Enterprise Intrusion Alarm System Design Guide: Zone Planning, Sensor Selection & CMS Integration

Executive Summary

An intrusion alarm system is your fastest-response security layer — detecting and communicating unauthorised entry within seconds, triggering a chain of response events that can intercept threats in progress. Designed correctly, an intrusion alarm system provides both deterrence and detection. Designed incorrectly, it generates so many false alarms that staff learn to ignore it, eliminating both functions entirely.

This guide provides the engineering methodology for designing enterprise intrusion alarm systems for commercial, industrial, and financial facilities in Bangladesh. We cover risk assessment, zone planning, perimeter and interior detector selection, alarm panel specification, communication path design, CCTV and access control integration, EN 50131 compliance, and commissioning protocol.

Bangladesh's intrusion alarm market is underserved by professional design. Many installed systems use inadequate zone planning, wrong detector types for their environments, and single-path communication that fails silently when the telecommunications link is cut. This guide addresses every one of these design failures, providing the framework for a system that performs reliably when it matters most.

Chapter 1: Risk Assessment for Intrusion

1.1 Threat Profiling

The starting point for intrusion alarm design is the same as for all security system design: defining the threats you face. Intrusion threats vary significantly by facility type, location, and operational profile.

For a bank branch in Dhaka's Motijheel area, the primary intrusion threat is after-hours break-in targeting cash storage — most likely occurring between 11 PM and 4 AM when foot traffic is minimal and response times are longest. The secondary threat is daytime robbery during business hours, addressed by panic alarms and CCTV rather than intrusion detection.

For a garment factory in Gazipur, the primary intrusion threat is after-hours cargo theft from finished goods storage — high-value, portable items that can be sold rapidly. Secondary threats include equipment theft (power tools, machinery components) and arson (a specific risk in the RMG sector).

For a commercial office building in Gulshan, the primary intrusion threat is after-hours entry targeting computer equipment, portable valuables, and data (physical document theft, hard drive removal). The threat profile here includes the risk of sophisticated attackers who may research the building's security systems before attempting entry.

Document your threat profile including estimated frequency of occurrence (how often per year similar facilities in your area are targeted), likely attack vectors (which entry points are most vulnerable), and likely attack timing (time of day, day of week). This profile drives zone priority, detection layer depth, and communication path redundancy.

1.2 Vulnerability Assessment

Walk every potential entry point with a security mindset: if you were attempting to enter this building without authorisation, how would you do it? Common vulnerabilities in Bangladesh commercial buildings:

• Ground-floor windows with inadequate glass (can be cut or broken without detection)
• Roof access doors — often unlocked, rarely alarmed, and accessible from adjacent buildings
• Service entrances and loading docks — lower security than main entrances, often with inadequate CCTV
• False ceilings connecting adjacent tenancies in multi-tenant buildings
• Basement car park entrances with poor lighting and inadequate access control

Map every vulnerability to the alarm zone that will protect it, and confirm that the alarm zone activation is detectable within the required response time.

Chapter 2: Zone Planning

2.1 Zone Types

An alarm zone is a logical grouping of detectors that report together to the alarm panel as a single circuit. Zone typing defines how the panel responds to that zone's alarm state:

Instant zone: Any activation triggers an immediate alarm. Used for inner-room detectors where any motion indicates an intruder already inside the building — there is no legitimate reason a motion detector in the vault room should trigger during an armed period, so no entry/exit delay is appropriate.

Entry/Exit delay zone: The first zone in the entry route is configured with an entry delay (typically 30–45 seconds) allowing an authorised user to enter and disarm the system before the alarm sounds. Exit delays allow the user to leave after arming. Entry/exit delay zones must be physically separate from instant zones.

Perimeter zone: Detects immediately if a door or window contact is broken while the system is armed. No delay — an opened window or forced door requires an immediate response.

24-hour zone: Always active, regardless of whether the system is armed or disarmed. Used for panic buttons, tamper detection, and fire zone inputs to the intruder panel. A panic button on a 24-hour zone activates even during normal business hours.

Fire zone: Connects the intruder panel to the fire detection system, enabling a unified alarm output. Note: dedicated fire alarm systems are preferred over using the intruder panel as the fire detection interface for any significant fire risk — the intruder panel's fire zone is typically a supplement, not a replacement.

2.2 Zone Numbering Methodology

Assign zone numbers logically to facilitate fast identification during alarm events. Use a structured numbering scheme:

• Zones 001–020: Ground floor perimeter (windows, doors)
• Zones 021–040: Ground floor interior (PIR detectors)
• Zones 041–060: First floor perimeter
• Zones 061–080: First floor interior
• Zones 081–100: High-security areas (vault, server room, cash counting)
• Zones 101–120: 24-hour zones (panic, tamper)

When an alarm activates zone 087 ("Server Room East Wall PIR"), the monitoring station operator immediately knows the location and zone type without needing to look it up. This reduces response time and increases the accuracy of initial dispatch decisions.

