What each system actually does
An intruder alarm is a sensor-based detection system — PIRs, door contacts, glass-break and shock sensors — wired or wireless, signalled to a control panel and (when monitored) to an alarm receiving centre.
Monitored CCTV is an analytics-driven camera system continuously reviewed (or event-triggered) by operators at a central monitoring station. Detection comes from video analytics; verification comes from a trained operator looking at the scene.
How well each detects a real intrusion
Intruder alarms detect with very high reliability inside a building — a door opens, a sensor triggers. Outside, performance depends on the chosen technology (beams, externally rated PIRs, vibration) and is much harder to tune.
Monitored CCTV detects in open environments — yards, perimeters, large open buildings — using human/vehicle classification. It will not, by itself, detect an attack from a route the cameras don't cover.
What happens when the system triggers
An intruder alarm alert is, by default, an unverified event. Police response in most jurisdictions requires sequential confirmation or video verification — otherwise keyholder or guard response is the realistic outcome.
Monitored CCTV provides verification by design. An operator sees the event, audio-warns the intruder live, and escalates to police with verified intent — typically receiving a much higher response priority.
False-alarm performance
Modern wireless alarms have very low false-alarm rates indoors. External alarm zones — especially PIR-based — are much more variable.
Modern analytics-driven CCTV running human/vehicle classification has dramatically lower false-alarm volumes than legacy pixel-motion systems, but tuning quality matters significantly.
Capital vs running cost
Intruder alarm systems typically have lower install cost and a small monthly monitoring fee. Replacement and maintenance over a decade is modest.
Monitored CCTV has higher up-front and recurring cost — cameras, lighting, network, ARC fees — but delivers an active response capability that an alarm alone cannot.
When to use both
On commercial sites with assets inside a building and activity outside, intruder alarms and monitored CCTV are complementary. Alarms cover interior detection and verification; CCTV covers perimeter, yard and approach.
On remote, low-occupancy or perimeter-driven sites — solar, construction, vacant — monitored CCTV is increasingly the primary detection system, with alarms used selectively where structures exist.
Intruder alarm vs CCTV monitoring at a glance
Both technologies have a clear role. The right answer depends on what you're protecting, where, and what response you need.
| Feature | Intruder alarm | Monitored CCTV |
|---|---|---|
| Detection method | Fixed sensors (PIR, contacts, shock) | Analytics-driven cameras + operator verification |
| Best coverage | Inside buildings | Perimeters, yards, open sites |
| Response pathway | Keyholder, guard, or police with confirmation | Verified police response with operator-witnessed intent |
| Live deterrence | Sounder / strobe only | Audio challenge, recorded escalation, live operator |
| False-alarm performance | Excellent indoors, variable outdoors | Strong with tuned AI classification |
| Capital cost | Lower | Higher |
| Recurring cost | Low monthly ARC fee | Higher ARC + bandwidth + lighting |
| Typical lifespan | 8-12 years | 6-10 years per camera generation |
Which should you choose?
On most commercial premises with a clear building envelope, an intruder alarm with monitoring remains the cost-effective baseline. Where the asset is the site itself — yards, plant, stock outside — monitored CCTV is the stronger primary detection layer.
- Discrete building envelope with definable entry points
- Predictable occupancy patterns and keyholders
- Lower-value or low-target external footprint
- Tight capital budget
- Open, perimeter-driven or remote site
- High-value outdoor assets (plant, stock, vehicles)
- Need verified police response on intent
- Active deterrence and audio challenge required
Frequently asked questions
Can monitored CCTV replace an intruder alarm?
On many commercial sites, yes — particularly remote or perimeter-driven ones. On premises with valuable internal assets it's usually safer to keep both, with monitored CCTV providing verification and external deterrence.
Does CCTV monitoring guarantee a police response?
It significantly improves the likelihood and priority of police response by providing operator-verified intent at the moment of the call. Local policy still applies.
Which has lower false alarms?
Modern intruder alarms indoors are extremely reliable. Outdoors, tuned analytics-driven CCTV typically outperforms external PIR-based alarm zones.
Do insurers prefer one over the other?
Insurers set minimum requirements per premises class, and an intruder alarm to the specified grade is almost always the baseline requirement. Monitored CCTV is increasingly required as a supplementary layer for higher-value premises or for perimeter risk. The two are complementary in most insurance schedules rather than mutually exclusive alternatives on any given commercial site.
Which is faster to install?
Wireless intruder alarms typically install in days on a mid-sized commercial site. Monitored CCTV installations are longer — one to three weeks — because they involve camera mounting, cabling or wireless mesh, network integration and analytics tuning. Redeployable CCTV towers are the exception, deploying in hours for short-term or interim protection on open commercial premises.
Can one supplier deliver both?
Most reputable commercial security installers deliver both, and there are real operational advantages to a single accountable supplier — unified maintenance, integrated monitoring contract, one escalation path. The trade-off is reduced competitive pressure on pricing and potentially weaker specialisation in one discipline or the other, which specifiers should evaluate on the specific supplier rather than assume as a category rule.
How do lifecycle costs compare?
Over ten years, an intruder alarm system typically costs less than half the equivalent monitored CCTV deployment on the same site — driven by lower capital, lower monitoring fees and simpler maintenance. Monitored CCTV delivers materially more operational capability at that higher cost. The correct comparison is against risk reduction, not headline cost, on any specific site.
Talk through this comparison with a specialist
Tell us about your site and we'll match the comparison to your actual constraints — risk profile, budget, response model and lifecycle.