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Fire & Intruder Alarm Reference Guide

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How to date detectors:

  • Notifier/System Sensor: Locate the 4-digit code followed by a 'T'. Format: YYwwT (e.g., 2310T = 10th week of 2023).
  • Apollo: Format: YYMMDD (e.g., 230113 = 13th Jan 2023).
  • Gent: Format: WWYY (e.g., 5225 = 52nd week of 2025).

BS5839-1 Categories (Fire Detection and Fire Alarm Systems for Buildings):

  • M: Manual activation (e.g., Manual Call Points/MCPs only).
  • L1: Detection throughout all areas of the building, including any voids over 800mm high.
  • L2: Detection in high-risk areas as well as those defined in L3.
  • L3: Detection on escape routes and in rooms or areas that open onto those escape routes.
  • L4: Detection on escape routes only.
  • L5: Specific fire risks not covered by L1-L4.
  • P1: Detection throughout the whole building (MCPs not essential).
  • P2: Detection in specific, designated areas (MCPs not essential).

BS 5839-6 Grading (Domestic Fire Alarm Systems):

System Grades

  • Grade A: A system of detectors linked to a central control panel with battery backup, designed to commercial standards for the highest-risk properties.
  • Grade C: A system of interconnected detectors and alarms powered by the mains with a backup supply and a central controller.
  • Grade D1: A system of interlinked mains-powered alarms, each with its own tamper-proof, long-life backup battery.
  • Grade D2: A system of interlinked mains-powered alarms, each with a user-replaceable backup battery.
  • Grade F1: A system using alarms powered by a tamper-proof, long-life battery.
  • Grade F2: A system using alarms powered by user-replaceable batteries.

Categories of Protection (Coverage)

  • LD1: Provides maximum protection with detectors installed in all rooms and circulation areas where a fire could start.
  • LD2: Provides additional protection with detectors in all circulation spaces and high-risk rooms like kitchens and living rooms.
  • LD3: Provides minimum protection with detectors installed only in circulation areas that form part of an escape route.

Sound Levels:

  • 65dB: Standard minimum for most areas.
  • 60dB: Can be reduced in specific areas like a staircase or enclosed area up to 60m².
  • If background noise exceeds 60dB(A) for more than 30 seconds, the sounder must be 5dB(A) louder than that background noise.
  • Sleeping risk: 75dB @ bedhead.
  • 120dB: Maximum.

Intruder Alarm Grading (EN 50131):

  • Grade 1: Low risk (e.g., apartments), often not monitored.
  • Grade 2: Small to medium risk (e.g., retail stores), often monitored.
  • Grade 3: High risk properties (e.g., larger retail stores, warehouses, or high-value residential).
  • Grade 4: Banks, museums, or government buildings.

Ohm's Law & Power Formulas:

V = Voltage (Volts) | I = Current (Amps) | R = Resistance (Ohms) | P = Power (Watts)

Example: A 24V maglock drawing 500mA (0.5A) uses 12 Watts of power (24 × 0.5).

Common Default Codes (Master / Engineer):

Voltage Drop Formula:

Formula: (mV/A/m) × Current (A) × Length (m) ÷ 1000 = Drop in Volts

Common Intruder EOL Resistors (Alarm / Tamper):

Fire Cable Clip Spacing (BS 5839):

CCTV & Networking Essentials:

RJ45 Pinout (T-568B Standard) - Clip facing away:

  1. Orange/White
  2. Orange
  3. Green/White
  4. Blue
  5. Blue/White
  6. Green
  7. Brown/White
  8. Brown

Common Lens Angles (Approximate):

Access Control Reader Wiring (Standard Wiegand):

*Note: Paxton readers use a proprietary color code (Red/Black/Green/Orange/Mauve). Always check the manual for P-Series readers.

IP Ratings Guide (Ingress Protection):

First Digit (Solids): 4 = >1mm wire, 5 = Dust protected, 6 = Dust tight.
Second Digit (Liquids):

Rule of thumb: External devices should be minimum IP65.

Maglocks vs Door Strikes (Relays):

Engineer's Tax Relief (UK):

Did you know you can claim tax relief (HMRC P87 form) for:

Check the HMRC website for "Job Expenses" to claim back up to 4 years.