Chapter 3: Perimeter Detection

3.1 Door Contacts

Door contacts (also called magnetic contacts or reed switch contacts) are the simplest and most reliable intrusion detection device. A magnet is mounted on the door leaf; a reed switch contact is mounted on the door frame. When the door is closed, the magnet holds the reed switch in its normal state. When the door opens (moving the magnet away from the switch), the circuit changes state and the panel records the zone activation.

Surface-mount contacts are visible (door frame and door leaf each have a component) and easy to install but are vulnerable to defeat by a magnet held near the contact during opening. Recessed contacts are embedded in the door edge and frame, invisible from the surface, making magnet defeat attacks significantly more difficult. Specify recessed contacts for all high-security zone doors.

Use supervised contacts (with end-of-line resistors) that detect both open-circuit (door open) and short-circuit (wire cut) fault conditions. Supervised contacts report cable cuts to the panel as a fault rather than appearing normal — a critical feature for detecting deliberate sabotage before an intrusion attempt.

3.2 Window Contacts and Glass Break Detectors

Window contacts function identically to door contacts, detecting when a window sash opens. However, contacts alone do not detect glass breaking — an intruder can break out a window panel and enter without triggering the opening mechanism. Pair window contacts with glass break detectors for complete window coverage.

Glass break detectors use acoustic analysis to detect the specific sound signature of breaking glass — the initial impact and the subsequent acoustic ring of breaking glass. Quality glass break detectors (Bosch DS1101i, Honeywell FG-701) detect glass breakage within a 9-metre radius through 360-degree coverage from a ceiling-mount position, protecting multiple windows in the same room from a single device. Confirm the detector's range covers all glass in the protected area before finalising placement.

3.3 Passive Infrared Curtain Detectors

PIR curtain detectors project a thin, flat detection pattern (a "curtain" of infrared beams) rather than the wide volumetric pattern of standard PIR detectors. Curtain detectors are ideal for detecting passage through an opening: mounted above a window, the curtain detects any object that breaks the IR pattern as it passes through the window opening. Combined with a glass break detector (which triggers on glass breaking) and a curtain PIR (which triggers as the intruder enters through the broken window), the window protection is both complete and layered.

Chapter 4: Interior Detection

4.1 PIR Sensor Selection

Passive Infrared (PIR) detectors detect the thermal signature of moving warm bodies (humans, animals) against the cooler background of the room. PIR detectors are the most widely used interior motion detector and the most misapplied — wrong mounting height, wrong coverage pattern for the room geometry, or wrong sensitivity for the environmental conditions causes both missed detections and false alarms.

PIR mounting height: 2.0–2.4 metres is optimal for most commercial environments. Too low, and the detector may miss a crawling intruder. Too high, and warm air currents from HVAC systems may cause false alarms. The detection pattern at optimal mounting height covers a conical volume of typically 90–110 degrees horizontal and 15–20 metres maximum range.

For open-plan offices, position PIRs at the corners of the space to cover diagonal paths through the room. For corridors, use long-range (narrow-angle) PIR curtain detectors aimed along the corridor length. For irregularly shaped rooms, multiple PIRs with overlapping coverage ensure no blind spots.

4.2 Dual-Technology Sensors

Dual-technology (dual-tech) sensors combine two independent detection technologies — typically PIR and microwave — in a single housing. An alarm is only generated when both technologies detect movement simultaneously. This AND-logic dramatically reduces false alarms caused by single-technology triggers (HVAC air currents trigger PIR but not microwave; a cat triggers PIR but the mass is insufficient to trigger microwave; a passing vehicle's headlights through a window trigger PIR but not microwave).

Dual-tech sensors are strongly recommended for:

• Environments with active HVAC (warm air movement can trigger standard PIR)
• Areas with skylights or windows exposed to direct sunlight (solar radiation can trigger PIR)
• Facilities with small animals (SSAL frequently encounters this in older commercial buildings and industrial facilities in Dhaka and Chittagong)
• High-security zones where false alarm reduction is critical to maintaining response discipline

4.3 Microwave Barriers

Microwave barriers (also called microwave detectors or microwave beams) transmit a continuous microwave signal between a transmitter and a receiver. Any person or object that enters the detection zone disrupts the signal, triggering an alarm. Microwave barriers are used in large open spaces — warehouses, storage yards, parking structures — where a standard PIR's coverage range is insufficient.

