IEC 63522-33:2025

Overview

IEC 63522-33:2025 – Electrical relays – Tests and measurements – Part 33: Continuity of protective earthing connection is an international standard developed by the International Electrotechnical Commission (IEC). This standard specifies test methods to evaluate the ability of all types of electrical relays to maintain a reliable and low-resistance connection between an earthing terminal and parts required to be connected during transportation, storage, and all aspects of operational use.

Ensuring the continuity of the protective earthing connection is a vital safety aspect for electrical relays, particularly those intended for connection to mains circuits. Proper earthing helps prevent electric shock, protects against equipment failure, and ensures compliance with global safety requirements.

Key Topics

• Scope of Application
  IEC 63522-33 applies to various types of electrical relays, including electromechanical relays, reed relays, time relays, solid state relays, and combinations of these technologies. The standard is relevant for all relays equipped with an earthing terminal intended for use in systems connected to the mains.

• Test Methods
  The document outlines methods to verify that the connection between the earthing terminal and required parts maintains a low resistance:

  • Application of a defined test current (at least 1.5 times the rated current, not less than 25A) at a controlled voltage (maximum 12V AC or DC).
  • Measurement of voltage drop to determine the resistance of the earthing connection.
  • Alternative test procedures may be used if they yield consistent and repeatable results.

• Test Conditions
  The standard specifies critical parameters to be set before testing, including:

  • Test current and voltage
  • Identification of all parts that require earthing connection
  • Resistance limit (commonly not exceeding 0.1 Ω)
  • Any deviations from the main procedure

• Reporting and Evaluation
  Detailed guidance is provided for evaluating results and reporting:

  • Confirmation that the measured resistance does not exceed specified limits
  • Documentation of test conditions, devices under test, probe application points, and test equipment
  • Recommendations for standalone or integrated test reporting

Applications

IEC 63522-33:2025 is essential for:

• Manufacturers
  Ensuring consistent manufacturing quality and safety compliance of relays intended for international markets. Verification of earthing integrity risk-reduces product liability and field issues.

• Testing Laboratories
  Providing a uniform method for safety and compliance testing of electrical relays before market entry or as part of certification schemes.

• Product Designers and Engineers
  Assisting in the proper design and construction of relay products with reliable earthing connections, facilitating compliance from the outset.

• Regulatory and Certification Bodies
  Offering a clear standard against which products can be assessed for conformity to earthing continuity requirements.

Related Standards

• IEC 63522-0
  Electrical relays – Tests and measurements – Part 0: Testing – General and guidance (foundational document for series)

• IEC 60050-195
  International Electrotechnical Vocabulary (IEV) – Part 195: Earthing and protection against electric shock (for terminology)

Users of IEC 63522-33:2025 should consult these related standards for comprehensive testing, terminology, and guidance on electrical relays and earthing requirements.

Keywords: IEC 63522-33, electrical relays, earthing continuity, protective earthing connection, relay testing, low resistance, relay standards, relay safety, international electrotechnical standards, electrical safety compliance.