Start with purpose, not a number
Packages of 4, 8 or 16 cameras are convenient, but the right number comes from listing what you need to see and how clearly. A wide camera over a car park shows that something happened; a camera at a doorway at head height shows who it was. Each camera should have one clear job.
Three questions for every area
- What do I need to know here: that someone was present, or exactly who they were?
- Where do people or vehicles have to pass? Entrances and gates are the most valuable positions.
- What lighting is there at night?
Typical starting points
- Villa or townhouse: main gate, front door, driveway or parking, back garden, and side passages if they give access.
- Apartment: the entrance door (check building rules first) and possibly the main living area if needed.
- Shop: entrance, cash point, sales floor and stockroom.
- Office: entrance and reception, corridors to secure rooms, server or records rooms.
- Warehouse: gates, loading bays, yard, racking aisles and the perimeter.
These are starting points; layouts, blind spots and lighting change the final count.
Common mistakes
- Mounting cameras too high, so you only see the tops of heads.
- Pointing cameras at bright openings, which turns people into silhouettes.
- Relying on one wide camera to do both overview and identification.
- Forgetting to leave spare recorder channels for future cameras.
Premises with formal requirements
For premises covered by SIRA’s Preventive System Manual, camera positions and view types are specified for each facility type, so the count follows from those requirements.