IEC 60331-3:2018

Overview

IEC 60331-3:2018 - Tests for electric cables under fire conditions - Circuit integrity - Part 3 describes a standardized test method for fire with mechanical shock applied to cables installed in a metal enclosure. The procedure is intended for low‑voltage cables with rated voltages up to and including 0,6/1,0 kV (600/1 000 V) and for test specimens with an overall diameter not greater than 20 mm. The fire exposure is to reach a temperature of at least 830 °C. The document specifies test apparatus, sample preparation, continuity checking, point of failure, test procedure and test report content for electric power and control cables.

Key topics and technical requirements

• Scope and applicability: Power and control cables up to 0.6/1.0 kV; scope extended to include metallic data/telecom and optical fibre cables (note: specific continuity and reporting details for those cable types are not provided in IEC 60331-3).
• Fire with shock: Combined exposure to a defined flame temperature (≥ 830 °C) and mechanical shock while cables are mounted inside a metal enclosure.
• Metal enclosure testing: Requirements for enclosure material, dimensions and mounting to simulate realistic installation conditions.
• Continuity checking & point of failure: Defined arrangements for monitoring circuit integrity during the test for power/control cables.
• Test specimen limits: Intended for cables ≤ 20 mm overall diameter; electrical arrangements and fusing specified for rated voltages up to the standard limit.
• Measurement control: Mandatory use of mass flow meters/controllers to accurately control fuel and air flow to the burner.
• Verification and reporting: Improved guidance on test environment verification and the content required in the test report.
• Voltage extension option: With manufacturer/purchaser agreement and suitable fuses, the procedure can be applied up to higher voltages (up to 1,8/3 (3,3) kV) - by agreement only.
• Limitations: Passing IEC 60331-3 does not imply compliance with IEC 60331-1 or -2; those tests must be carried out separately.

Practical applications

• Specifying and verifying circuit integrity for emergency power, fire detection, alarm, control and safety circuits installed inside metal enclosures.
• Type testing during product development and qualification of low‑voltage power and control cables for use in buildings, transport and industrial installations.
• Creating procurement and compliance requirements for cables where fire resistance under shock is critical.
• Supporting fire safety engineering, certification bodies and test laboratories in standardized fire‑with‑shock evaluations.

Who should use this standard

• Cable manufacturers and design engineers
• Independent test laboratories and certification bodies
• Fire safety engineers and consultants
• Procurement/specification teams in construction, rail, marine and industrial sectors
• Electrical contractors responsible for safety‑critical installations

Related standards

• IEC 60331-1, IEC 60331-2 (other circuit‑integrity test methods)
• IEC 60331 series parts (e.g., Parts 11, 21, 23, 25) - see IEC for scope and cross‑references

Keywords: IEC 60331-3:2018, circuit integrity, fire testing, cable fire test, metal enclosure, mechanical shock, 830 °C, low‑voltage cables, continuity checking, mass flow controller.