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Wessex CP-5 Earthing Renewals

RPS designed a new  Substation earth farm at Tolworth  Substation. The 33kV Substation was deemed a hot site by Network Rail with a ROEP at 1,072V. RPS undertook a comprehensive survey to identify the existing earthing and bonding arrangements of the Substation, in addition we undertook the following tests –


  • Fall of potential test to determine existing system earth;

  • Double clamp stakeless method to determine local earth;

  • Soil resistivity measurements using the 4-pole Wenner method;

  • Soil analysis test.

RPS then used the CDEGS software package to accurately design a new earth farm, where ROEP, step and touch potential voltages are calculated, in addition we identified any transfer potential issues regarding a steel palisade fence.  RPS engaged with the contractor and Network Rail to ensure a valued Engineering approach was used for design and construction, which met the requirements of BSEN-50122-2. Once the new earth farm was installed the ROEP was calculated at 245v.


RPS have undertaken 24No. Wessex earthing designs for McNicholas.

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