In the United Kingdom, an earthing system identifies the electrical potential of the conductors relative to the conductive surface of the Earth. The world is a conductor rated at reference (zero) potential, referred to as earth in the UK. People are in direct contact with earth, so when something within a person’s reach becomes charged to a different voltage from earth a shock hazard occurs. The earthing process connects all parts which could become charged to the mass of earth to provide a path for fault currents which are a shock hazard. Earthing prevents a potential difference between earth and earthed parts, while allowing the flow of a fault current which will cause the operation of the protective system in place designed specifically to simply reduce the incidence of a shock hazard and provide protection in the case of lightning strike.
In the past, earthing was considered a black art, a practice with no scientific value, but regarded as necessary due to lore or tradition. Currently proper earthing processes are established through scientific methods to best predict electrical current dissipation under fault conditions and the consequent voltages possible. To design adequate earthing system specific information is gathered and evaluated: 1) expected fault current and its characteristics, 2) fault current duration, and 3) soil resistivity. The analysis of this information, best practice engineering, and utilization of industry standards create a dependable solution to reduce the hazard of electrical shock.
In the UK, the following technical standards are utilized to create earthing systems:
1. BS 7430: 1999 – British Standard Code of Practice for “Earthing”
2. IEEE 80 – Guide for Safety in AC Substation Grounding
3. Electricity Association Technical Specification (EA TS) 41-24
4. Electricity at Work Regulations 1989
5. Electricity Supply Regulations 1988
The services of a reputable lightning protection and earthing systems contractor should provide services including design, supply, installation, commissioning, test and inspection, plus maintenance of the systems after installation. Such specialists devoted to providing a comprehensive service for lightning protection and earthing systems in the UK can be found at Churchill Specialist Contracting Ltd. These specialists include engineers and installation teams with vast knowledge and experience and the sectors most comprehensively qualified and certificated operatives both on site and managerial level. All projects undertaken by CSC Ltd are completed in accordance with UK Codes of Practice and the new European standard BS EN 62305: 2006 “Protection Against Lightning and BS 7430 “Earthing.”
