Opening front door is triggering my house alarm

[Zack660]

Definitely only 2 wires into the door contact Motman. I am going to try your idea first as I do think it might be a cable or contact problem due to the intermittent nature of the issue.
Will let you know how i get on.

 

[Mottie]

If that makes no difference, try a test length of wire from the control panel entry/exit circuit (you probably won't be able to set the alarm with the c/p cover off unless you hold down the panel tamper switch). If that cures it, it's the wire. If it doesn't, it's the panel.

 

[Zack660]

Thanks Motman, the hard part is working out which are the 2 wires in the control panel that have come from the door contact.
I wonder if they don't go straight back to the panel, and instead go via the pir sensor in the hallway? Is it possible they are in series?

 

[Mottie]

Normally they are seperate and it should be marked entry/exit in the panel. You normally find that the hall pir is disabled when the entry/exit is triggered to allow persons coming via the correct entry route to get to the keypad without triggering an alarm.

 

[Zack660]

Ok folks! Think we have got somewhere. Tried Motmans suggestion and alarm worked fine with correct entry /exit procedure. So tried it again with pir unmasked, and again worked fine.
This made me think the issue is the door contact itself. So put old contact back on, but left the new magnet side on. Lo and behold it seems to be working again.
Obviously was originally an intermittent fault so will need to check over next few days, but fingers crossed!!!!!!!
Couldn't have worked this out without your knowledge and logic guys. Really appreciate your help.
Thanks Zack.

 

[Mottie]

May have been a weak magnet. Check the air gap between the two units.

 

[Zack660]

Is about 12mm. Would have thought this was okay??

 

[Doggit]

Nope, too far, the magnet might be weakening. Reduce it to about 5mm, and that should make it more consitant, and hopefully, cure the problem.