IEC 60255-27:2023 PDF

Overview

IEC 60255-27:2023 - Measuring relays and protection equipment - Part 27: Product safety requirements specifies product safety requirements for measuring relays and protection equipment with a rated AC voltage up to 1 000 V or a rated DC voltage up to 1 500 V. The standard focuses on minimizing risks of electric shock, fire, and injury to users and property. It addresses only product safety (not functional performance) and covers equipment mounting in cabinets, racks and panels as well as auxiliary devices (shunts, series resistors, transformers, auxiliary control panels, displays) that are tested together with the equipment.

Key topics and technical requirements

• Protection against electric shock: insulation, protective impedance, bonding, accessible parts and requirements for single-fault conditions.
• Earthing and protective bonding: general earthing rules, functional earthing, and protective conductor connections.
• Clearances and creepage distances: guidance for determining required distances and rated insulation/impulse voltages (see normative guidance).
• Mechanical safety: stability, moving parts, edges and corners, and mechanical security of terminations.
• Flammability and fire resistance: fire enclosures, flame barriers, material flammability requirements, minimizing ignition sources and assessing fire risk under normal and single-fault conditions.
• Design for safety: component integrity, climatic and environmental considerations, electrical connections, and special hazards (explosion, lasers, high-intensity light).
• Marking, documentation and packaging: identification, terminal and fuse marking, installation and maintenance instructions, warning labels and documentation durability.
• Testing and conformity: type and routine safety tests, climatic/mechanical tests, electrical safety tests, and verification procedures.
• Normative annexes: isolation class examples, rated impulse voltages, and guidance for clearances/creepage.

Practical applications

• Use IEC 60255-27 for product design and risk reduction when developing measuring relays and protection devices intended for use up to the specified voltage limits.
• Support type testing and product certification by manufacturers and third‑party labs to demonstrate compliance with product safety requirements.
• Guide installation and maintenance practices for utilities and panel builders to ensure safe mounting and wiring in racks and cabinets.
• Inform procurement and compliance teams when specifying safety-related requirements for protection equipment and associated auxiliary devices.

Who should use this standard

• Relay and protection equipment manufacturers and design engineers
• Test laboratories and conformity assessment bodies
• Utility and industrial specifiers, panel builders and system integrators
• Safety, compliance and regulatory professionals responsible for electrical equipment.

Related standards

• Other parts of the IEC 60255 series (measuring relays and protection equipment) and applicable IEC product-safety guidance for electrical equipment and components.