IEC 60947-3:2020

Overview

IEC 60947-3:2020 (Edition 4) is the international standard for low-voltage switchgear and controlgear - Part 3: switches, disconnectors, switch-disconnectors and fuse-combination units. It applies to equipment and dedicated accessories used in distribution and motor circuits with rated voltages up to 1 000 V AC or 1 500 V DC. This fourth edition cancels and replaces the third edition (2008) and its amendments, and introduces technical revisions that reflect modern switching needs for AC and DC systems.

Key topics and technical requirements

• Scope & classification: Definitions, equipment types, utilization categories and suitability for isolation for switches, disconnectors, switch-disconnectors and fuse-combination units.
• Rated and limiting values: Rated voltages, currents, frequency, duty and short-circuit characteristics for main, auxiliary and control circuits.
• Performance requirements and tests:
  • Making/breaking ability under no‑load, normal load and overload.
  • Short-circuit performance tests, operational endurance, temperature-rise and dielectric properties.
  • New tests added: critical load current tests for DC switches (9.3.9) and conditional short-circuit rating tests for equipment protected by circuit‑breakers (9.3.7.2).
  • EMC immunity and emission requirements.
• New or expanded annexes:
  • Annex A - new categories for high-efficiency motor switching.
  • Annex D - PV DC applications (photovoltaic DC switch requirements).
  • Annex E - requirements for connection to aluminium conductors.
  • Annex F - procedures for power losses measurement.
• Product information & marking: required documentation, marking, installation and maintenance instructions.

Practical applications

IEC 60947-3 is essential for:

• Designing and certifying low-voltage switchgear used in industrial distribution boards, motor control centers and machinery.
• Specifying and testing DC switches and PV DC isolators in renewable energy systems.
• Ensuring safe isolation, coordination with short-circuit protective devices, and reliable switching of modern high‑efficiency motors.
• Addressing specific installation needs such as aluminium conductor connections and verifying power losses for efficiency and thermal planning.

Who uses this standard

• Manufacturers of switches, disconnectors, switch‑disconnectors and fuse-combination units
• Test laboratories and certification bodies
• Electrical engineers, panel builders and system integrators
• Specifiers, procurement teams and compliance officers in industrial, commercial and renewable energy sectors

Related standards

• Other parts of the IEC 60947 series (general rules and related product parts) provide complementary requirements and should be consulted alongside IEC 60947-3 for complete low-voltage switchgear compliance.

Keywords: IEC 60947-3, low-voltage switchgear, switches and disconnectors, switch-disconnectors, fuse-combination units, DC switches, conditional short-circuit rating, aluminium conductors, power losses measurement, PV DC, motor circuits.