Bwthyn

Hello all, I fitted an alarm system a few years ago and put contact breakers on my windows. To save on wiring I "shared" the different wires within the 6 core cable I used between 2 zones, with a common tamper circuit, on the rear of my property. I have now had sliding sash windows fitted which have made the contacts unsuitable. I was thinking of replacing them with vibration detectors but noticed that some have LED's. I assume this means that they need a power source to operate - the same as the wiring for a PIR detector. Are non-powered vibration detectors available or will I have to rewire with 8 core in order to maintain my zone separation? Thanks for any help you can give me. Paul