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.