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🔊 Public Address & Voice Alarm (PAVA) Systems

Overview

Public Address & Voice Alarm (PAVA) systems are specialised sound systems designed to deliver life safety messages during an emergency, in addition to providing public address and background audio functions during normal operation.

In the UK, PAVA systems are treated as safety services under the Electricity at Work Regulations 1989 (EAWR) and must be installed, operated, and maintained in accordance with electrical safety legislation and relevant British/European standards.

Regulatory Framework

⚖Electricity at Work Regulations 1989 (EAWR)

  • All electrical systems must be constructed and maintained so as to prevent danger.

  • Applies to PAVA systems because:

    • 100 V line speaker circuits exceed the 50 V AC extra-low voltage (ELV) threshold → classed as Low Voltage (LV, Band II).
    • Amplifier and PSU components often run at 300-600 V internally, requiring competent persons for installation and servicing.

  • Implication: Only those with appropriate electrical training and competence should install or modify PAVA cabling and equipment.

Standards and Compliance

🏗Design & Installation

  • BS 5839-8 - Code of practice for voice alarm systems.

  • BS EN 54-16 - Voice alarm control and indicating equipment.

  • BS EN 54-24 - Loudspeakers for voice alarm.

  • BS EN 54-4 - Power supply equipment.

  • BS 7671 (IET Wiring Regs) - Electrical safety, including:

    • Section 560: Safety services.
    • Section 534: Surge protection (with reference to BS EN 62305 lightning protection).

Cabling & Fire Resistance

  • BS 8434-1 & -2 - Fire test methods for cable survival.
  • BS 8519 - Selection/installation of fire-resistant cable systems for life safety and firefighting systems.
  • Enhanced fire-resisting cables generally required in stadiums, hospitals, tunnels, transport hubs.

🔊 Operational Requirements

  • PAVA must always have priority over background music, advertising, or commentary.
  • Messages must be intelligible (tested via STIPA/STI).
  • Systems must provide 24 h standby + 30 min full alarm operation on battery supply.

Electrical Safety Considerations

🔹 100 V Line Circuits

  • Operate at 70-100 V RMS AC audio signal → Band II (LV) under BS 7671.
  • Requires electrical competence for installation and testing (continuity, insulation resistance, polarity).
  • Must be segregated from Band I circuits (fire alarm loops, ELV data/control).

🔹 High-Voltage Internal Components

  • Amplifiers, PSU units, and changeover modules can operate with 300-600 V DC rails internally.
  • Only competent persons should access live enclosures.
  • Risk assessments under EAWR required before live testing/maintenance.

🔹 Surge & Lightning Protection

  • Long 100 V lines between buildings or across stadium/transport sites are susceptible to induced surges.
  • Must be protected via SPDs as per BS 7671:534 and BS EN 62305-4.
  • Fibre-optic distribution (immune to surges) is increasingly preferred for backbone links.

Health & Safety Competence

  • Because 100 V PAVA lines are Low Voltage, staff without formal electrical training (e.g. general fire/security engineers) should not install or modify them.

  • Competency requirements:

    • Electricians or those with equivalent LV training: Installation & testing.
    • PAVA specialists/commissioning engineers: Programming, zoning, intelligibility testing.
    • Joint training recommended for multidisciplinary teams.
  • BS 9999 / BS 9991 - Fire safety design and evacuation strategy (defines when VA is required).
  • BS 8644-1 - Digital records (golden thread) → commissioning/test results must be recorded.
  • EAWR 1989 - Legal obligation to ensure safe electrical systems at work.

Electrical Safety & Competence (EAWR Context)

PAVA systems, particularly those built on 100 V line distribution, operate with internal voltages of up to 600 V. Both the line outputs and the amplifier internals far exceed the 50 V AC “safe touch” threshold defined in UK legislation.

The EAWR Position

The Electricity at Work Regulations 1989 (EAWR) require that:

  • No person shall be engaged in work on or near electrical equipment unless they have the knowledge, training, and experience to do so safely (Regulation 16).
  • The employer must ensure safe systems of work are in place, including isolation, lock-off, test-before-touch, and risk assessment.

Competence Boundaries in Practice

  • Fire Alarm Engineers

    • Competence is usually centred on ELV/SELV systems (≤ 50 V AC / 120 V DC).

    • Many are not electrically qualified to work on LV mains supplies (e.g., 230 V panel feeds) or 100 V line terminations.

    • In strict compliance terms, their role is limited to:

      • Programming, configuration, and software-based commissioning.
      • Functional testing once the electrical installation has been safely completed and energised by a competent person.
      • Visual inspection of wiring for correct segregation and containment.

  • Electrically Competent Persons (Electricians / Electronics Engineers)

    • Required for:

      • Terminating and testing 100 V line speaker circuits.
      • Installing and energising panel mains supplies.
      • Working inside amplifiers with HV rails (400-600 V).
      • Carrying out repairs, replacements, and component-level fault-finding.

Practical Implications

  • Fire alarm companies often rely on electricians to install and terminate PAVA cabling (both mains and 100 V lines).
  • Fire alarm engineers then commission the system in software and functionally test it, but do not carry out electrical works.
  • This split of responsibility ensures compliance with EAWR while still allowing specialist fire engineers to handle system logic, cause-and-effect, and voice message testing.

Key Point: Under EAWR, fire alarm engineers are not automatically qualified to work on 100 V line circuits or panel mains feeds. Their role is restricted to the non-electrical aspects of commissioning and maintenance, with all electrical terminations and HV work carried out by appropriately trained and authorised electrical personnel.

Summary

PAVA systems in the UK are not just audio equipment - they are life safety electrical installations.

  • 100 V line circuits = Low Voltage (Band II) under BS 7671 → must be treated as such for segregation and safety.
  • Internal components may operate at up to 600 V, meaning EAWR competence rules apply.
  • Compliance requires integration of fire safety standards (BS 5839-8, EN 54) with electrical regulations (BS 7671, BS 8434, BS 8519, EAWR 1989).
  • Only competent, trained personnel should design, install, or maintain PAVA systems.