A. N. Wallis & Co Ltd are one of the world’s leading Electrical Earthing & Lightning Protection component material manufacturers and suppliers. To complement our highly successful material supply business, we also offer a complete Electrical Earthing Design Service.
Wallis is accredited to ISO 9001:2015 Quality Management System for our design and manufacturing services and is also accredited to ISO 45001:2018 for our Occupational Health & Safety Management System. We are also operating a compliant ISO 14001 Environmental Management system.
We are also accredited to design for and work on the Network Rail Infrastructure under the RISQS scheme, as well as being certified members of Constructionline, UVDB, Supply-Line & CIRAS.
Our aim is to design and supply cost-effective Earth Electrode, Lightning Protection and Surge Protection Systems, using the minimum material to produce the best possible results.
Earth Electrode Systems are a critical part of any electrical system, yet are often seen as inert and may sometimes be dismissed as cost-saving or forgotten about until a later stage of the project. But should these systems fail due to incompetent design or the use of cheap substandard components, the resulting events may be catastrophic or even lethal.
Our team of highly experienced professional Engineers & Technicians use the world’s most up to date Electrical Earthing Analysis software package CDEGS to assist in the Earth Electrode System Design process. CDEGS is now recognised as the industry standard earthing design analysis software in the UK and in many other parts of the world.
Our Earthing Design Manager, Simon Sorsby, is a Chartered Engineer and one of a handful of European Engineers Trained to SES Tech’s Level 1 CDEGS Training course in Montreal, Canada. Simon has worked for some of the UK’s largest Companies as well as Distribution Network Operators and Specialist Contractors specialising in the High Voltage (HV) Electrical Transmission and Distribution Industries.
Our Earth Electrode System Designs not only comply with the relevant National and International Standards, but also follow the ethos of the UK Governments’ Construction, Design & Management (CDM) Regulations 2015.
Some of the areas we are working in are:-
Electricity Transmission & Distribution Networks
Electricity Generation sites inc Renewables (Solar, Wind, Anaerobic Digesters)
Process Plants Static Earthing
Rail Traction Substations
Rail Functional Earthing
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 (Code of practice for protective earthing of electrical installations) and BS EN 50522:2010 (Earthing of power installations exceeding 1kV a.c.)
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.
Once the system has been fully installed, confirmation should be sought as to whether the design resistance and installed system resistance are comparable. This is done via direct measurement using one of a few different methods of testing such as the Fall of Potential or Slope method of testing.
To gain a true measurement of the installed Earth Electrode System, it is necessary to run test leads many tens of meters away from the system under test, avoiding any buried metal objects or overhead power lines. The Engineer attending site will evaluate the area available for testing and determine the best method of test for that specific Earth Electrode System.
Once the test is complete using our powerful and accurate test equipment, a certificate of compliance will be issued, many Electricity Companies will not energise your site without this certificate.
Like any other part of the electrical system, an Earth Electrode System must be inspected and tested at regular intervals.
BS7430:2011 recommends visual inspections of Earth Electrode Systems on an annual basis, with full testing and maintenance carried out at a period not exceeding 5 years.
It is unlikely that the electrical system will be de-energised whilst the Earth Electrode System is inspected and tested, and leakage currents to relatively high and lethal levels may flow even under ‘steady state’ normal operating conditions. It is therefore essential that only trained and competent Engineers and Technicians complete testing on Earth Electrode Systems.
A. N. Wallis is able to offer both annual visual inspection and full testing and maintenance services in line with the British Standard. Our trained and competent staff are able to identify and document any deficiencies in the installed system and provide a report accordingly.