Contents
Scope
Normative references
Terms and definitions
Earthing principles
HV/LV interface
Low voltage installations
Generators
Special installations
Earth electrode systems
Inspection and testing of the earthing system
1 Scope
This British Standard primarily provides recommendations and guidance on
meeting the requirements for the earthing of electrical installations, including:
a) protective earthing of low voltage installations to BS 7671:2008+A1;
b) the interface between LV and HV substations of 11 000/400 V to
BS EN IEC 61936-1:2011 within buildings; and
c) protective earthing and changeover switch arrangements for generators
supplying low voltage installations.
The earthing of a system or installation is generally provided for reasons of
safety.
This British Standard applies only to land-based installations in and around
buildings. It does not apply to:
1) ships, aircraft or offshore installations;
2) earthing of medical equipment [see BS EN 60601 (all parts)];
3) special problems encountered with solid state electronic components;
4) equipment sensitive to static electricity;
5) requirements for functional earthing;
6) earthing of overhead lines between electrical installations; or
7) the internal earthing of equipment.
BS 7430:2011+A1:2015 is the British Standard that provides a code of practice for the protective earthing of electrical installations. It offers comprehensive guidance on designing and implementing earthing systems to ensure safety and compliance with UK regulations.
Key Aspects of BS 7430:2011+A1:2015:
Scope and Application:
- The standard applies to land-based electrical installations within buildings, including low-voltage systems and the interface between low and high-voltage substations.
- It does not cover earthing requirements for ships, aircraft, offshore installations, medical equipment, or equipment sensitive to static electricity.
Earthing Systems:
- BS 7430 outlines various earthing systems, such as TN, TT, and IT systems, detailing their configurations and safety considerations.
- It emphasizes the importance of selecting appropriate earthing arrangements based on the specific characteristics of the installation.
Protective Earthing and Bonding:
- The standard provides guidelines for connecting exposed-conductive-parts of electrical equipment to the main earthing terminal.
- It highlights the necessity of protective equipotential bonding to reduce touch voltages and enhance safety.
Design and Installation:
- Recommendations are given for the selection of earthing conductors, materials, and sizes to ensure effective fault protection.
- The standard advises on the installation of earth electrodes, considering factors like soil resistivity and environmental conditions.
Testing and Maintenance:
- BS 7430 outlines procedures for testing earthing systems to verify their effectiveness.
- It underscores the importance of regular maintenance to ensure ongoing safety and compliance.
For detailed information and specific guidelines, refer to the full text of BS 7430:2011+A1:2015. This standard is essential for professionals involved in the design, installation, and maintenance of electrical installations in the UK.
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