Two way dimmers single switch

[Nijinski001]

Tihis sounds like a really stupid question but I can't get my head around it today.

What is the best way to wire the following?

Downstairs cellar kitchen - two banks of recessed spots on a double dimmer.
Upstairs - 3 gang switch with one gang not currently used.
I want to connect the 3rd gang to be a two way switch controlling both banks of spots downstairs.

The issue is both 3 core/earth wires will need to be connected to the same switch gang. I also know that if one bank of spots is on and the other is off then switching upstairs will reverse this so to be effective both banks of spots have to be either on or off.

Is there a possibility of a short or conflict?

Is there a better way of doing it other than swapping the 3 gang switch for a four gang switch?

 

[Steve]

Is there a better way of doing it other than swapping the 3 gang switch for a four gang switch?

not as far as i know. Though one way to do it would be to make the upstairs switch a master switch, and have it in parallel with the 2 downstairs switches, but this is not 2 way switching.

What is the purpose of this upstairs switch - why do you envisage needing it?

 

[Nijinski001]

Typical 2 way switching scenario really.
Get to the top if the stairs and realise that you a
have left the downstairs lights on or switch from the top on the way down to save searching for a light switch in the dark.

 

[Steve]

so you can actually see the downstairs lit area from upstairs? If not, i would advise you to label this upstairs switch if you do use it. My mum and dad have lived in this house for 19 years, and they still dont know which switch does what at the bottom of the stairs, and theres only 2 switches!

 

[ban-all-sheds]

Replace it with a 2-gang architrave switch - I'm sure even they would be able to grasp the concept that the top switch was for upstairs and the bottom one for downstairs....