Overview
The IEC 60050-195:1998/AMD1:2001 amendment is a crucial update to the International Electrotechnical Vocabulary (IEV) Part 195, focusing on earthing and protection against electric shock. Published by the International Electrotechnical Commission (IEC), this amendment provides refined definitions, terminologies, and concepts that enhance clarity and consistency related to electrical safety, earthing systems, fault conditions, and protective measures against electric shock.
This standard is fundamental for electrical engineers, safety professionals, installation designers, and regulatory bodies who require precise vocabulary and understanding of earthing methods and electric shock protection mechanisms. It aligns international terminology and promotes safer electrical infrastructure design and operation worldwide.
Key Topics
Protective and Functional Earthing
- Protective Earthing (or protective grounding in US terminology): Earthing one or more points in a system or installation specifically to enhance electrical safety by preventing electric shock hazards.
- Functional Earthing: Earthing carried out for purposes other than electrical safety, such as operational or signaling reasons.
Electrical Fault Types
- Earth Fault (Ground Fault): The occurrence of an accidental conductive path between a live conductor and earth, which may result from insulation failure, structural contacts, or vegetation.
- Line-to-Earth Short-Circuit: A short-circuit involving a line conductor and earth in systems with solid or impedance-earthed neutrals.
- Line-to-Line Short-Circuit: Short-circuit between two or more line conductors, which may or may not be accompanied by a line-to-earth fault.
Neutral Earthing Systems
- Impedance Earthed Neutral System: Neutral grounded through an impedance designed to limit fault current, enhancing system protection.
- Resonant (Compensated) Earthing: Neutral connected to earth via inductance (arc-suppression coil) to compensate for line-to-earth capacitances, mitigating fault effects.
Electrical Safety Personnel Definitions
- Electrically Skilled Person: A person with suitable training and experience to recognize electrical risks and avoid hazards.
- Electrically Instructed Person: A person who, under supervision or adequate advice from skilled personnel, can identify electrical risks and maintain safety.
Protective Measures and Screens
- Electrically Protective Screen: A conductive barrier used to physically separate circuits or conductors from hazardous live parts to guard against electric shock.
- Protective Separation: Separation of electrical circuits using double or reinforced insulation and electrically protective screening to ensure safety under fault conditions.
- Fault Protection: Mechanisms and designs negating electric shock during single-fault situations, critical for safe electrical system operation.
Contact Current
- Defined as electric current passing through the human or animal body when in contact with accessible parts of electrical equipment or installations, a critical parameter for assessing shock risk.
Applications
The IEC 60050-195 amendment supports practical implementation in:
- Power Distribution Systems: Defining earthing neutral system types aids in planning fault detection and limiting fault currents to ensure system stability and personnel safety.
- Electrical Installation Design: Use of protective screens and separation concepts helps designers minimize shock hazards, complying with international safety standards.
- Safety Training: Clarified definitions for skilled and instructed persons provide a framework for competence requirements in electrical safety programs.
- Fault Analysis and Protection Coordination: Precise terminology regarding faults (earth fault, line-to-line short-circuit) enables consistent fault detection and protection relay settings.
- Regulatory Compliance and Documentation: Harmonized vocabularies help manufacturers, inspectors, and authorities refer to internationally recognized terms, ensuring clear communication.
Related Standards
- IEC 60364 series on Electrical Installations of Buildings, which incorporates earthing practices aligned with IEC 60050-195 terminologies.
- IEC 61000 series dealing with electromagnetic compatibility, where concepts like protective screening may overlap with electromagnetic shielding practices.
- IEC 60479 on effects of current on the human body, complementing the definitions related to contact current and electric shock protection.
- National electrical safety codes and regulations often reference IEC terminology for local standards harmonization.
Keywords: IEC 60050-195 amendment, earthing, electric shock protection, protective earthing, functional earthing, earth fault, impedance earthed neutral, resonant earthing, electrically skilled person, protective screen, contact current, fault protection, electrical safety standards, international electrotechnical vocabulary, IEC standards.
Open preview (PDF)Amendment 1 - International Electrotechnical Vocabulary (IEV) - Part 195: Earthing and protection against electric shock
