BS 7430 “Earthing”
A correctly designed and installed earthing system is essential for the safe function of equipment and the safety of people on site.
With this is mind Churchill’s experienced engineers carefully assess the site requirements and conditions when designing our earthing systems, to ensure the safe and reliable operation of our systems throughout their lifetime.
Once considered as a ‘black art’ earthing has become more scientific over recent years and the leading companies within our sector are now able to accurately model site specific conditions and predict electrical current dissipation under fault conditions and even the consequent voltages (step & touch) created over the site.
The starting point for any installation should be a site survey to determine the site characteristics and in particular the ‘soil resistivity’ of the below ground strata.
Where this data is unknown a soil resistivity survey should be carried out using a good quality earth tester and applying the “Wenner” four terminal method to gain an accurate indication of the ground conditions.
This data is then analysed and used with a combination of best practice engineering and a sound knowledge of all relevant industry standards to deliver a safe and reliable solution.
The technical standards which need to be considered include, but not limited too the following;
- BS 7430: 1999 – British Standard Code of Practice for “Earthing”
- IEEE 80 – Guide for Safety in AC Substation Grounding
- Electricity Association Technical Specification (EA TS) 41-24
- Electricty at Work Regulations 1989
- Electricty Supply Regulations 1988
Only the best quality components are used in our earthing systems, all of which are installed by our own highly trained engineers who operate throughout the UK.
The main factors to take into consideration when selecting the components are the current handling capabilities, for the example the expected fault current, and the life expectancy of the system, upon completion of an earthing system the whole installation is tested to ensure the design values have been met.
The minimum information required to design a suitable earthing system are:
- Expected Fault Current and Fault Current Characteristics
- Fault Current Duration
- Soil Resistivity (local to installation)
However for more complex installations further information will be required.
Our range of services range from design and installation of simple installations for generating plant, through medium sized installation for LV substation too large scale power station sites.
