Security & Fire Protection Systems/False Alarms


QUESTION: I have a DSC Power 832 Main Control Panel with 1 zone expander Panel(Model PC 5010). I have 2 LCD5501Z digital keypads. The system has a total of 16 hard wired zones, 2 motion sensors, a fire/smoke detector and a siren. I've tested the system several times and it always checks out fine. I've had problems with false alarms in the past but usually during peak summer heat. We've been experiencing a colder than usual period where the house temp has been getting down to the low 60's and the false alarms have begun daily in the early mornings when the coldest house temps are reached. Just like the summer, none of the false alarms give a zone code on the keypads. I'm now pretty convinced that some part of the system is reacting to temperature extremes but it's not anything that points to any zone. Could it be the siren? Any help will be greatly appreciated!

ANSWER: Hi Juan:  Two things spring to mind.  

1.  Is your system hooked up to a telephone line?  An alarm without any zone identifier is indicative of a telephone line fault.  When the system's armed the siren will sound if your phone line is cut or interfered with.  I would suggest disabling the telephone line monitor.  To do so, you must have access to installer level programming.  If your system's monitored have the company dial in to your system and disable the phone line monitor.

2.  Check the connections between the keypads, zone expander and common control.  A loose connection here with the system armed will sound the siren as well (with no specific zone indication).  If it's a loose connection, you won't wind up with the tamper when you disarm because it resets automatically.

Hope this helps.

---------- FOLLOW-UP ----------

QUESTION: First of all...Thanks very much!

I do have access to installer level programming.

Relative to #1, I am not being monitored so I have already disabled the "Telephone Line Monitor" and the "Communicator - Dialing".

Relative to #2, I will check the connections (again) but I'm not sure what you mean by "common control".

I didn't arm the system last night but I did get a trouble beep this morning at about the same time. Temperature sure does seem to be a factor.

The common control is the the DSC main board (inside the metal cabinet).  Please ensure you power down the system completely before you start messing around with the wires.  I'm pretty sure you'll find the culprit causing the problem in the wiring to the keybus.  This will have red, black, green and yellow wires connected all in the same area (more to the left centre of the bottom side of the board).  If all this wiring is "tight", check the expander board.  Also see if they've installed a tamper switch for the cover door.  Make sure it's protruding enough to make the contact with the door closed.  And finally, check your keypad connections.  When you power down the system, pull out the wallwart first, then disconnect the battery.  With DSC the battery has to be connected first and then AC applied when you power back up.  You'll have to reset the system clock afterwards or you'll have a zone "8" trouble.  If you're still having problems, don't hesitate to give me a call.  1 888 340 3473 (Toll Free).

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Frank Kurz


Questions relating to Burglar Alarm and Security Equipment, Fire Alarm and Extinguishment Systems, Access Control, CCTV Systems, Installation, Service, Testing, Verification


30 years installing, servicing, and testing security, access control, extinguishment, and fire alarm systems

Chair of ULC Working Groups for Fire Alarm Testing (CAN/ULC-S536) and Fire Alarm Verification (CAN/ULC-S537), Executive Director of the Fire Protection Technicians Network (

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Associate in Science; Emergency Systems (University of British Columbia); Aircraft Maintenance Technology (BCIT)

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