BSI BS 7430:2026 Protective Earthing of Electrical Installations Code of Practice
 
This British Standard provides recommendations for earthing of electrical installations, including:
1. protective earthing of low voltage installations conforming to BS 7671:2018+A4:2026;
 
2. the interface between LV and HV substations conforming to BS EN IEC 61936‑1:2021+A11:2025 within buildings;
 
3. protective earthing arrangements for generators running in parallel with a distribution network operators (DNO) or a private HV/LV transformer supplying low voltage installations;
 
4. protective earthing and changeover switch arrangements for UPS and generators supplying low voltage installations; and
 
AC supplies derived from DC supplies, e.g. solar, batteries, wind.
 
NOTE 1 The earthing arrangement of a system or installation is typically provided for safety reasons and is not to be confused with protective equipotential bonding required by other British Standards (e.g. BS 7671:2018+A4:2026).
 
This British Standard applies to land-based installations in and around buildings.
 
NOTE 2 Whilst many of the principles of this British Standard can be applied equally to low voltage DC systems, this British Standard does not cover issues such as protection against galvanic corrosion that might be necessary for DC systems (see BS ISO 16364 for further guidance).
 
This British Standard does not include recommendations for maintenance of earthing systems and referenced conductors.
 
NOTE 3 Attention is drawn to Regulation 4 of the Electricity at Work Regulations 1989 [1]1) and Regulation 3 of the Electricity, Safety, Quality and Continuity Regulations (NI) 2012 [2]1) with regard to maintenance. See also BS 7671:2018+A4:2026 and the BS EN 62305 series for further guidance.
 
This British Standard does not apply to:
ships, aircraft, offshore or mining installations;
earthing of medical equipment (see the BS EN 60601 series);
problems encountered with solid state electronic components;
equipment sensitive to static electricity;
requirements for functional earthing;
railway traction equipment, rolling stock and signalling equipment;
protective earthing and protective equipotential bonding within hazardous areas where the BS EN 60079 series applies;
earthing of overhead lines between electrical installations; and
the internal protection of electrical equipment and apparatus.