This article was machine-translated from French and is being reviewed. Prices are in Algerian dinars excl. VAT.
The placement of alarm detectors follows a simple rule. First protect the access points: doors, windows, metal shutters. Then cover the path an intruder would take to reach the cash register, stock or server. Place the siren where it alerts and deters. Put the control panel in a central, closed, low‑visibility spot. Poor placement creates blind spots and false alarms.
In short
- First access: a door/window opening detector on each exposed door and window, then motion detectors along the intruder’s path.
- Motion detector: mounted high, at an angle, aimed at the zone to cover. Never face the sun or a vent.
- Outdoor siren on the façade, out of range. Indoor siren audible everywhere. Control panel in a closed room, at the center.
Alarm detector placement: think in zones
Divide the room into zones: entrance, sales or office area, storage or technical room, exterior. Protect each zone with two layers. The perimeter groups door and window opening detectors. The volume groups motion detectors. The perimeter alerts before the intruder enters. The volume takes over if already inside.
Plan two armament modes: “absence” (fully armed) and “presence” (perimeter only). The detector placed on the path between the front door and the remote or keyboard must have an entry delay. Otherwise, the siren triggers on every entrance. See how to avoid false alarms.
Motion detectors: height and angle
- Height. Mount the detector high, generally 2 to 2.5 m from the floor, or at the height indicated on the manufacturer’s datasheet.
- Angle. Place it in a corner of the room, facing the area to cover. A passive infrared motion detector sees better a person crossing its field than one moving straight toward it. Range and detection angle are listed on its datasheet.
- Avoid. A sunny window, an air conditioner, a radiator, a fan, a shelf or curtain in front of the device, a vibrating mount.
- Display or window. A curtain detector covers an opening on a narrow plane. Example: the Ajax MotionProtect Curtain, at 13,000 DA HT (price from the AsloTech store as of 06/11/2026, subject to availability).
Doors and windows
An opening detector has two parts. Mount the electronic part on the fixed frame and the magnet on the door leaf. Align them, respecting the maximum gap prescribed by the manufacturer. A metal curtain requires a detector or contact designed for metal: an ordinary opening detector may malfunction on steel. Check its datasheet before buying.
For a window accessible from the street, use an opening detector or a glass break detector. The store lists the Ajax GlassProtect at 9,500 DA HT. It does not list a Dahua glass break detector.
Siren and control panel
Outdoor siren. Mount it on the façade, high, out of reach without a ladder, visible from the street and sheltered from direct sun and rain. It alerts neighbors and deters. The Dahua ARA13-W2 costs 18,000 DA HT. The Ajax StreetSiren costs 32,000 DA HT.
Indoor siren. Mount it centrally, audible throughout the room. The Dahua ARA12-W2 costs 11,000 DA HT. No Ajax indoor siren is listed in the quote.
Control panel. Place it in a closed room, low visibility, at the center of the radio area. Keep it away from the entrance: an intruder should not find it in a few seconds. Keep a protected outlet and router access. Before installing a detector, check its signal level in the app. If the signal is weak, move the device or add a Dahua ARA43-W2 repeater for 29,000 DA HT.
Three examples: online shop, office, warehouse
| Room | Door‑opening detectors | Motion detectors | Siren | Central unit |
|---|---|---|---|---|
| Online shop (sales room and storage) | Entrance door, service door, curtain | One in the room, opposite the entrance. One in storage | Exterior on façade. Interior in the room | Closed storage, elevated |
| Office | Entrance door, ground‑floor windows | Access corridor, vault or server room | Interior in the corridor. Exterior optional | Closed room near the router |
| Warehouse | Dock doors, small gates | Walkways between shelves to avoid blind spots. Under a high ceiling, a detector mounted too high loses sensitivity: choose a model designed for that height. | Exterior, more interior audible throughout the hall | Closed office in the centre, repeater if range is low |
For a large warehouse, wired connection may be preferable over long distances: see wired or wireless alarm.
Frequently asked questions
How many motion detectors are needed?
One per zone to cover, rather than a fixed number. It depends on the room shape and furnishings. The technician maps each detector’s field on the plan during the visit. For budgeting, see the price of an alarm for a shop.
Is an exterior siren and an interior siren required?
They have two roles. The exterior alerts the street and deters. The interior warns occupants and annoys intruders. If budget is limited, the choice depends on the room and neighbourhood.
Can I move a detector myself?
Wireless, it is possible, but redo a walk‑through test and check the radio signal. A detector poorly reinstalled is a common cause of false alarms.
AsloTech holds type I license no. 207 dated 17 March 2025 from the Ministry of Interior (license scope). For a placement plan in your premises, request a visit: discover our intrusion and fire alarm solution or the alarm and fire category in the store.