Perimeter protection: fences, detection and response

• Deter: a visible fence, lighting, signs and a security presence make the target look hard, so nobody tries.
• Detect: sensors and cameras pick up the attempt while it is happening, not the next morning.
• Delay: fences, gates, locks and distance keep the intruder out long enough for the response to arrive.
• Respond: a person checks what is going on and acts, following a plan written in advance.

The rule that holds a perimeter together: the delay must last longer than the response takes to arrive. If the fence can be crossed faster than anyone can get there, detection just records the theft.

OVIT designs the perimeter in five layers: risk assessment, physical delay, early detection, verification and response, and evidence and improvement (security systems).

• On the fence: sensors that notice someone climbing, cutting or lifting the mesh. They work well when the fence is in good repair and rigid.
• In open ground: invisible beams or zones that alert when someone crosses a line or enters a strip. They need clear, level ground without vegetation that moves.
• By video: cameras with video analytics that tell a person or vehicle from other movement, and cameras that see in the dark. They also give you verification: the operator sees what triggered the alarm.

Every type has its own nuisance alarms: wind, rain, animals, branches. That is why critical stretches combine two technologies and an alarm is verified on video before anyone is sent. If cameras see beyond your boundary, read the CCTV and GDPR guide.

• Light the boundary and the strip in front of it, so anyone approaching is visible while the guard is less exposed.
• Avoid lights that dazzle cameras or throw deep shadows beside gates and corners.
• Motion-activated lighting draws attention and warns, but it has to be tied to someone who will look.
• Check for failed lamps regularly: a dark stretch is exactly where someone will choose to cross.

• Access control: who is allowed through, at what times, with every passage logged.
• State: the gate or barrier must report when it stays open longer than expected.
• Fail-safe behaviour: what the gate does if the power fails or the mechanism breaks is decided at design time, not on the night it happens.
• A camera on the gate: an image of the vehicle and driver for every out-of-hours passage.

In OVIT security systems, barriers, gates and doors are wired into the same response model as the rest of the site, with clear fail-safe behaviour.

1. Alert: the alarm reaches someone awake and on duty, not an owner’s phone.
2. Verify: the operator looks at the zone on camera and decides whether it is a person, an animal or the weather.
3. Dispatch: if it is real, the guard or patrol goes, by a known route and with instructions for their own safety.
4. Escalate: when the police are called, and who tells the client.
5. Record: what happened, when, and what changes on the perimeter so it does not happen again.

These instructions belong in the post orders. If the site has no permanent guard, the static guarding vs mobile patrols guide explains how the response gets there.

• A fence that delays, but nobody knows someone is crossing it.
• Vegetation, containers or materials stacked against the fence that turn into a ladder.
• Nuisance alarms that are never investigated, until the operator starts ignoring them.
• A gate left open for the convenience of suppliers.
• A system tested device by device, but never along the whole path from the sensor to the person who goes.

If you put cameras on the perimeter, the Greek DPA’s Directive 1/2011 requires clearly visible signs before anyone enters their field of view (article 12).