Core Functions of Interconnection Wires

Technical Definition:Interconnection wires are specialized cables for electrical linking between multiple smoke detectors,primarily transmitting three signals:

  1. Alarm signal (12-24V DC pulse)
  2. Status feedback (NO/NC contacts)
  3. Power supply (shared power bus)

1 Interconnection Working Principle

When any detector triggers,the interconnected circuit will:

  • Activate sounders/lights on all detectors (sync delay ≤3s)
  • Send address codes to fire control panel (addressable systems)
  • Maintain backup power switching (meets NFPA72 90-min requirement)

Smoke Detector Wire Types and Technical Standards

Wire Type Technical Parameters Compliance Standard Max Transmission Distance
RVVP Shielded Cable 3×1.0mm² (18AWG) GB/T 5023.3 150m
FPLP Flame-Retardant 2×1.5mm² (16AWG) UL 1424 300m
Twisted Pair 22AWG,120Ω impedance EN 54-25 500m

Important Notice:When interconnecting different brands,protocol compatibility must be verified (e.g. Edwards EST3 systems only accept proprietary FPLR cables)

Smoke Detector Wiring Methods and Installation Standards

1 Typical Wiring Topologies

  • Series connection:Traditional dry contacts (max 10 devices)
  • T-tap branches:Complies with NFPA 72 Class B circuits
  • Ring loop:Commercial redundancy design (auto-fault alert)

2 Mandatory Installation Requirements

  1. Separation from power lines:≥300mm (parallel)/100mm (cross)
  2. Conduit fill ratio ≤40% (metal conduits require grounding)
  3. Termination with 10kΩ resistor (addressable systems)

Frequently Asked Questions

Q1:Can Ethernet cables replace dedicated interconnection wires?

A:Only shielded Cat5e+ cables meeting:

  • Conductor size ≥0.2mm² (24AWG)
  • UL 2196 vertical flame test
  • Transmission distance ≤80m (signal attenuation compensated)

Q2:How to detect wire aging?

A:Professional methods include:

  1. Insulation resistance test (≥100MΩ at 500V DC)
  2. Loop impedance test (≤50Ω including all nodes)
  3. Signal integrity test (oscilloscope waveform analysis)

Maintenance and Testing Standards

Maintenance Item Test Method Pass Criteria Frequency
Wire Continuity Multimeter resistance ≤1Ω/100m Quarterly
Insulation Performance 500V megger ≥100MΩ Annual
Signal Strength Oscilloscope ≥2V peak-to-peak Annual