Intruder Alarm Systems for Commercial Premises
An intruder alarm that is not monitored, not maintained, and not connected to anything is just a noise maker. It might deter an opportunist. It will not deter a determined intruder. And if nobody is listening when it activates - no monitoring centre, no keyholder notification, no police response - then the siren sounds for 20 minutes, times out, and the building is left open.
A properly designed commercial intruder alarm is graded to the risk, installed to PD 6662 by an approved installer, connected to a professional alarm receiving centre for monitoring, registered with the police for a Unique Reference Number, and integrated with CCTV for visual verification of alarm activations. That is the difference between a system that protects your premises and one that just makes a noise.
Electrifire designs, installs and maintains intruder alarm systems for commercial premises across London, Kent and the M25 corridor. We install systems to BS EN 50131, connect them to NSI-approved alarm receiving centres for professional monitoring, and integrate them with CCTV so that alarm activations are visually verified before a police response is requested.
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BS EN 50131 Grade 2 and Grade 3 intruder alarm systems
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Professional monitoring through NSI-approved alarm receiving centres
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Police Unique Reference Number (URN) registration
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CCTV visual verification of alarm activations
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Integration with access control for automated arm/disarm
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False alarm management and reduction
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Wired and wireless systems for new builds and retrofits
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Intruder Alarm Design and Installation
Every commercial intruder alarm installation starts with a risk assessment. The risk assessment determines the grade of system required, the detection coverage needed, the signalling method, and the monitoring requirements. The grade reflects the level of risk and the sophistication of the likely intruder - from an opportunist trying a door handle to a determined attacker with knowledge of alarm systems and tools to defeat them.
Grade 2 is suitable for moderate-risk commercial premises where the intruder is expected to have some knowledge of alarm systems. This is the minimum grade typically accepted by commercial insurers and is appropriate for offices, retail units, workshops and smaller commercial buildings.
Grade 3 is required for higher-risk premises where the intruder is expected to be experienced with alarm systems and may carry tools to defeat them. Most insurance companies require Grade 3 where the alarm is a condition of insurance cover. This is the standard for warehouses, distribution centres, high-value retail, and premises with significant stock or equipment.
The system grade is determined by the risk assessment, and every component - control panel, detectors, signalling equipment - must meet the specified grade. A system is only as strong as its lowest-graded component.
Commercial intruder alarm systems use a combination of detection technologies depending on the building layout and the areas to be protected. PIR (passive infrared) detectors identify movement by detecting changes in infrared energy - the most common detector type for internal spaces. Dual-technology detectors combine PIR with microwave detection to reduce false alarms in challenging environments. Magnetic contacts protect doors and windows by detecting when they are opened. Vibration detectors identify attempts to break through walls, floors or ceilings. For perimeter protection, external beam detectors and fence-mounted detection provide early warning before an intruder reaches the building.
Wired intruder alarm systems use physical cabling between every detector and the control panel. They offer the highest reliability and are specified for new builds and major refurbishments where cabling can be installed during construction. Wireless systems use encrypted radio communication between detectors and the panel, making them suitable for occupied buildings, listed properties, and retrofit installations where running new cables is impractical or disruptive. Modern commercial wireless systems are fully compliant with PD 6662 and BS EN 50131, and are accepted by insurance companies at the same grades as wired systems.
Intruder Alarm Monitoring and Police Response
The Regulatory Reform (Fire Safety) Order 2005 requires the responsible person for any commercial premises to ensure fire alarm systems are adequately maintained. BS 5839-1:2025 recommends inspection and servicing by a competent person at least every six months, with weekly testing of manual call points carried out by the building's own staff. These are not optional recommendations; they are the baseline that enforcement authorities, fire risk assessors and insurers expect to see documented.
Electrifire provides planned preventative maintenance contracts that manage this for you. We schedule your service visits, attend when agreed, carry out a full inspection to BS 5839-1, and provide a detailed service report and signed logbook entry. If we find a problem, we tell you clearly what it is, what it means, and what it will cost to resolve.
When your intruder alarm activates, the control panel sends a signal to a professional alarm receiving centre (ARC). The ARC operator evaluates the signal, contacts the designated keyholders, and if the activation is confirmed as genuine, requests a police response. The entire process is designed to ensure that confirmed intrusions receive a rapid, prioritised response while false alarms are managed without wasting police resources.
Electrifire connects intruder alarm systems to NSI-approved alarm receiving centres operating to BS EN 50518. The same ARC can also monitor your fire alarm system, providing a single monitoring point for both fire and security. See our fire monitoring page.
