2 way lighting with jumper

[steve447]

Downstairs lighting circuit trips as soon as connected to the mcb.
There is a two way switch next to a one way switch in a dual box, the one way is for a light in the hallway (on downstairs circuit), the 2 way for the landing light at top of the stairs (on the upstairs circuit). There is a jumper between the two switches.
I dont have the option of running a 3core and earth between the 2 switches due to a newly installed and decorated bathroom (tiled floors) smack bang above the switches in the hallway. So running a feed from the downstairs circuit to the landing light is pointless.
The only way i can think of getting around this is to put the 2 lighting circuits on to one Mcb?

I been staring at this too long now and im certain im missing something obvious, any thoughts?

Its a 17th edition board by the way so the intention was to have upstairs and downstairs split across the two sides.

Thanks in advance
Steve

 

[Octopus]

Sounds like you have a borrowed neutral

 

[Adam W]

Yeah, borrowed neutral.

 

[Electricalserv]

This is coming up more and more frequently on board changes..

 

[Octopus]

Sounds like you will have to put them on the same RCD, comment on EIC and recommend customer allows to to quote to seperate the 2 circuits properly and then put them on different RCD's

 

[Knobhead]

OK so what is the lad to do with it?
I’m sorry but pontificating about the cause doesn’t create a solution.

Added too late murdoch beat me

 

[steve447]

Thanks Murdoch

 

[Bradzz]

is it a new build. If im reading this right, so you have to seperate phase feeds to the consumer unit from the lights, what about nuetrals,
what happens to the upstairs lighting when the link is removed?
im wondering if the upstairs landing light is on with the down stairs lights and someone has also linked it in with the upsatiars lights?
have another look and come back to us

 

[steve447]

If i was to separate the two circuits, i would have no other option but to disturb the newly decorated (and by the looks of it expensive) bathroom by running the strappers between the two switches, or is there another option?

Is this a common thing, this shared neutal. I must admit i have not come across it before, but am not very experienced when it comes to domestics.

 

[Bradzz]

so if you knock the supply off to the down stairs lights the upsatairs lighting goes out as well in all rooms upstairs.

 

[steve447]

is it a new build. If im reading this right, so you have to seperate phase feeds to the consumer unit from the lights, what about nuetrals,
what happens to the upstairs lighting when the link is removed?
im wondering if the upstairs landing light is on with the down stairs lights and someone has also linked it in with the upsatiars lights?
have another look and come back to us

Cheers Bradzz .. It is not a new build, its a old house but wiring doesnt look to be as old as the house, although some of the switches were (and the sockets in the bedrooms spurred all off one of the sockets downstairs was dodgy, but thats another story) .
Yes there is two seperate feeds from the consumer unit, it was a old 4 way wylex with mcb carriers replacing the wired fuses. Ill have to check tomorrow what happens when the link is removed, i cant be certain at the minute as my head is scrambled.
The landing light is definitely on the downstairs circuit, but in the rose it comes from the upstairs bathroom and then goes off to the loft light, both of which stay ON when i turn off the mcb for the downstairs lighting and the landing light goes off.

Im sure its something simple but at the mo i cant see it.

 

[Bradzz]

until tomorrow

 

[nickblake]

OK let me thinks have you replaced the CDU if so and its to a new 17th edition board what you need to do is to test the neutrals and see if they are connected either via the lives or a link to neutral , what happens with a shared neutral is when the lighting circuits are installed they used to use double insulated singles linking the landing light to the ground floor lighting for the 2 way switching but then use a neutral for the first floor lighting hence when its mentioned a shared neutral very common during the late 60's early 70's , there are a few ways you can over come this problem one easy way is to install both lighting circuits on the same RCD side of the board or take a neutral from the ground floor lighting circuit to the landing light (im asuming its this thats causing the problem normally is ) so a bit of twin and earth just connect up the neutral to a groung floor lighting circuit and to the light in question IE the landing light ,if of course it is that one easy way to find out is to connect both lighting circuits to the same side of the RCD and try it , then disconnect the neutral and of the ground floor lights and see if the landing light still work , then switch off the first floor lights and see if the landing light still works if so then thats where your shared neutral is dont forget to put disconnected neutral into a terminal block while carrying out this test , if it is this light ,disconnect the neutral from this point and connect the neutral to it as stated before then lable the CDU with what you have done ,hope that helps

 

[BlueToBits]

Yep you have a borrowed neutral.

Option 1: The ideal way of dealing with this is to replace the 2 core strap wire with a 3 core but if you can't get at it, you have to be a bit creative...

Option 2: run a neutral and earth from from the downstairs lighting circuit to the landing light and remove anything else connected to the landing light maintaining continuity as needed. This may be easier if there is an unused core in the cable between the landing switch and the landing light. If so, you may be able to get a cable up the tube (?) from the floor below to the switch.

Option 3: (fairly cheap) Fit a pulse operated latching relay in an adaptable box in the loft and change the hall and landing light switches to a push on / push off type. For example:
http://www.hevacomphelp.com/elec/1pdf/HAG/0033.PDF

Option 4: (less cheap) use proprietary wireless control switches to replace the 2 switches such as "Wise Controls"

 

[Hawk81]

The way I would do it would be to remove the neutral to the landing light from the upstairs circuit and take a neutral from the downstairs circuit

 

[Bradzz]

see if you can up load a couple of photo's.

 

[steve447]

was unable to get to the ceiling rose or the loft today as there is some plastering going on in one of the rooms and they have moved all the furniture into the landing.
I checked what happened with the link removed as Bradzz asked and all the lighting worked except for the landing light.
I will try both nickblakes and blue to bits advice as soon as i can.
Thanks to all who have made suggestions.

As bluetobits post about the unused core in the cable, it used to be there but someone has snipped it off. Also getting anything else down the tube is going to be a mare, not much room there at all. Also it appears that everything from the original wylex board is chased into the wall up the staircase and fed up to the loft and then dropped down from there including the downstairs ring. It was a crazy system. The downstairs ring dropped from the loft into the kitchen and then run round the whole of the downstairs, then in the dining room there was a 2.5mm run back upstairs into a J/B which then split 3 ways to feed 1 single socket in each room.

Steve

 

[BlueToBits]

was unable to get to the ceiling rose or the loft today as there is some plastering going on in one of the rooms and they have moved all the furniture into the landing.
I checked what happened with the link removed as Bradzz asked and all the lighting worked except for the landing light.
I will try both nickblakes and blue to bits advice as soon as i can.
Thanks to all who have made suggestions.

As bluetobits post about the unused core in the cable, it used to be there but someone has snipped it off. Also getting anything else down the tube is going to be a mare, not much room there at all. Also it appears that everything from the original wylex board is chased into the wall up the staircase and fed up to the loft and then dropped down from there including the downstairs ring. It was a crazy system. The downstairs ring dropped from the loft into the kitchen and then run round the whole of the downstairs, then in the dining room there was a 2.5mm run back upstairs into a J/B which then split 3 ways to feed 1 single socket in each room.

Steve

Have a look at this
W I S E C O N T R O L S
and check out the recievers too.