IEC Standard Voltages (Edition 4.0)

This technical specification defines the standard voltages for electrical power systems and equipment, serving as a foundational reference for global electrical engineering. Originally developed in the late 1960s, it has undergone revisions to accommodate evolving energy infrastructure and modernization requirements. The document establishes a systematic framework for nominal voltages across various frequency and phase configurations, ensuring compatibility and safety in international power distribution networks. It covers low voltage, medium voltage, and high voltage ranges applicable to alternating current and direct current systems. The content details specific voltage levels for three-phase and single-phase applications, facilitating seamless integration of electrical devices across different regions. Regular updates address technological advancements and changing operational needs, maintaining its relevance for utility providers, equipment manufacturers, and system designers. By harmonizing voltage standards, it supports interoperability and reduces technical barriers in cross-border electrical trade and infrastructure projects.