Office intruder alarm, Ostadsara, Rasht

The brief

A ground-floor office with windows onto the alley whose old alarm had gone off for no reason several times, to the neighbours’ annoyance, so the owner had stopped setting it. The aim was a system that would not false-alarm and would keep working through power cuts.

How it was done

1. 01 Cause of the earlier false alarms found: motion sensors facing a sunny window and the air conditioner
2. 02 Motion sensors repositioned away from heat sources and airflow
3. 03 Magnetic contacts fitted to the door and alley-facing windows
4. 04 Sensors split into five zones so the alarm report shows where it was triggered
5. 05 Backup battery sized for summer power-cut hours
6. 06 Every zone and the phone call-out tested with the owner present

The outcome

The system is set every night and has not false-alarmed since installation. It stays armed through power cuts and reports the outage by phone.