• Home
        • Generation
        • Aurora works across a wide range of traditional power generation systems, from small CHP units up to large industrial power generation facilities. We have extensive experience in considering synchronous generators fault contribution into the network, as well as considering issues such as dynamic response and transient stability of synchronous generators.

        • Renewables & Energy Storage
        • Aurora provides a range of services to the Renewables and Battery Energy Storage Systems industries, and can provide advice on analysis on greenfield developments or integration into existing brownfield industrial facilities. We specialise in providing grid simulation and G99 compliance studies to support renewable connections to the UK network, and other European networks.

        • Transmission & Distribution
        • Aurora has extensive experience in the transmission and distribution sector, dealing with private 11kV and 33kV networks, iDNOs and DNOs and National Grid, for a variety of different design and analysis applications.

        • Oil, Gas and Petrochemical
        • Aurora has extensive experience in the Oil & Gas industry, and has undertaken a wide range of design activities, concept studies and simulation studies to support many large international EPC companies and service companies.

        • Industrial
        • Aurora works in light and heavy industry providing a range of services to help plant owners analyse and understand their networks, identify weak spots, providing guidance on system loadings, fault levels, earthing, protection coordination and arc flash.

        • Data Centres
        • Aurora has worked on a number of large data centres, providing a range of services to support existing specialist companies in this area, such as system analysis for fault levels, harmonic analysis, protection coordination and arc flash analysis.

        • Building Services
        • Aurora works in Building Services industry to support multiple M&E contractors in development of the HV aspects of their design, or integration of renewable technologies like roof top solar.  Services include system analysis for fault levels, harmonic analysis, protection coordination and arc flash analysis.

        • Water
        • Aurora has extensive experience in the water industry and has worked fs, identify weak spots, providing guidance on system loadings, fault levels, protection coordination, motor starting earthing and arc flash. We also have extensive experience in helping water companies integrating renewalbe power and battery storge technologies into their sites.

        • Power System Analysis
        • Load flow, fault analysis, P28/2 voltage disturbance including flicker and transformer inrush, G5.5 Harmonics, G99 Grid studies, protection coordination, arc flash, dynamic and transient studies and electromagnetic transients.

        • Power System Design
        • Concept selection, contingency analysis, switchgear and transformer specification, SLD preparation, cable sizing, UPS sizing, substation layouts, protection scheme design, wiring modifications for EPC and M&E companies.

        • Power System Earthing
        • Earth potential rise (EPR) calculations and touch and step voltage calculations with either CDEGS or XGSLab, earthing layouts, soil resistivity testing, fall of potential tests, earthing inspections and resistance testing.

        • Power System Consultancy
        • Concept development and decarbonisation strategies, preparations of G99 and National Grid connection applications, review of ICP and vendor proposals, due diligence checks and client representative and failure investigations.

  • Case Studies
        • Team
        • As a consultancy our people are our greatest assets. Please follow the link above to meet the Aurora Team and find out more about us.

        • Careers
        • Are you interested in power system studies and analysis? Would you like to work for Aurora? If so click the above link to see our current vacancies.

  • News
  • Contact

Power System Earthing

Key Features

  • HV earthing studies in accordance with BS EN 50522, ENA 41-24, ENA S34 and IEEE-80
  • Industry standard CDEGS package (RESAP, FCDIST, MALT, MALZ, TRALIN, SPLITS)
  • New XGSLab package (XGS_SA and NETS)
  • Optional use of ETAP ground grid modelling software
  • Calculation of Earth Potential Rise (EPR)
  • Determination of site classification as Cold/Hot
  • 3D contour plots of touch and step voltages
  • Calculation of safe touch and step voltages
  • Optimisation of earth rod and conductor layout
  • Development of exclusion zones in sensitive areas
  • Protection of livestock
  • Guidance on static shocks
  • Mitigation strategies for transferred potential
  • Interfaces to lightning protection systems
  • Interfaces to cathodic protection systems.