Long-range microwave barriers achieve detection ranges of 50–150 metres, making them suitable for Bangladesh's large industrial facilities and warehouse complexes in Gazipur, Narayanganj, and BEPZA zones. Mount transmitter and receiver on opposing walls or structures with a clear line-of-sight between them. Multiple parallel beams (stacked 3–4 beams vertically) create a barrier that cannot be crawled under or climbed over.

Chapter 5: Alarm Panel Selection

5.1 Zone Capacity

Select an alarm panel with zone capacity 30–50% above your current design, to accommodate future expansion without panel replacement. For a current 40-zone design, specify a 64-zone or 128-zone panel. Panel replacement is expensive and disruptive; specifying adequate capacity upfront is a minimal additional cost.

Leading enterprise alarm panels for Bangladesh deployments:

• Bosch Solution 6000 / 16: Scalable from 16 to 144 zones. Widely deployed in banking and corporate environments. Strong integration with Bosch CCTV and Bosch Building Management.
• DSC PowerSeries Pro: North American standard panel, widely available in Bangladesh, 128 zones native with expansion. Strong feature set for commercial applications.
• Ajax Hub 2 Plus: IP and cellular native, wireless-first architecture, modern web-based management interface. Excellent for multi-site cloud management. Ajax has rapidly expanded its Bangladesh market presence.
• Honeywell Galaxy Dimension: European standard panel, strong for EN 50131 Grade 3 and Grade 4 compliance. Used in banking and government installations requiring certified compliance.

5.2 Power Backup

Every alarm panel must have adequate power backup to maintain system operation during mains power failure. Standard commercial specification: 24-hour standby backup with minimum 4-hour alarm operation capacity (sirens, GSM communicator operating simultaneously).

Calculate backup battery capacity: (Panel current draw × 24 hours) + (Siren current × 4 hours) ÷ (Battery voltage × 0.9 Usable capacity factor). Size the battery bank accordingly — sealed lead-acid (SLA) batteries are standard; lithium batteries are available at higher cost for smaller form factor.

Bangladesh's power supply reliability is improving but remains variable, particularly outside Dhaka and in areas served by smaller substations. In areas with frequent load shedding, extend backup duration to 72 hours standby.

Chapter 6: Communication and Monitoring

6.1 Single-Path vs. Dual-Path Communication

Single-path alarm communication — using only one communication method (telephone landline, or broadband, or GSM) — is a significant vulnerability. A sophisticated intruder targets the communication path before entering the building: cutting the landline, jamming the GSM signal, or disabling the broadband router. A single-path system that has had its communication path severed fails silently — the alarm triggers locally but no signal reaches the monitoring station.

Dual-path (dual-channel) communication uses two independent communication technologies simultaneously. Standard configurations:

• IP (broadband) + GSM (cellular): Primary path is IP over the building's broadband connection. If IP fails, the panel automatically switches to GSM mobile network communication. This is the minimum standard SSAL specifies for all commercial alarm installations.
• GSM + GSM (different network): Two SIM cards from different network operators (Grameenphone + Robi, for example) provide cellular redundancy if one network has an outage.
• IP + dedicated phone line: For facilities with existing landline infrastructure.

The dual-path system constantly monitors both communication channels and reports faults to the monitoring station if either path fails. A communication path failure alert — even without an intrusion alarm — warrants investigation, as it may indicate deliberate tampering before an intrusion attempt.

6.2 Central Monitoring Station (CMS)

A Central Monitoring Station (CMS) — also called an Alarm Receiving Centre (ARC) — is a 24/7 staffed operations centre that receives alarm signals and dispatches appropriate response. In Bangladesh, CMS services are provided by security companies and some alarm system manufacturers.

When evaluating CMS providers:

• Confirm 24/7 staffing with minimum 2 operators per shift
• Verify average alarm-to-response dispatch time (target: under 90 seconds from alarm signal receipt to response dispatch)
• Confirm the response protocol: who is called first (on-site security manager, building management, police)?
• Verify dual-path receiving capability (CMS must receive both your primary and secondary communication paths)
• Confirm the CMS holds a current operating licence and has adequate professional indemnity insurance

For banking sector installations, Bangladesh Bank's ICT Security Guideline v4.0 requires that alarm monitoring be connected to a certified monitoring centre with documented response procedures.

Chapter 7: Integration with CCTV and Access Control

7.1 Alarm-Triggered Camera Recording

When an intrusion zone activates, the VMS should immediately respond by: switching the associated cameras to continuous high-bitrate recording, popping up the camera view on the monitoring workstation screen, and saving an event bookmark in the footage timeline for easy retrieval during investigation.

