IEC 60331-4:2024

Overview

IEC 60331-4:2024 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies the test method for evaluating the circuit integrity of electric power cables under fire and shock conditions. This part of the IEC 60331 series is focused on cables with rated voltages higher than 1 kV up to and including 30 kV. The standard outlines detailed procedures for subjecting cables to fire at temperatures of at least 830 °C, combined with mechanical shock, in order to assess their ability to maintain circuit integrity during such extreme events.

Maintaining circuit integrity in high voltage cables during fire is critical in ensuring the continued operation of essential safety systems and minimizing risk in critical infrastructure. IEC 60331-4:2024 provides a robust framework and reproducible methodology to verify cable performance under challenging fire and mechanical shock conditions.

Key Topics

• Scope and Applicability

  • Applies to power cables rated higher than 0.6/1.0 kV up to 18/30 kV.
  • Test method is restricted to cables with conductor sizes up to 120 mm². Successful testing at 120 mm² qualifies larger sizes of the same construction.
  • Relevant for single-core and preassembled three-core cables.

• Test Apparatus and Procedure

  • Specifies use of a steel test ladder, ribbon-type propane gas burner, shock-producing device, and voltage supply arrangement.
  • Details on specimen preparation, cable mounting, sample conditioning, and environmental requirements.
  • Includes guidance for testing with optional water spray or water jet protocols for enhanced realism.

• Performance Requirements

  • Recommends flame application times (typically 30, 60, 90, or 120 minutes) and flame temperature (minimum 830 °C, with an option for 1,000 °C for special applications).
  • Outlines acceptance criteria: continuity of circuit without voltage breakdown and verification of conductor integrity after test completion.

• Documentation and Marking

  • Specifies detailed requirements for test reporting, including test setup, conditions, and observations.
  • Allows optional marking on cables to demonstrate compliance with IEC 60331-4 and duration of flame application, enhancing traceability in procurement and installations.

Applications

• Critical Infrastructure

  • Suitable for testing and qualifying cables used in power stations, substations, tunnels, hospitals, airports, and other facilities where maintaining power during fire is essential.
  • Supports regulatory compliance for building safety and emergency systems.

• Product Development and Certification

  • Provides manufacturers and testing laboratories with a harmonized international test method for circuit integrity under fire conditions.
  • Used as a benchmark for qualifying new cable designs and ensuring consistency across product ranges.

• Standardization and Regulatory Reference

  • Acts as a group safety publication for use by IEC technical committees in the development and harmonization of related product standards.
  • Offers guidance in preparation of standards for similar products, following IEC Guide 104 and ISO/IEC Guide 51 principles.

Related Standards

• IEC 60331-1: Tests for electric cables under fire conditions - Circuit integrity (for cables up to 0.6/1.0 kV, overall diameter exceeding 20 mm)
• IEC 60331-2: For cables up to 0.6/1.0 kV with a diameter not exceeding 20 mm
• IEC 60331-3: For cables up to 0.6/1.0 kV tested in a metal enclosure
• IEC 60331-11, -21, -23, -25: Addressing apparatus and procedures for different cable types (power, data, optical fiber) at lower voltages
• IEC 60584-1: Thermocouples - Reference for temperature measurement apparatus
• IEC Guide 104: Preparation of safety publications and use as group safety publications

IEC 60331-4:2024 provides vital assurance for the fire safety performance of high voltage cables, supporting risk mitigation and regulatory compliance in power and safety-critical environments. Following this standard helps ensure continued service of essential systems during fire emergencies.