Intruder alarm systems can be integrated with access control so that the alarm is automatically armed when the last person leaves the building (detected by the access control system) and disarmed when the first authorised person arrives. This eliminates the risk of human error - forgetting to set the alarm, entering the wrong code, or failing to arm specific zones. It also creates a complete audit trail of arm/disarm events linked to individual users. See our access control page.
Police Response and URN Registration
Police response is not automatic. Under the NPCC (National Police Chiefs' Council) policy, police will only respond to intruder alarms that are installed by an NSI or SSAIB-approved company, registered with a valid Unique Reference Number (URN), and operating a confirmed alarm system to BS 8243. A confirmed alarm requires two separate activations within a defined time window before the ARC contacts the police - this is the mechanism that filters out false alarms and ensures police resources are directed to genuine intrusions.
If your system generates three false alarm police attendances within a rolling 12-month period, your URN can be downgraded to Level 3 (no police response). This means the police will not attend your premises regardless of what the alarm does, until the system is brought back into compliance. Your insurance company must be notified if this happens, and your cover may be affected.
Intruder Alarm Maintenance and False Alarm Management
Police response intruder alarm systems require a minimum of two maintenance visits per year under BS 9263. Each visit includes functional testing of all detectors, the control panel, signalling equipment, sounders, power supplies and battery backups. The engineer verifies that the system is communicating correctly with the ARC and that the confirmed alarm mechanism is operating as designed. A service report is issued for the fire logbook and insurance compliance records.
For premises managed in accordance with SFG20 building maintenance standards, intruder alarm servicing aligns with the security system tasks specified in that framework.
False alarms are the single biggest threat to your police response capability. Three false alarm police attendances in 12 months and your URN is downgraded. Beyond the police response issue, false alarms disrupt your business, erode confidence in the system, and waste keyholder time.
The most common causes of false alarms in commercial intruder systems are poorly positioned detectors (triggering on heating systems, moving signage, or wildlife), failing components that have not been maintained, incorrect system configuration, user error during arm/disarm, and environmental factors such as draughts or temperature changes. Electrifire addresses false alarms systematically - identifying the root cause through event log analysis, adjusting detector positions or sensitivity where needed, replacing degraded components, and retraining users where the cause is procedural rather than technical.
If you have an existing intruder alarm system installed by another company, we can inspect it, verify its grade and compliance status, check whether it has a valid URN, and bring it into a planned maintenance schedule. Where the system is non-compliant, unmonitored, or generating persistent false alarms, we can advise on the most practical remediation path - whether that is repair, reconfiguration, partial upgrade, or full replacement.
Intruder alarm maintenance can be incorporated into your wider planned maintenance contract covering fire alarms, CCTV, access control and passive fire. See our planned maintenance page.
Frequently Asked Questions
Most commercial premises require a Grade 2 or Grade 3 system under BS EN 50131. Grade 2 is suitable for moderate-risk premises such as offices and smaller retail units. Grade 3 is required for higher-risk premises and is the standard most insurance companies require where the alarm is a condition of cover. The appropriate grade is determined by a risk assessment carried out during the site survey.
Police response requires the system to be installed by an NSI or SSAIB-approved company to PD 6662, connected to a professional alarm receiving centre, registered with a valid Unique Reference Number (URN), and operating a confirmed alarm mechanism to BS 8243. Additionally, many police forces now require CCTV visual verification before they will dispatch officers.
Under the NPCC policy, three false alarm police attendances within a rolling 12-month period can result in your URN being downgraded to Level 3, which means no police response. Your insurance company must be notified, and your cover may be affected. Proper system design, regular maintenance and false alarm investigation are essential to protecting your police response capability.
Many commercial insurance policies require an intruder alarm installed and maintained to a specific grade by an NSI or SSAIB-approved company, with professional monitoring through an approved ARC. Check your policy schedule for specific requirements. An intruder alarm that does not meet your insurer's requirements may invalidate your cover in the event of a claim.
Yes, and increasingly they should be. When integrated, an intruder alarm activation automatically triggers the relevant CCTV cameras, allowing the ARC operator to visually verify the event. Many police forces now require visual verification before dispatching officers. Without CCTV integration, your alarm may not receive a police response even with a valid URN. See our CCTV page.
Yes. When integrated with access control, the intruder alarm can arm automatically when the last person leaves the building and disarm when the first authorised person arrives. This eliminates human error and creates a complete audit trail of arm/disarm events. See our access control page.
Police response systems require a minimum of two maintenance visits per year under BS 9263. Each visit includes functional testing of all detectors, the control panel, signalling equipment, sounders, power supplies and battery backups. Servicing can be combined with your fire alarm and CCTV maintenance under a single planned maintenance contract. See our planned maintenance page.
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