Soil Resistivity Surveys
The starting point to designing any Earth Electrode System is to determine the resistivity of the ground that the earthing is to be installed in.
It is of vital importance that a ‘clean’ set of soil resistivity measurements are taken, as these readings have a direct influence on the quantities of Copper Conductor that are to be installed in the ground, too much and the system is over-engineered and unduly expensive, too little and the resultant levels of Rise of Earth Potentials may be lethal.
We only use the Megger DET2/2 earth tester, a high-end test instrument capable of filtering out unwanted electrical noise that may foul the results gained.
Our team of Engineers and Technicians will attend your site and carry out a full electrical assessment of the ground. The raw data is processed using a bespoke module RESAP built into the CDEGS software package, this enables the formulation of a multi-layered soil model, allowing for a much more efficient Earth Electrode System Design going forward.
Many companies are able to use longhand calculations to provide a uniform soil model, only software such as CDEGS can give multi-layered soil models, this multi-layered soil model allows us to tailor the earth electrode system to the specific site requirements offering a safe efficient approach to the design process.
All work is carried out by our trained and competent Engineers and Technicians in accordance with BS 7430:2011+A1:2015 (Code of practice for protective earthing of electrical installations) and BS EN 50522:2010 (Earthing of power installations exceeding 1kV a.c.)
Earth Electrode System Design
The three main areas to analyse with any Earth Electrode system are the Touch, Step and Rise of Earth Potentials (RoEP) also known as Earth Potential Rise (EPR or Ground Potential Rise (GPR).
We will liaise with the DNO or Electricity Supply Company on your behalf to gain all the required ‘Point of Connection’ data for your new electrical connection.
Using the Soil Resistivity data, we produce a conceptual earth electrode system layout based on your existing plant layout drawings and analyse the associated voltage contours using either the MALT or MALZ module of the CDEGS software. Graphical plots are produced using the CDEGS software that visually identifies any ‘hot’ spots around the site that may need further design time.
These Touch, Step and Rise of Earth Potential levels are assessed, and only when they are within safe limits will we pass this design for construction.
Further calculations will be carried out to determine whether the site may influence other electrical installations under fault conditions and from that we can determine the site ITU classification as either HOT or COLD.
Only once we have confidence that the design is parameters are met, a full ‘for construction’ style drawing will be produced.