), and two new fused spurs for different things. Have also run cabling and installed the electrics for our underfloor heating, and oven. New garden lights also.

I generally think the new rules regarding doing your own electrics are a bit over the top, H&S taken far too far! As long as you know what you are doing and do it properly, I can't see a problem.
Click to expand...

Did you test these circuits? I'm not talking turning them on and they are working. I'm talking continuity tests for your rings. IR tests, R1+R2, ZS tests, ZE at the CU? PFC? RCD test?
 
You must log in or register to reply here.
Back
Top Bottom