Earthing and Grounding Capabilities

Power system HV earthing design and earthing studies are one of the most deceptively complicated areas in electrical engineering, and are frequently misunderstood, or poorly designed. A correctly functioning earthing system is essential for safe operation of the system and protecting personnel and livestock against electric shock. At Aurora we have experience of working to BS EN 50522, ENA 41-24, ENA S34 and IEEE-80.

Aurora is also one of the few companies in the UK to possess the industry standard CDEGS grounding software package and have the knowledge to use it, with our Director being a Certified Level 1 user (one of only 21 engineers within the UK). This powerful package allows us to carry out sophisticated grounding design for larger sites and meet the stringent requirements of utility companies. As well as using CDEGS, we have recently invested in XGSLab, which brings a new and exciting dimension to earthing studies, through a much more flexible and advanced user interface for carrying out earthing studies.

Earth Potential Rise and Touch and Step Voltage Calculations 

An Earth Potential Rise (EPR) Calculation, (also known as Rise of Earth Potential ROEP) and the associated touch and step voltage calculations are of key importance to ensure site safety of an earthing grid. We have frequently encountered engineers who believe that if they have a ‘good’ earth impedance of a few ohms, then their system is safe – which couldn’t be further from the truth. Power system earthing is a complex, iterative design process which needs to determine the soil resistivity, DNO fault levels and then the associated EPR and touch and step voltages. If these values are too high then there is a very real safety risk to personnel both in the substation and nearby, as well as any nearby livestock.

Aurora uses the industry standard CDEGS or XGSLab package for undertaking earthing designs, which allows us to build complex layer soil models with special backfills, calculate complex fault current distribution and build detailed models of the earthing system and nearby underground features (such as pipes, other structures, etc.) to produce 3D graphical representations of the touch and step voltages.

Earthing Design

Aurora can undertake a complete earthing design for any power system, with the aim of ensuring that all items of equipment are correctly earthed with the right sized conductor and optimise the earth nest layout to suit the site conditions and reduce costs.  Aurora has detailed knowledge of all aspects of power system earthing design and can provide guidance on optimising earthing layouts to help reduce costs and ensure that all equipment, personnel and livestock is fully protected.

Earthing Surveys

Aurora can undertake a complete earthing survey for any power system, with the aim of checking and investigating to ensure that the earthing system is adequately sized and rated for the required duty, and that all conductors, joints and rods are performing as required. The surveys are usually carried out through a mixture of visual identification, micro-ohmmeter testing of joints and conductors and use of an earth clamp meter to test individual rods. In addition sometimes it is also beneficial to carry out soil resistivity surveys and/or fall of potential tests.

Soil Resistivity Surveys

Carrying out a soil resistivity survey, is the first step to undertaking an earthing design. At Aurora we have the industry leading Megger Det 2/2 earth tester which we use for all soil resistivity surveys. Surveys are typically carried using the Wenner 4-pin method at 2 to 3 different locations, using spacings in accordance with BS EN 50522, to give a complete indication of the soil configuration, which can then be entered into CDEGS or XGSLab. Depending on the site location, Aurora will either carry out this test ourselves, or subcontract it to a local company, to help keep the overall costs down.

Fall Of Potential Tests

Once an earthing system has been installed, it is usually necessary to validate that the overall earth grid impedance matches the figure calculated in the CDEGS or XGSLab model. There are various test methods available for carrying out this test, but the preferred method for most sites is known as the Fall Of Potential method. At Aurora we use the Megger Det 2/2 to obtain a series of readings at a suitable distance from the site, until a stable value is confirmed for the site overall earth grid impedance. As with the soil resistivity survey, depending on the site location, Aurora will either carry out this test ourselves, or subcontract it to a local company, to help keep the overall costs down.

Neutral Earthing Configuration 

Aurora can provide detailed advice on how a power systems neutrals should be connected to earth at each voltage level, as this is of fundamental importance in ensuring the systems performance and safety. This includes, resistance earthing, reactance earthing, zig-zag grounding transformers, Petersen coils and even operating unearthed. Where appropriate Aurora will also help in selecting the appropriate values for any neutral earthing resistors and reactors.