carrying out a wenner oil resistivity test via a det2-2 high powered earth test meter

Earthing Design

Churchill Specialist Contracting offer a complete earthing solution starting with a field based soil resistivity survey to assist with the initial design process, through to installation and commissioning for new build power stations, sub stations, switchyards and generators.

The starting point of the design phase is the Soil Resistivity Survey. The Wenner four terminal method is used to gather the accurate resistivity of the ground strata, typically from a depth of 60m through to 0.5m in a variety of increments. This information can then be used to provide a detailed soil model through specialist earthing software CEDEGS in preparation for a detailed earthing design.

CEDEGS provides us with a comprehensive report on the specific site requirements including a bespoke layout for your earthing system. From this a detailed ‘for construction’ issue drawing can be produced together with a competitive quotation for supply or supply, installation and commissioning of the earthing arrangement.

In summary, the minimum information required to design a suitable earthing system are:

  • Soil Resistivity
  • Expected Fault Current and Fault Current Characteristics
  • Fault Current Duration

However, for more complex installations further information will be required.

The main technical standards which need to be considered for specialist earthing include the following:

  • BS 7430:2011+A1:2015 Code of Practice for protective earthing of electrical installations
  • BSEN 50522:2010 Earthing of power installations exceeding 1KV
  • Electricity Association Technical Specification (EA TS) 41-24
  • ER S34: 1986 Earth potinetial rise in substations
  • IEEE 80 Guide for Safety in AC Substation Grounding
  • Electricty at Work Regulations 1989
  • Electricty Supply Regulations 1988
earthing design documents
earthing design documents