Optima G3 false alarms

[Stevelmcd]

I have an intruder alarm system with an 8EP 396 Optima G3 compact panel which has been working perfectly for years. Recently I have been getting occasional false alarms, always on zone 2. It appears that these false alarms are triggered by someone switching a light on/off or by the central heating system switching on/off.
I have replaced the battery but no change.
If I link out zone 2, there is no problem.
Walk testing the system shows every sensor working OK but when activating a sensor on zone 2, instead of getting 2 bleeps continuously, every so often one or two pairs of bleeps are missing (e.g. bleep bleep, bleep bleep, bleep bleep, - -, bleep bleep etc), whereas the bleeps on zones 1, 3 & 4 don't miss.
Zone 2 has 5 magnetic door sensors (normally closed) and one pressure pad (normally open, connected across to the 0v terminal).
What do the missing bleeps indicate and how can the system be affected by switching external units on or off? What do you think is causing the false alarms?
Your comments and suggestions would be most welcome.

 

[denso13]

Maybe better in the Alarm section of the forum?

 

[Stevelmcd]

Thanks, but only a moderator can change this I think??

 

[oasistechnical]

do a resistance check on all devices connected to zone 2.

also check all connections are true and tight on all devices 5 door contacts is a bit high, but then you can fit as many as you want , as its your system!!!

we prefer to fit one device to one zone, its easier to fault find!!!

but try the above and let us know what happens and what readings you get

Oasis

 

[Stevelmcd]

Many thanks, oasistechnical for your prompt reply.

I take your point about easy fault diagnosis by having one sensor per zone but I have a total of 11 sensors, so I have main entry/exits on zone 1, downstairs on zone 2, upstairs on zone 3 and garage on zone 4, which makes life easy at night by just omitting zone 3.
Following your advice, I started checking resistances...

Whole of zone 2 + cabling when closed is 3.5 ohms
Pressure pad + its long cable when closed is 10 ohms
Each of 5 door sensors and the pad when tested separately (without cabling) are zero ohms when closed.
3 of the door sensors + their cabling are zero ohms when closed and the other two + their cabling are 3.5 ohms (long cables).

However, as a direct result of testing each sensor, I found by accident that if I physically disconnected 2 of the door sensors (not the long cable ones) from the zone and just had 3 doors plus the pad in circuit, the walk through test no longer missed any pairs of bleeps. So my conclusion is that these 2 sensors are faulty and I intend to replace these when I can get to the shops.

My only concern is that this doesn't explain why switching an external light switches or the heating programmer should trigger the alarm. Maybe this is just something weird which will be corrected when I replace the sensors. What do you think?

Anyway, many thanks, I will let you know the result when the work is done.

Steve

 

[Alarm]

Mains spikes would explain the above.
You cable could be running near mains.
You could have the panel on the same ring as the items causing the issue.

You could buy a spike mains filter.
http://www.actmeters.com/2323-Mainspike-Suppressor.php

 

[Stevelmcd]

Thanks Alarm for you interest and suggestions.

I agree that mains spikes could be a cause and will look into obtaining a filter as you suggest.
I can say that the control panel is connected on its own circuit from the fusebox but because this mains supply cable and the zone cables all pass through the wall together, they are in close proximity to each other. However, the cables have been like this for about 20 years, it just seems strange that this situation should suddenly evolve (assuming replacement of the two sensors doesn't solve it as I am hoping).

Steve

 

[Alarm]

Wear and tear on the switches, maybe arcing more when switching. Elements drawing more initial power? A few reasons why after 20 yrs things change.

 

[Stevelmcd]

Thanks very much, I take your point.
We'll see what the situation is when I have replaced the sensors.

 

[joe-90]

Try switching your alarm wires over with the tamper wires and see if the fault follows. (ie shows as a tamper fault).

 

[Stevelmcd]

Thanks Joe, a very logical test. Unfortunately this has no effect, i.e. the fault remains with the alarm circuit.

 

[Alarm]

Err joe, two circuits running one N/O one N/C (contact and pressure mat).
On same zone.

 

[Stevelmcd]

Just to clarify, the 5 normally closed sensors are connected directly to zone 2 terminals. The normally open pressure mat has one wire connected to zone 2 and the other wire connected to the 0v terminal and works fine.

 

[Europlex]

Just to clarify, the 5 normally closed sensors are connected directly to zone 2 terminals. The normally open pressure mat has one wire connected to zone 2 and the other wire connected to the 0v terminal and works fine.

Not really the correct way to do it I know, but what the h***, it works.

Poor Joe90 is only a wooden puppet, does not really understand how alarms used to work, back in the 'good old days' while he was only a sapling.

 

[Stevelmcd]

Sorry about the delay but I still haven't got my replacement sensors yet. Having ordered 4 (2 replacements and 2 spares) from Maplin last Monday, who appear to be the only source of the type of sensor I require, one was sent to my local store, so they re-ordered another 3, then the order was cancelled for some reason, and they didn't let me know! This was the story they gave me when I was forced to call in today as they haven't answered the phone since Thursday despite hanging on for several minutes at each attempt.
They have now had to re-order again.
However, I can say with some certainty that the 2 new sensors will solve the problem as I have been using the alarm without the 2 sensors in circuit since last Monday without any false alarms and walk through tests are faultless.
Many thanks to all of you for your interest and suggestions.