Want the alarm to go off before anyone reaches a door? Here is how beams and outdoor detectors work, where they go on a landed house, and how to stop false alarms.
Perimeter and outdoor sensors raise the alarm while an intruder is still outside: on the fence, in the garden or at the porch, before a door or window is touched. The main types are active infrared beams that run along a wall or fence line, outdoor motion detectors that watch a zone such as the driveway, and sensors fitted to gates and grilles. Outdoors, the hard part is not detecting people but ignoring cats, birds, swaying plants, rain and sun, so placement and the choice of sensor matter more than the brand. Our home alarm guide lists one reseller's outdoor motion detector at RM785 per sensor and a professionally installed 16-zone wired panel package at RM1,899 – RM2,399.
Most home alarms watch doors and windows and the rooms inside. By the time they trigger, someone is already breaking in. Perimeter and outdoor sensors add an earlier layer: they notice someone climbing the wall, crossing the garden or standing at the back door, which gives time for lights, a siren or a phone alert to act before any damage is done.
They work best as one layer of several, alongside good locks and grilles, outdoor lighting and cameras. Our home alarm system guide explains how the panel, sensors and siren fit together.
| Sensor | How it detects | Best for | Watch out for |
|---|---|---|---|
| Active infrared beam (transmitter and receiver) | An invisible beam between two units; the alarm triggers when it is broken | Straight fence or wall lines, side passages, the top of a boundary wall | Needs a clear, straight line; plants, washing lines and misalignment |
| Outdoor motion detector | Detects movement and body heat in a zone | Driveway, porch, back yard, gate area | Pets, moving plants, sun and passing traffic in view |
| Gate and grille contacts | A magnetic contact opens when the gate or grille moves | Main gate, side gates, grille doors | Gates that rattle in wind or are left ajar |
| Fence-mounted vibration sensors | Detect climbing or cutting on the fence itself | Metal fences and railings | Wind, traffic vibration and loose panels |
A beam sensor is a pair of units facing each other: one sends an invisible infrared beam, the other receives it. When something breaks the beam, the receiver signals the alarm panel. Many units send more than one beam and only trigger when several are broken at the same moment, which helps them ignore a falling leaf or a bird flying through while still catching a person.
Outdoor motion detectors are weatherproofed versions of the indoor detectors. They watch an area rather than a line, which suits driveways, porches and back yards. The skill is in pointing them so they see where a person would walk but not the road, the neighbour's garden, trees or a spot where the sun hits hard. Many models combine two detection methods and only trigger when both agree, and some are designed to ignore small pets. Our outdoor security lighting guide covers motion-sensor lights, which are often paired with these detectors.
An outdoor alarm that goes off every night for a cat is worse than none, because the household stops trusting it and switches it off. The fixes are mostly about placement and settings:
Put each outdoor area on its own zone. When the alarm triggers, knowing it was the back wall rather than the front gate tells you what to check, and makes camera footage quicker to find.
Wired sensors are cabled back to the panel, so they need no batteries and are hard to jam, but cabling across a garden or along a boundary wall means trenching or conduit. Wireless outdoor sensors are faster to install on a finished house but depend on batteries and a good radio link. The home alarm guide on this site notes that a purely wired panel with hard-wired sensors needs no MCMC label, while a wireless hub or any sensor that talks to its hub by radio is very likely inside MCMC's certification scheme, so check the label on wireless parts.
Decide the response before the sensors go up. Outdoor zones can sound the siren, switch on floodlights, send a phone alert, or all three. Many households set outdoor zones to alert only at night or when the system is armed away, and to trigger lights first. Pairing a beam zone with a camera covering the same stretch lets you check an alert on your phone before reacting. Our CCTV installation guide explains camera coverage.
Our home alarm guide publishes shelf prices from single resellers rather than a market average, and a professionally installed wired package. These are the relevant lines (2026, Malaysia).
| Item | Published price | Source guide |
|---|---|---|
| Outdoor motion detector (one reseller's shelf price) | RM785 per sensor | Home alarm system guide |
| Wireless external siren (one reseller's shelf price) | RM895 per unit | Home alarm system guide |
| GSM communicator module | RM1,000 per unit | Home alarm system guide |
| 16-zone wired panel package, wiring and installation included | RM1,899 – RM2,399 per system | Home alarm system guide |
WhatsApp us your job details for a quote — we reply within the hour.
💬 WhatsApp for a quoteBeam sensors are not priced on our guides; they are quoted with the layout, because the number of pairs and the cabling route decide the cost.
Perimeter and outdoor sensor jobs are quoted case by case. WhatsApp us your job details for a quote: the house type, which sides you want covered, whether you have an existing alarm panel, and whether you prefer wired or wireless. We reply within the hour, the price we agree is a flat price with no hidden charges, and a site visit is RM150, waived if you go ahead.
How we estimated prices: every RM figure on this page is quoted unchanged from the ClickBina guides named above, which publish them as single-seller prices for 2026, not fixed rates.
WhatsApp us your job details for a quote — we reply within the hour.
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