Converting single switch to 2-way

[sossage]

I have a single hall light above my stairs controlled by a switch at the top.

I would like to change this to 2-way and install a switch at the bottom of the stairs too, for obvious reasons.

Question is: -

1) How do i wire this ?
2) What's the recommended way of running cable from top to bottom as obviously cable runs should be horizontal or vertical and not at the angle of the stairs ?

Thanks in advance,
Soss.

 

[spark]

Assuming you've got normal 3-plate domestic lighting, just run a 1/1.5mm 3-core+earth (6243Y), between your existing switch at the top of the stairs and your new switch at the bottom of the stairs. Get 2no 1-gang 2-way switches and connect as follows: top switch stick the red of the existing cable in with the yellow in L1, the black of the existing cable in with the blue in L2 and the red of the new cable in the COM (common) terminal. bottom of the stairs stick yellow in L1, blue in L2 and red in COM. Don't forget to sleeve and terminate your earths effectively and fit red over-sleeve on the yellow, blue and black cores at both switch positions to indicate that they are potentially live conductors. As for running the cable it's hard to say without seeing, but generally you'll run down the wall following a line directly below the switch, under the floor boards to above the new switch position and run down the wall directly above the new swtich position. Job done.

 

[sossage]

Great - thanks for this - i'll start taking up some flooring !!