Wiring for three way switch

Apreciar

Have rcently had workmen in fitting kitchens etc. Since they left a three way switch to the garage which is operated from the utility room blows the mcb or rcd. They have been back once and thought it was the new switch which was fitted, however, I have tried the old switch which was removed and this still causes the same problem.

Question, how do you know which way the two non common wires connect or is this not important. I have checked on ultimate hanyman on the three way wiring and understand what it says but how do I know which of the two non common wires are which.

ormus

(old colors).

yellow should be the common.
red should be L1 and blue L2.
yellow and blue wires should have red tape on, to show they are switched live at some point.

Apreciar

ormus wrote: »

(old colors).

yellow should be the common.
red should be L1 and blue L2.
yellow and blue wires should have red tape on, to show they are switched live at some point.

The problem is that the original switch using the old colours is now behind a unit with the live and switched live going to the light fitment, from here he has run a cable - new clors - to the new switch. So the cable has black grey and brown. I know the brown is the common but what about the other two.
Of course this will assume he has wired the d*mn thing properly.

Apreciar

Earlier I said that " I know the brown is the common", it would appear that this is not correct but this is how the fitters left it. If I rewire the switch with brown to L1 Black to L2 and grey to common should this sort the problem out.

ormus

new colors.

grey is the common.
brown is L1 and black is L2.

grey and black wires should have brown tape on to show they are a switched live.