We recently moved into a new apartment in Berlin. We are the first occupants and thus there are no existing lighting fixtures. In the living room there are 4 light switches (1 & 2 on the left of the room, 3 & 4 on the right) and 5 cables dangling from the ceiling:
- Green/Yellow: Earth
- Blue: Neutral
- Brown: Live when switches 1 or 3 are on
- Black: Live when switches 2 or 4 are on
- Grey: Gets a "small" current when switches 2/4 are on.
By small current I mean - the only tool I have is a simple test light. When the Brown/Black wires are active the test light glows very brightly, but when the Grey wire is active the test light is very dim.
I get that there are two sets of three way switches here, but what is the Grey wire for then?
According to https://en.wikipedia.org/wiki/Electrical_wiring#Colour_code Black, Grey, Brown are colour codes for 3 phase, but I don't know what that means as far as installing a ceiling light goes here.
Any help much appreciated!