Glossary
Electric fence & perimeter terms
The vocabulary used in specifications, tender documents and installation drawings.
- Terms
- 24
Control & integration
- Alarm zone
- The smallest segment of perimeter that reports its own alarm. Zone size is set by the response plan: how far a guard can travel and still verify the event.
- Dry contact
- A relay output that provides a voltage-free open/closed signal. It is the most universal interface between a sensor and a third-party alarm panel or camera input.
- False alarm / nuisance alarm
- An alarm triggered by something other than the threat the system was designed to detect: wind, animals, vegetation, maintenance work or a failing component. The cause should be fixed, not only the sensitivity lowered.
- Fence host
- The energizer and controller for a pulse or tension fence. It generates the pulse or reads the tension module, reports alarms and provides relay or network outputs.
- NB-IoT
- Narrowband Internet of Things: a low-power cellular standard for small data messages. Used for remote perimeter barriers where no cable route exists.
- RS485
- A differential serial bus used for daisy-chained devices over twisted-pair cable. Common in perimeter hosts and control keyboards; it does not support star wiring.
- Zone map
- A site plan showing every zone boundary, name, device address, camera preset and response route. It is a controlled document, not a one-off drawing.
Detection
- Alloy wire
- The magnesium-aluminium wire strung between fence posts in a pulse fence. Typical specification is φ0.66 mm × 7 strands, chosen for oxidation resistance and low conductivity.
- Bi-polar pulse
- A pulse fence arrangement in which adjacent wires sit at different potentials. A jumper across two wires creates a short circuit instead of silently equalising the line.
- Buried leakage cable
- Two parallel cables buried a few centimetres below the surface that create an electromagnetic field. A person crossing the field disturbs it and triggers the detector.
- DTS (distributed temperature sensing)
- A fibre-optic technique that measures temperature continuously along a cable, used for cable trays, tunnels and conveyors. It measures heat, not motion.
- Fibre interferometer
- A sensing method that detects vibration by measuring changes in the interference pattern of light travelling through a fibre. Used in vibration and locating fibre systems.
- Laser barrier
- A transmitter and receiver pair using a narrow laser beam. A person interrupting the beam triggers an alarm. Range and beam count depend on the model.
- Leakage cable
- A coaxial cable designed to radiate a controlled electromagnetic field. Used in buried detection, where two cables form a sensing field above the ground.
- PIR (passive infrared)
- A detector that senses changes in infrared radiation caused by a moving body. Often combined with microwave in a dual-technology detector to reduce false alarms.
- Pulse duration
- The length of one high-voltage pulse, typically ≤0.1 s for an electronic fence. Short duration is a safety feature; it limits the energy delivered to a contact.
- Pulse energy
- The charge delivered in one pulse, often expressed in millicoulombs (mC). It is a better safety indicator than voltage alone; a fence catalog may list ≤2.5 mC.
- Tension fence
- A fence whose wires are held under tension and connected to a strain module. Climbing, lifting or cutting changes the tension and triggers an alarm. No voltage on the fence.
- Vibration fibre
- A fibre-optic sensing system that detects vibration along a cable bonded to a fence, wall or ground. It can report a zone, or a position with a locating processor.
Compliance
- Ex d
- Flameproof protection: the enclosure contains an internal explosion and prevents it from propagating to the surrounding atmosphere. Common marking for hazardous-area detectors.
- Ex ib
- Intrinsic safety with two independent faults considered. The circuit energy is limited so that it cannot ignite the surrounding atmosphere, even under fault conditions.
Installation
- IP rating
- Ingress protection: the first digit is dust, the second is water. IP65 is dust-tight and protected against water jets; IP66 adds protection against powerful jets.
- Sterile zone
- A clear strip between two perimeter layers where nothing is stored and vegetation is controlled. It gives the inner sensor a clean detection field and the guard a safe inspection area.
- Terminal post
- The post at the end of a fence zone or at a corner that takes the full wire tension. Terminal posts are usually no more than 100 m apart in a pulse fence.
From metres to energizer
Send the line length. We will return the electric fence price per metre and the energizer selection.
Tell us the perimeter metres, wall or fence type, number of gates and the alarm response. We will size the electric fence energizer, price the wire, insulators and tensioners by the metre, and include the electric fence installation notes.