Home electrics - peculiar landing light behaviour.

[David Paste]

:D

Ah no, I have to say that the previous owner is the superstar who inflicted this, and many, MANY other eff-ups on the place. Gnashing of teeth is a frequent event.

[David Paste]

Cheers John.

It isn't my house, and one I only get to see every month or so. It is a family member who has recently moved in to it. The previous owner was a bit of a "let's have a go!" type. Some of his "improvements" are anything but.

It's a 1950s (or so) house, but none of us have any idea of the age of the wiring. The lighting circuit is using red & black wires though, from what I saw. There is also an electric car charging circuit.

The problem has been present since they moved in, so I suspect that it was never actually fixed from when the tic turd wired it in.

I just don't understand how the two circuits can be cross-contaminated if they are supposed to be separate.

Thanks for the links, I shall give them a thorough read.

[David Paste]

I'm OK investigating things, I know my limitations. Actually rectifying anything will be taken a lot more cautiously.

Ha! :)

[David Paste]

Doesn't come on at all.

[David Paste]

Yes, that's right.

Yes.

LED (from IKEA)

Thanks.

[Roger Hayter]

Then I agree with the person who suggested that the landing light has no neutral supply from its own circuit, but the neutral terminal of the actual lamp holder is connected only to the live of the upstair circuit. When the upstairs circuit is unpowered there is enough leakage from live to neutral upstairs (through lights that are on or perhaps a transformer or something else which is always on like a fan controller) to allow sufficient current from the downstairs live (when the proper switches for the landing light are in an on position) which is correctly connected through the landing light bulb and then via the upstairs live (which is disconnected at the CU as you say) to the upstairs neutral, which is still connected to the house neutral as the MCB for the upstairs circuit is single pole. It doesn't take much current to drive an LED.

Perhaps more complex miswiring could also account for the findings, but this seems the most simple explanation! It is quite conventional to use twin and earth cable to a switch so that both the red (in old wiring) conventionally live wire and the black (in old wiring) conventionally neutral wire are connected to live. In this case the black wire should have had red sleeving near the terminal. It is quite possible that in borrowing a neutral from the upstairs circuit (which is forbidden for many reasons) the person who wired the landing light in fact connected his borrowed 'neutral' to a live black wire in a handy nearby terminal. He may have missed the sleeving or may never have used it.

Roger Hayter

[John Rumm]

Its possible the lighting circuits are original... Once check would be to see if they have earthing. Pre 1966 there was no requirement for lighting circuits to be earthed.

ok that makes it a bit harder to identify likely places to look remotely!

One possibility is that the system uses a deprecated wiring configuration like this:

Where the live feed is taken from the switch downstairs, and then the neutral for the lamp is connected to that of the circuit upstairs.

However in this case an error has connected it to a live from upstairs. So it only works when power to the upstairs circuit is off, and it cans "see" an neutral though the loads (i.e. other lamps) upstairs.

It would help to know what types of lamps are in use as well.

[John Rumm]

One very common problem can occur when someone fiddles with a ceiling rose, and they get confused by the cable that connects to the switch, since it has one live and one neutral, but in fact both are live - one permanent and one switched.

[harry]

Probably a "borrowed neutral" ie a neutral that should be on the upstairs circuit is connected to the downstairs.

[ARW]

Until you swap a light fitting.....

[Brian Gaff (Sofa]

If its always done it sounds a bit like somebody has used a live from the do upstairs circuit somewhere, I'm surprised all sorts of other funnies do not occur as well, though but the two way switch might be to blame here. Brian

[Brian Gaff (Sofa]

Would not that result in a bit of a bang? I was pondering though if its not something similar. What about putting tungsten bulbs in, does that make any difference?I remember when our house was rewired, the electrician had one light you could not actually turn off, was just a crossed switch and live in the rose in the end he said. Brian

[Dave Liquorice]

neutral"

Sorry don't follow. I'm thinking of CU's with nothing but a main switch and single pole MCBs/Fuses. All the neutrals are joined together at the CU. Once you start separating the neutrals via RCD's, RCBO's or a split load CU then you have to be careful.

"Fitting" to me is the fancy bit with the light bulbs etc connected by just two wires, SW live and a neutral to the ceiling rose. (+ earth if the fitting is metallic).

[ARW]

Remove that pendant on the upstairs light with the upstairs MCB off and you could well soon be swearing when you find out the landing light is on the downstairs circuit MCB and has borrowed a neutral from the upstairs lighting circuit

[newshound]

Yes indeed. Many years ago I put in a "rise and fall" lamp for the dinner table and my friend and neighbour decided he had to have one too. A Cambridge trained medical doctor with research at Oxford, London, and somewhere Ivy League. He could have equally successfully pursued alternative careers as an opera singer or a professional golfer.

When he called me in, I found all the reds wired together, and all the blacks.

[Dave Plowman (News]

Not usual to find funnies with lights on two floors with two way switching. When there are separate circuits for the floors.

[PeterC]

When I was changing luminaires and going (almost) all LED I rewired the landing and hall so that they are both supplied entirely by the downstairs circuit. This circuit has about 60% of the lighting load on it but the total for the two MCBs, inc. the florries in the loft, is around 200W so the 6A MCBs aren't exactly overloaded.

[David Paste]

This is what bothers me. It is such a stupid mistake to make, especially if it was the bloke who lived there who did the wiring. Means he's just lived with the bullshit rather than fixing his own mistakes. What else is lurking?!

[David Paste]

Thanks John. I will do a better recording of the details next time I am there.

[Andy Burns]

Neighbour had builders in, they dropped the kitchen ceiling, connected all the loose wires exactly like that then left for the evening ...