Premier Elite 24 Night Set - Bells On at 3AM Trying to Understand Log

1 Jul 2007
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United Kingdom
Recently upgraded a Premier Elite 24 with a wired expander and SmartCom, last night it was on part set 1 (night set), bells fired at 03:05am, the log shows both a door vibration sensor and a D20 PIR both went to alarm state at the exact same time and restored at the exact same time, I find this hard to believe, they are different sides of the house on different cables, CCTV showed nothing. Copy of the log entries below, does this seem normal?


Also, should the Bell Active be in a Not Reported event group?
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Check connections on expander, aux power issue.
Check for induced A/C voltage on your system.
Checked expander, all connections seem good, just realised when you mentioned induced AC voltage I ran the cable to the office PIR in the same 25mm conduit as a mains lighting cable to an outdoor 9W LED PIR wall light, could that be an issue? The PIR didn't switch on at the time of the alarm though.
Not good practice to run low volts cables with mains cables. This could be a starting point.Do you have a multimeter?
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Yeah got all sorts of meters, what do you suggest I measure?

I should have known better with the cabling, I am actually an electronics engineer, do you think a spike upset the resistance readings?

The zones that triggered were 5 and 7 on the expander (last 2 with powered resistance devices), 6 is just a contact and 8 is unused, I am wondering if a spike on Z5 upset the Z5 and Z7 resistance readings?

To make it worse I just remembered I also ran a POE IP camera cable in the same conduit :oops:
Set volt meter on A|C range, place neg lead on earth and pos lead on + 12volts in main control panel.What is that reading ?. More than 1.5v ?.
Suggest you if a ACT 1313 filter.
Check aux voltage at both devices …and the power connections at the expander ,
Took some measurements, AC induced showing 3.0 volts, if I remove the 12V wires from the expander it drops to 1.1 volts so it seems the 12V wiring from the expander to the detectors is where most is getting induced. I suspect most of it is from the wire in the conduit with the mains cable, I'll disconnect that one wire and see what reading I get. Looks like I need to do some re-routing and probably add a filter :(
Took some more measurements, the 12V on the expander drops to 1V AC but the main panel 12V is still showing 3V AC, the original install by an alarm company has mains wires in same trunking and wires disappearing under the floors next to mains cables, is the solution just to filter it?

Do you fit 2 filters, one on the main PCB 12V and another on the expander 12V, its an 8XE internal expander?
Re-done all the measurements with 2 different meters, with all the Aux 12V red and black on the main panel and the expander all disconnected I still see 2.9V AC across the 12V terminals on panel and expander, the AC seems to already be on the power lines of the PCB.
No one filter will do …have you measured the dc voltage at the two devices that false alarmed ?
No one filter will do …have you measured the dc voltage at the two devices that false alarmed ?
Not yet but will report back later, adding a 2200uF capacitor between the 12V+ and mains earth removes all the AC down to 0.000V, I guess the filter is pretty basic, could be just a capacitor?
Voltage at the vibration sensor is 13.66 and at the PIR 13.68

With the capacitor in place between earth and +12V there is now zero AC measured on the 12V at the panel.

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