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2025-09-19 20:09:01 R. Bishop: -/-| /dev/null .. fire alarms/regulations/bs7273-4.md | |
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| + | # BS 7273-4: Actuation of Release Mechanisms for Doors |
| + | |
| + | ## Overview |
| + | |
| + | **BS 7273-4:2015 + A2:2023** is the British Standard that governs how **electrically locked or held-open doors on escape routes** must be released in the event of fire or system fault. |
| + | |
| + | The standard ensures that escape doors controlled by electricity always release **reliably, quickly, and fail-safe**, maintaining the principle of free egress under the **Regulatory Reform (Fire Safety) Order 2005** and related legislation. |
| + | |
| + | --- |
| + | |
| + | ## Scope |
| + | |
| + | BS 7273-4 applies to: |
| + | |
| + | * **Electrically locked doors** (maglocks, solenoid bolts, shear locks, etc.) |
| + | * **Electrically held-open doors** (e.g. electromagnetic door retainers) |
| + | * **Doors on escape routes or final exits** where release must be guaranteed |
| + | |
| + | It does **not** apply to purely mechanical hardware (e.g. un-locked panic bars). |
| + | |
| + | --- |
| + | |
| + | ## Categories of Actuation |
| + | |
| + | BS 7273-4 defines **three categories of system integrity**, depending on the criticality of the door: |
| + | |
| + | | Category | Release Conditions | Typical Applications | |
| + | | -------------------- | ------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------- | |
| + | | **A (Highest)** | Must release on fire alarm **and** on virtually any fault (open circuit, short, loss of power, isolation of fire panel). | Final exits, stair cores, high-risk areas | |
| + | | **B (Intermediate)** | Must release on fire alarm plus certain critical faults. | Escape doors on main circulation routes | |
| + | | **C (Basic)** | Must release only on fire alarm. | Lower-risk areas with alternative exits | |
| + | |
| + | --- |
| + | |
| + | ## Manual Release Devices |
| + | |
| + | Every electrically locked escape door must also have a **local manual means of release**, even if the fire alarm system is interfaced. |
| + | |
| + | ### Acceptable Devices |
| + | |
| + | * **BS EN 54-11 Type B manual call point (MCP)** |
| + | |
| + | * Resettable or frangible “break glass” type |
| + | * Provides direct contacts to drop lock power |
| + | * **Emergency Door Release (EDR) unit to BS 7273-4 requirements** |
| + | |
| + | * Clearly marked green unit labelled *Emergency Door Release* |
| + | * Provides sustained fail-safe release |
| + | |
| + | ### Placement |
| + | |
| + | * Adjacent to the door on the escape side |
| + | * Height approx. 1.4 m, visible and unobstructed |
| + | * Illuminated where lighting is poor |
| + | |
| + | ### Non-Compliant Devices |
| + | |
| + | * **Timed auto-reset units** (that re-lock after a delay) |
| + | * **Push-and-hold-only buttons** (release only while held in) |
| + | Both fail because the standard requires **sustained release until reset**. |
| + | |
| + | --- |
| + | |
| + | ## Performance & Timings |
| + | |
| + | * Door must release within **3 seconds** of actuation (fire, fault, or manual). |
| + | * Release devices must be robust and suitable for repeated operation. |
| + | * Locks must **fail safe** (loss of power releases the door). |
| + | |
| + | --- |
| + | |
| + | ## Integration with Fire Alarm Systems |
| + | |
| + | * Release mechanisms must be controlled by the **fire detection and alarm system (FDAS)**. |
| + | * Fire alarm interface alone is **not sufficient** — local MCP/EDR still required. |
| + | * Categories A and B require **fault monitoring** of circuits. |
| + | |
| + | --- |
| + | |
| + | ## Panic Bars and Exit Hardware |
| + | |
| + | **BS EN 1125** (panic bars) and **BS EN 179** (emergency push pads/levers) require that doors open by a **single mechanical action**, regardless of electrical systems. |
| + | |
| + | ### Non-Compliant |
| + | |
| + | * Maglocks fitted to doors with panic bars or pads: |
| + | |
| + | * The panic hardware cannot mechanically override the lock. |
| + | * Escape depends on electrical release, breaching EN 1125/179. |
| + | |
| + | ### Compliant |
| + | |
| + | * **Electrified panic hardware** tested and CE-marked to EN 1125/179: |
| + | |
| + | * Push bar always mechanically releases the door. |
| + | * Electronic control is supplementary (e.g. latch retraction for access). |
| + | * **Mechanical escape doors kept separate from access-controlled doors**. |
| + | |
| + | --- |
| + | |
| + | ## Maintenance |
| + | |
| + | * All doors, release devices, and interfaces must be tested during **routine FDAS maintenance** (BS 5839-1). |
| + | * MCP/EDR units should be checked regularly for correct operation. |
| + | * Documentation must record: |
| + | |
| + | * Category of actuation per door |
| + | * Wiring and interfaces |
| + | * Commissioning/test results |
| + | |
| + | --- |
| + | |
| + | ## Key Points |
| + | |
| + | * BS 7273-4 ensures electrically controlled escape doors always release fail-safe. |
| + | * Manual local release (green MCP/EDR) is always required. |
| + | * Auto-reset or push-and-hold devices are non-compliant. |
| + | * Panic bars must provide a **mechanical override** — maglocks across them are not acceptable. |
| + | * Compliance requires correct design, installation, testing, and maintenance. |