House wiring - check me on this please

[pgkevet]

I;ve just been redecorating sitting room..swapped out the wall lights and go a new ceiling light to go up.
The ceiling plate up there has a 3 section connector block with 3 parts to each section and a seperate earth block.
There is only one switch that works this light (that i can find - this is an old house)
All switches and sockets are new types and the main board in all modern trip types.

On this ceiling section i have 3 black wires into one negative block and one blue into another section there. the negative of the light I removed was into the third compartment.
The middle section has 2 reds into oen block and another red into another block. The third section which had the light fitting positive has one yellow wire.
the 3 or 4 earths (it's a bit tangled) all go into their own block and had a stub from there earthing the fitting.

My non-contact power detector lights up on the reds and the yellow whichever way the wall switch is.

I assume therefore that the reds are looping on as power from other lights elsewhere in the circuit and the wall switch is switching on the negative? Even that doesn't make obvious sense since the negatives all should be joined....

The room above has a laminated floor so taking a look at the wire directions under floorbords isn't possible.

Annoyingly there isn't enough room under the new fitting to hide this ceiling plate or hide multiple extra connector blocks and the wires are too short to be able to tuck 4 into the new fitting's block. I see my only practicable solution to make a 3/4 in thick wooden disc with a central hole to fit over the current ceiling plate and then mount the new fitting on that with three short sections of connecting flex...

[BASS 666]

all your lights should be switched live..

[pgkevet]

[QUOTE=BASS 666;1071588]all your lights should be switched live..[/QUOTE]

I'm aware of that.

I'm still trying to understand this. It actually doesn't make sense to be switched on the negative either since there's 4 negs together..either that switch would be controlling all 4 negs which would be daft since that would be controlling a whole bunch of lights and it isn't and I don't see how it was being controlled by the switch - which it was - when the positive shows power when the switch if off...

I've just cut a disc to fit over the ceiling plate (since the new fitting base isn't deep enough) out of MDF and I'll mount it over that plate and mount the new lights onto my disc and pull my spurs as they were before. If it works - and it should - then it'll have to do.

If nothing else its the first practical thing I've made on my cheapo spindle turning lathe since I've owned it

[milly0812]

You have what's called a three plate ceiling rose. You have lives,neutrals and switch line. It's basically a junction box to take the feeds and neutrals to the different rooms on that circuit. I'm not up to date with the regs on how to join cables now but in your situation they used to join them in connector blocks and push them up into the ceiling and extend the switch line and neutral to fit to the new light in place of the existing ceiling rose.

[pgkevet]

[QUOTE=milly0812;1071618]You have what's called a three plate ceiling rose. You have lives,neutrals and switch line. It's basically a junction box to take the feeds and neutrals to the different rooms on that circuit. I'm not up to date with the regs on how to join cables now but in your situation they used to join them in connector blocks and push them up into the ceiling and extend the switch line and neutral to fit to the new light in place of the existing ceiling rose.[/QUOTE]

I figured it had to be something like that.. just very confused that my non-contact detector shows power on the yellow (live to lights) even when the switch is off. Actually the only answer i can come up with is that the bloody detector is over sensitive and somehow picking up when it shouldn't...

..still my mdf disc should solve my issue.. thnaks

[pgkevet]

This is starting to make some unfortunate sense :-(

I wired up the new lamp to the same points the previous was wired to: the yellow, the neutral block and the earth block. Popped in a new led bulb which switches on with the wall switch fine BUT still glows faintly when the wall switch is off. The previosu fitting used low energy flourescent bulbs and I;m guessing that low current leakage didn;t show up on them.

It explains why the yellow was triggering my non-contact detector even when the wall switch was off yesterday.

The wall switch wiring makes no sense to me. It's a double switch running the wall lights too.. which work normally. BUT there's two reds, one yellow one black and one blue. The black and blue are connected together and not to the switch anywhere. I can;t read the switch terminals (unless I unwire it fully) but I have the yellow top of the one switch, a red bottom of that switch but feeding a loop to the top of the other switch part and another red at the bottom of the second switch.

Maybe just a leaky switch but looks new enough.

I've put a call into local sparks..but around here getting anyone to actually do something...like even turn up..... well holding your breath and you'll choke..

I also tried disconnecting my live feed to the new lamps just in case there was some power somehow via neutral to earth.. but no glow like that: definately some power leakage in the yellow wire even when the wall switch is off and not tripping fuses.

[pgkevet]

If I worry at a problem long enough I hope to figure most things out.

