how to replace door contacts?

thanks mattlait,the problem is that the old contact was buried into the wall when a new door was fitted,and i cannot get to it.
is there a way still round this to find the correct coloured wires,can i just keep trying coloured wires until i get a match??

geo
May 2009

just look at the wires that come off the old contact. you might have 2 pairs(1 alarm pair and 1 tamper pair)or sometimes just 1 alarm pair. if you take apart the contact you should be able to see which terminals the reed switch in the contact is connected to, these 2 wires will be your alarm pair and if you do have another pair then that will be your tamper pair

mattlait
May 2009