I have a wired home security system that's been installed and working fine for over ten years. I would like to add a second magnetic contact to an existing window (that already has a contact). I've been reading about this and it seems the easiest way would be to wire the second contact in series. My question is how do I wire it? I have 2 wires (black and yellow) connected on the first contact on the window. Also does this setup require adding a resistor?
Thanks for the help
Thanks for the help