Next step has to be a new wall switch ...for the sake of £2.. but I'll open it up again and run my non-contact tester over the wires. I figure that the original sparks must have run a 3-core with a yellow in it so he knew which was the feed to the ceiling and run a 2 core from the wall lights. If so the two neutrals do nothing so he terminated them in a connector block. The yellow is the out feed from the wall switch to the ceiling and there's a red as the live feed in for both ceiling and wall with the other red as the feed out to the wall lights.. the spur red loops power to the wall lights part of the switch.

Assuming that's so then logic says there's a fault in the switch and it doesn't quite cut all power..high resistance but enough leaks through to glow the led bulb. If that's so then I ought to be able to prove at least that there's no short in the yellow by swapping it into the out feed for the wall lights....

[pgkevet]

At least I admit I'm slow working it out..

Disconnected yellow wire in the switch and still picking up voltage on it.. disconnected it at the ceiling end too..and still voltage. To me that mplies that someone probably stick anail thrugh the cable..somewhere up in the ceiling..or rather under the bedroom above floorboards. the ony rpoblem is that I had continuous laminated flooring run through the whole upstairs..sigh..

[milly0812]

I would have thought that any short caused by a nail would trip the breaker ?. Do you have 2 way switching on that light ? Ie 2 switches controlling the same light like the top and bottom of stairs.

[pgkevet]

[QUOTE=milly0812;1072164]I would have thought that any short caused by a nail would trip the breaker ?. Do you have 2 way switching on that light ? Ie 2 switches controlling the same light like the top and bottom of stairs.[/QUOTE]

Not if the 'short' is live to live. can't see any evidence of two-way switching. The switch isn't wired for that and no other visible switch involved (although you never know what's buried inside walls from previous owners). This house has been chopped about in it's past. the only resolution i see is the painful one of lifting laminated flooring, underlay, floorboards and looking <deep sigh>. Well unless one was going to leave a potentially live wire about and put up with a pull-switch on the ceiling or a load of trunking or a series of ceiling holes and wall channeling to repair after running a new line. Whatever i do the other half will moan about mess and disruption.

Some days ya thinks the easy way is just cap off the ceiling fitting, stick a smoke detector on it to make it look pretty and just live with the wall lights...

[Grant85]

Did you ever manage to get this problem sorted mate?
Cheers,
Grant.


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[pgkevet]

It's a job still pending - wife refused to let me rip up the bedroom floor before christmas plus I found a local chap to help me with outside work and had a knackering 4 weeks clearing middle field woodland fence line and logging up felled trees. Now it's too soggy for field work I need to start clearing the room and getting on with it. It doesn't help that I'm not keen on doing it.. my back usually goes into spasm quickly when crawling around doing that sorta stuff so it's a cycle of chewing pain relief and stretching out between bits of work...
..getting older isn't fun..

[Grant85]

Wouldn't it not be easier to take a picture of the ceiling rose and the back of the light switch so we can get a better understanding of what all the cables may be doing. Sounds like some cables havn't been sleeved up properly and may well have been connected into wrong points. For example, just because it's a blue or black cable doesn't necessarily mean that it's a neutral.


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[pgkevet]

I'm pretty confident that the problem is the yellow wire to the wall switch partially getting a live source into it somewhere on it's route - even disconnected at both ceiling plate and wall switch my detector picks up power each end. Its not just a case of a short bit of sleeving at each end - it's yellow as far as one can see so probbaly it's whole length. I'm guessing someone whacked a nail thrugh a floor board or a close nail chafed a bit over time. It's gonna need visual inspection of it and any parallel wires and eal with the dodgy section or replace full length.
It just took me onger than it should to figure it out.

What I really need is a couple of enthusiastic pilots without back problems that want a weekends flying and fixing and send the wife away for a few days..... I just can't guarantee the weather this time of year...Actually i can - It's Wales so it's either rain or snow <g>

[Grant85]

That yellow cable will run with a blue and a red then as a 3 core inside grey PVC. An insulation test between all three cores needs to be carried out then if you may think a nail could've gone through it. If so then I am quite surprised that it hasn't shorted out with the yellow being right at the side of the blue (neutral) or as you say it may have just gone inbetween the yellow and red. Assuming the red is the permanet live (which usually is) and the yellow being the switch live. And has led to leakage across the two.
If you have a multimeter you could always try a continuity test between the end of the red and yellow? And if you do well have continuity then this is the case. Try that?


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