“How many cameras do we need?” is the first question every estate committee asks. The honest answer is that the number comes last. It falls out of three earlier decisions: what each camera must be able to see, where the risks are, and how long you need to keep the footage.
Start with what each camera must do
A camera that shows “someone walked past” is very different from one that shows a face you can identify in court. The European standard for video surveillance (EN 62676-4) gives four levels, measured in pixels per metre of the scene:
- Detect (about 25 px/m): you can tell that a person or vehicle is there.
- Observe (about 62 px/m): you can see what they are doing and what they are wearing.
- Recognise (about 125 px/m): you can tell whether it is someone you know.
- Identify (about 250 px/m): you can identify a stranger beyond reasonable doubt.
The higher the level, the narrower the area one camera can cover. A single 4MP camera might watch a whole car park at “detect” level, but only a gate lane a few metres wide at “identify” level. That is why the zone objective decides the camera count, not the size of the estate.
Map the estate by risk, not by plot
We do not count cameras per house. We walk the estate and mark the places where something happens:
- Gates and entrances. Every person and vehicle passes here, so these get the highest level: identify for faces, and plate-recognition (ANPR) cameras for vehicles where the budget allows.
- The perimeter. Fences and walls need detection along their whole length. Wide-angle, thermal or analytics cameras with line-crossing alerts work well here, because they tell the guard when someone climbs, not just record it.
- Road junctions. Cameras at junctions show which way people went after the gate, which is often what an investigation needs.
- Shared spaces. Parks, the clubhouse, the generator house, water tanks and the estate office.
- Blind spots. Corners where the wall bends, areas behind buildings, and drainage channels that can be used as a way in.
The infrastructure matters as much as the cameras
Estates are big, and ordinary network cable only runs about 100 metres. A reliable estate system usually needs:
- A fibre backbone linking distribution points around the estate.
- Distribution cabinets with PoE switches, each with surge protection and UPS backup.
- A control room at the gate or estate office with the recorder and screens.
- A separate network for the cameras, so residents’ Wi-Fi and the security system do not affect each other.
Size the storage properly
Recording space is calculated, not guessed. The basic sum is: bitrate × seconds per day × days to keep, for every camera.
As an example, a 4MP camera recording at about 2 megabits per second with H.265 compression uses roughly 20 GB a day. Thirty days of recording is about 650 GB for that one camera. Multiply by the number of cameras and you can see why recorders are often under-sized. Most estates keep 30 days; some keep 14 to save cost, or 60 for higher-risk areas.
So what is the number?
For a typical estate, the gates usually take 2 to 4 cameras each, the perimeter takes one camera for every stretch of wall it can cover at detection level, and each important junction or shared space takes one or two more. The total depends on the layout, but this method gives a number you can defend to residents and check against the drawings.
How we do it
We survey the estate, mark every camera on the layout drawing with its purpose and field of view, and produce a camera schedule, cable schedule, power budget and storage calculation before we quote. Your committee gets a design it can question line by line, not just a price.
