Author Topic: Weird kitchen light wiring issue - any help/suggestions appreciated.  (Read 315 times)

caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
So we bought a new kitchen light for the ceiling as when cleaning the shade for the old one, my better half decided that reaffixing it correctly was not required resulting in it falling and smashing on the floor a couple of weeks back.  :facepalm:


Anyway, today I turned the mains fuse box off and wired in the new one.  Was a very strange wiring situation going on coming out of the ceiling....


Not one but THREE sets of mains wires.  So, I decided the best bet was just to wire all three live wires into the live wire chock-thingy bit - clearly labelled - then wire the neutral wires (all three) into the neutral bit and all three earth wires into the earth bit.


Jobs a goodun so far.  Assembled the light fully, switched fuse box back on and the light  came on.  :thumbsup:   And a thing of beauty it is :-)


But.... as soon as the wall switch was flicked - boom, it blew the trip switch in the fuse box in the garage. Hmmmm.  Did this repeatedly so we essentially couldn't turn it off without tripping out all the downstairs lights.


So after a breather (I'd blown my own fuse doing this several times  - a very irritating, ping-fukkety job it was) I removed the light again, got some insulation tape out and investigated whether wiring in just one set of live wires would be better.


So I separated all the wires into groups of three arising from the same main wire casing (if you see what I mean).


First two sets of wires simply didn't work at all.  Third set I got more success.  So the light now works without blowing the trip switches....


But now the wall switch - that used to operate the old light - just fine and dandy - now does nothing at all.  ??? ??? ???   So the only way we can turn the new light off is to go into the garage and flip the relevant trip-switch.


Since it's now too dark to do much more, this is our default at least until tomorrow.


I have checked the wall switch and well- it's a correctly wired switch that was perfectly functional until the new light got put into the ceiling...




Anyone have any suggestions possible solutions?  Right stumped I am - wiring in a light should be ummm - a piece of piss.  :-\


(I suspect this might require the services of an electrician to be honest -but any useful suggestions on what to do otherwise would be most cool)
It's a reverse Elvis thing.

Re: Weird kitchen light wiring issue - any help/suggestions appreciated.
« Reply #1 on: October 12, 2019, 04:52:54 pm »
probably the three wires are

1) part of the lighting circuit ring (earth, live and  neutral)
2) same as 1)
3) wire to switch. When the switch is closed the Brown  and Blue wires are connected to one another.


Thus if you 'star' all those wires together the light will always be on, but when you close the switch you can make a dead short in the lighting circuit.

You needed to copy the wiring that was there before, not make up your own.

With the power off everything disconnected again and something to test continuity you can identify which wires are a dead short between Brown and Blue when the switch is on. Using a voltmeter you can confirm that there are no volts in the switch when the wires are disconnected and the ppower is on (careful now).

cheers

Re: Weird kitchen light wiring issue - any help/suggestions appreciated.
« Reply #2 on: October 12, 2019, 04:54:57 pm »
What you have is standard lighting wiring, for the UK at least.

One cable comes from the fusebox. One cable continues on to the rest of the lights on that circuit. The last cable goes to the switch. Sometimes the cable to the switch has both wires the same colour, sometimes there is a bit of tape to show that the wire with the neutral colour isn't neutral.

(wire colours here are live - red if old, brown if new. Neutral - black if old, blue if new. I'll uses names in this post as I don't know which colours you have)

The earth wires, if present, are all connected together. The earth wires are uninsulated, and if really really old, that's all you have. If really old, you have a green sleeve around them. If old or new (following the timescales above) you will have a green / yellow sleeve around them.

The live wires of all three cables are connected together. The neutrals of the cable from the fusebox, the cable to the rest of the lights and the neutral of the lamp itself are connected together. The neutral of the wire to the switch (the one that may be coloured differently or may have a bit of tape) is connected to the live of the lamp.

For pictures, google "ceiling rose wiring".

I hope this helps. A bit of a cross post with Brucey.

Quote from: Kim
Paging Diver300.  Diver300 to the GSM Trimphone, please...

Re: Weird kitchen light wiring issue - any help/suggestions appreciated.
« Reply #3 on: October 12, 2019, 05:02:46 pm »
[edit to add: yeah, what everyone else said while I went looking for some links with pictures]

Sounds normal for standard loop in wiring (wiring connections all done at the light fitting, not a junction box elsewhere).

One twin and earth cable is the live/neutral feed from the main “fuse box” (permanent live)

The second is the loop down to the light switch (switched live)

The third is the feed to the next light fitting which is probably not working now (or it could be cable left behind from a fitting that was removed at some point, if everything else is working ok)

One of these links might help explain

https://www.diydoctor.org.uk/projects/ceilingrose.htm

https://www.practicaldiy.com/electrics/lighting-wiring/light-wiring-loop.php

Next time, take a picture before disconnecting stuff. DAHIKT.

caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
Re: Weird kitchen light wiring issue - any help/suggestions appreciated.
« Reply #4 on: October 12, 2019, 05:02:59 pm »
Wow that's actually really useful - thanks both.


Hmm, so I think I borked it up.  I was telling my wife.... one of the 'neutral' wires was masquerading as a neutral wire - I took the red sleeve it had on it and chucked it  :facepalm:   So that will have been that special one you were talking about.  :facepalm: :facepalm:


Ho hum - off to buy a multimeter it is then... or I might just take the hint that I'm clearly not-competent at this and get someone in  :facepalm:
It's a reverse Elvis thing.

caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
Re: Weird kitchen light wiring issue - any help/suggestions appreciated.
« Reply #5 on: October 12, 2019, 05:06:34 pm »
Also I fitted the light that was there before - replacing what was there when we bought the house in 2007 - so taking a picture of a cowboy-fitted light fitting my not be optimal ;)


Strangely, incidentally, the house was built in 2003 - so cannot really count as old - but the wire colours are yellow/green for earth and black and red for neutral-live.  Odd
It's a reverse Elvis thing.

tonycollinet

  • No Longer a western province of Númenor
Re: Weird kitchen light wiring issue - any help/suggestions appreciated.
« Reply #6 on: October 25, 2019, 06:57:55 am »
Black red were used up until 2006 when the regs changed.