When Alarm System Installs Go Wrong

…people die.

Failures here, in short:
– People using a smoke detector type that doesn’t detect smouldering fires
– Alarm systems that detect phone lines being cut… unless the house uses a VoIP-based “virtual phone line”
– Acoustic glass break sensors not installed line-of-sight to the glass, so it doesn’t pick up the ultrasound energy indicative of breaking glass
– Motion sensors wired up wrong, so they don’t set off an alarm when they’re supposed to

Fundamental failure: complex system where something could go wrong, so it did.

Iterative security, where you red-team and improve, is better. At least then you get to learn. But even that can fall victim to a smarter red team.


“Amanda had thought she was doing everything correctly as she tested her store-bought smoke detectors regularly and changed the batteries faithfully. However, when a fire broke out in her home, the smoke detectors did not sense it as expected. Amanda could do nothing more than watch in horror as all of her children died in the blaze.

What could have been done to lessen the likelihood of this terrible incident? As you may have already guessed, Amanda had installed commonly available ionization smoke detectors. As you may also know, these devices have been shown to be considerably insensitive to smoldering type fires. In this case, a photoelectric smoke detector would have given earlier warning of the fire. Better yet, the installation of a dual technology smoke detector would have covered a more complete spectrum of smoke and fire detection.[…]

Communications Failure — In the design of the alarm system it was anticipated the intruder would try cutting the alarm phone line. The phone line battery voltage was to be monitored by the alarm panel and send an alarm out over cellular communications while activating local keypad alarm annunciation. However, the phone system in the house was communicating via VoIP and not POTS. When the exterior cable was cut it had no relationship to internal house phone system battery voltage being maintained by the network phone modem.

The alarm panel never sensed the exterior network communication cable being cut and could not sound even a local alarm. It was apparent that the alarm company staff did not understand the different types of alarm communications connectivity. Additionally, the cellular backup unit was also not installed properly and, according to court documents, the installing technician testified he had never installed this configuration before.

From my training experience, I know it is instinctive for technicians not to admit they don’t know certain technical skills. However, it is imperative you instill in your staff to ask when they do not know how to do a particular task.

Glass-break Does Not Perform — An acoustical glass-break (AGB) detector was designed and located in the basement area. However, during the installation the technician did not locate the AGB as specified in the design. The device was not in proper line-of-sight of the protected glass and neither the customer nor alarm company staff was informed of the change made by the technician. The AGB did not activate the alarm when the intruder broke the glass. This is another example of a lack of training and procedural protocol.

Motion Detectors Malfunction — Two motion detectors, one in the basement and another on first floor, had been installed improperly. The design was to have the basement unit activated when the woman was at home and had armed her alarm system in the night-stay mode. The motion sensors were not on separate zones and did not work effectively in the night-stay mode. The alarm did not happen and consequently the woman and her current boyfriend were killed in her second-story bedroom.”

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