This integration transforms the alarm response: the monitoring station operator sees a camera view of the alarm location within 2–3 seconds of alarm activation, enabling instant assessment of whether the alarm is a genuine intrusion or a false alarm. If genuine, the operator dispatches response while continuing to observe the intruder's movements through the camera.

Configure camera-zone mapping in the VMS integration: each alarm zone is mapped to one or more cameras covering that zone's detection area. Zone 007 (Ground Floor East Window) maps to Camera 12 (East Wall Interior) and Camera 14 (East Window Exterior). When Zone 007 activates, both cameras are immediately presented to the operator.

7.2 Access Control Lockdown

Integration between the intrusion alarm and the access control system enables automated lockdown: when a defined alarm condition activates (perimeter breach, panic alarm, or manual security console command), the access control system locks all non-emergency doors in the facility, preventing movement of an intruder between zones.

Configure lockdown trigger conditions carefully. A false alarm from a PIR detector triggering building-wide lockdown during business hours is highly disruptive. Define tiered lockdown levels: Level 1 (local zone lock — only doors adjacent to the alarmed zone lock), Level 2 (floor lockdown — all doors on the affected floor lock), Level 3 (full building lockdown — all doors except emergency exits lock). Escalate lockdown level based on confirmation of genuine intrusion.

Chapter 8: EN 50131 Compliance

8.1 Grade Selection

EN 50131 is the European standard for alarm systems (and the most internationally accepted standard for commercial intrusion detection). It defines 4 security grades based on the assumed threat level:

• Grade 1: Low risk. Intruders with little knowledge of alarm systems, using basic tools. Basic residential systems.
• Grade 2: Low-to-medium risk. Intruders with some knowledge of alarm systems, using a range of tools. Standard commercial applications.
• Grade 3: Medium-to-high risk. Intruders with significant knowledge of alarm systems, using portable electronic equipment. Banking, government, high-value commercial.
• Grade 4: High risk. Intruders with full knowledge of alarm systems and the ability to substitute components. Highest-security facilities, critical infrastructure.

For commercial Bangladesh deployments, Grade 2 is appropriate for standard office and retail environments. Grade 3 is required for banking, financial, and government facilities. Grade 3 requires certified panels (Honeywell Galaxy, Bosch Solution are Grade 3 certified), supervised wiring, dual-path communication, anti-masking detectors, and quarterly maintenance.

Chapter 9: Testing and Commissioning Protocol

9.1 Zone Testing

Test every zone individually before system handover:

1. Walk test each PIR zone: verify the PIR triggers when a person walks through its detection field at all corners of its specified coverage area
2. Open/close test each door and window contact: verify zone activation is recorded at the panel
3. Glass break test (using manufacturer-provided test instrument, never real glass breakage): verify detection
4. Tamper test each detector: remove detector from mount and verify tamper alarm at panel

9.2 Communication Test

With all zones tested, verify the communication path:

1. Arm the system and verify arm signal is received at the CMS
2. Trigger a test alarm and verify alarm signal and zone identification is received at CMS within 60 seconds
3. Disable the primary communication path (disconnect Ethernet/broadband) and verify the secondary GSM path takes over within 60 seconds
4. Verify CMS receives a communication fault alert when the primary path is disrupted

9.3 Integration Test

Test all integrations:

1. Trigger an alarm zone and verify VMS camera popup for the associated camera(s)
2. Trigger a panic button and verify lockdown response in access control system
3. Confirm all alarm events are time-stamped and correlate with VMS event log

Conclusion

An enterprise intrusion alarm system designed to the methodology in this guide — threat-assessed zone planning, correctly specified detectors for the environment, dual-path communication, CMS integration, CCTV and access control integration, and EN 50131 Grade 2 or Grade 3 compliance — provides the rapid detection and response capability that a modern Bangladesh enterprise requires.

The design failures we most commonly encounter in the Bangladesh market — single-path communication, incorrect PIR placement generating constant false alarms, inadequate zone count preventing location identification — are all addressable through engineering discipline at the design stage. Every one of the recommendations in this guide adds marginal cost at design time and eliminates exponentially larger costs in failed response, damaged assets, and system replacement.

SSAL designs and delivers enterprise intrusion alarm systems using Bosch, Ajax, Honeywell, and DSC platforms, with integration expertise across Milestone, Genetec, Hikvision, and Gallagher security platforms.

About SSAL

Smart Safety & Automations Ltd. (SSAL) is Bangladesh's leading enterprise security solutions provider, delivering intrusion alarm systems across banking, manufacturing, commercial real estate, and government sectors. Our certified alarm system engineers design, install, commission, and maintain systems to EN 50131 standards, with full integration to CCTV and access control infrastructure.

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