Add a third switch to existing 2 way light fitting

[dannit]

Hi,

I need to add a third switch to an existing arrangement. Here's how it operates just now...

Downstairs switch (three switches).
One operates the Outside Porch
One operates the Downstairs light
One operates the Upstairs light - 2 way system

Upstairs switch (one switch).
This operates the Upstairs light only - 2 way system

NEW switch in Upstairs hallway.
I need to run a cable from the new switch to the existing switch to operate a 3 way system to work the upstairs light but how should I cable it ie. which cables to which terminals? I've been looking at the WIKI area of this site which shows a diagram of a 3 way system with intermediate. But does it mean I have to change the Upstairs switch to become the Intermediate switch and then the NEW Upstairs Hallway switch becomes the 2 Way switch? Please help.

I attach photographs to show you what I'm trying to explain.

Hope someone can help me out there.

Thank you, Danni

 

[chris765]

You need to run an intermediate switch.

It will be easier to help if when you take some pictures of the wiring behind the switches?

If your 2 way is wired in the 'conversion method' which I guess it might be and the upstairs is the second switch, then its a matter of replacing the upstairs switch with an intermediate switch, run 3core+earth to the new switch and use the old upstairs switch here.

But pics will determine this

 

[holmslaw]

..

 

[dannit]

Hi ChrisLee765,

I'm not too good at using this site yet. I thought I added pictures showing cables behind the switches - can't you view them?

Danni

 

[dannit]

Thank you Holmslaw. That makes complete sense to me. Much appreciated.

Danni

 

[chris765]

No I couldn't see them

I'm pleased you understood holmslaw's description, happy wiring

 

[dannit]

Oops. I'll have another try at downloading pics next time (cos I'm sure there will be a next time!) Thanks for your help too ChrisLee765.