Overview
IEC 61140:2016 - Protection against electric shock establishes fundamental principles and common requirements for protecting persons and livestock from electric shock. As a fourth-edition basic safety publication (IEC Guide 104), it applies to electrical installations, systems and equipment for voltages and currents of any magnitude, for frequencies up to 1 000 Hz. The standard defines how protective provisions and measures should be coordinated across equipment and installations to achieve basic, fault and additional protection.
Key topics and technical requirements
IEC 61140 organizes technical requirements around protective provisions and measures. Major topics include:
- Fundamental rule of protection for normal and single-fault conditions, and special additional protection.
- Basic and fault protection elements such as:
- Basic and supplementary insulation, reinforced insulation
- Protective barriers, enclosures and obstacles
- Protective-equipotential-bonding and protective screening
- Automatic disconnection of supply
- Enhanced and additional protective provisions:
- Double/reinforced insulation, protective separation, limited current sources, protective impedance devices
- Additional protection by residual current devices (RCD) - IΔn ≤ 30 mA (for additional protection)
- Supplementary protective equipotential bonding
- Protective measures such as electrical separation, SELV and PELV systems, limitation of steady‑state touch current and charge energy, and non‑conducting environments.
- Co‑ordination of equipment classes (Class 0, I, II, III) with installation protective provisions.
- Touch currents, protective conductor currents and leakage currents: definitions, limits and coordination requirements for safety.
- Service, isolation and maintenance conditions, including devices intended to be operated or replaced by ordinary, skilled or instructed persons.
- Annexes and informative guidance: surveys of protective measures, values and definitions.
Applications and who uses this standard
IEC 61140 is used by a wide range of professionals and organizations concerned with electrical safety:
- Electrical designers and system integrators - to select and coordinate protective measures.
- Equipment manufacturers - for product classification (Class I/II/III) and compliance with insulation, bonding and touch-current requirements.
- Installers and contractors - for safe installation practices, earthing and bonding, and choosing RCD protection where needed.
- Safety engineers, auditors and regulators - for risk assessment, conformity verification and national implementation.
- Test laboratories - to evaluate touch currents, protective conductor currents and insulation measures.
Practical applications include building electrical installations, industrial power systems, medical device interfaces, control panels, and high-voltage installations where consistent protection strategies are required.
Related standards
IEC 61140 is a basic safety publication and is intended to be used alongside more specific IEC/ISO standards for equipment and installations (for example standards covering particular product families, earthing systems, or RCD testing). Always check national regulations and the latest IEC publications for harmonized requirements.
