Electrical earthing system testing

soil resistivityElectrical earthing systems are required to protect life, assets and liability from the threats of fault electrical current. This being the case it is unsurprising that it is important to verify that such systems meet the requisite performance requirements. Earthing Services is recognised as a company able to certificate such systems by end clients or third party approval bodies such as DNOs and regularly undertakes such services.

This variety of service is either one of the last that they require or one of the first depending upon the age of the electrical earthing system in question. In the cases where an electrical earthing system is being installed as new it is likely that Earthing Services will have surveyed, designed, specified, the quality of installation undertaken by others audited, and then finally to the testing and commissioning phase in question on this page. Instances of existing electrical earthing systems being tested for ongoing suitability, or to verify its capacity due to changes of the site’s usage, it is possibly Earthing Services’s first presence on site; potential follow on services may include re-specification of any necessary enhancements to the electrical earthing system, preparation of remedial work documentation and method statements, then further testing and commissioning exercises to verify and remedial works or enhancements function in accordance with the agreed scope of works.

On occasion customers contact Earthing Services advising that their electrical systems have been behaving in unforeseen or even destructive ways. On such occasions testing the electrical earthing system often yields a great deal of useful information and in some instances evidences the problem immediately.

Earthing Services engineers undertake electrical earthing system tests for numerous customers on a regular basis, and these services have been conducted all over the world. Feedback from a number of new customers (who have previously subcontracted electrical earthing system testing to other companies), has brought to our attention that Earthing Services’s turnaround time from the commencement of testing to the client’s receipt of processed results is faster than competitors by a considerable margin.

Prior to testing: planning and geographic determinations

From the moment the company receives an order which requires an electrical earthing system test Earthing Services engineers commence the desktop planning stage of the project. Our trained team knows how to assess the practicality and usefulness of a given area when it comes to undertaking electrical earthing system testing, and this can begin using topographical data, location coordinates, and plotting technologies.

The area required for testing varies depending on the size and variety of test being undertaken. This is critically important for tests to yield meaningful data and it is also the aspect which inexperienced or under qualified companies most regularly misunderstand. The proximity of the test route to the system under test must exceed the influence of the system in question otherwise the data set will be compromised.

Despite these seemingly stringent constraints due to Earthing Services’ commitment to its customer base, the company’s engineers have always obtained accurate, meaningful, data that will define the electrical resistance characteristics of a site. The initial desktop survey enables a decision to be made about testing locations in advance as well as strategic “back up” sites in the event that the primary locations are unavailable. Larger systems, requiring larger test routes are highly likely to cross property boundaries and as such will result in customers obtaining the necessary permissions and cooperation of impacted landowners.

Earthing Services is a rarity in its thoroughness with this aspect of planning, but this contributes to the success the company enjoys in terms of its performance. Clients are safe in the knowledge that if Earthing Services engineers attend a site they are going to be trained, experienced, well-briefed, and focused on achieving the common goal of obtaining a useful, and meaningful certification for the site.

Prior to testing: development of task specific documentation

When a company regularly undertakes the same variety of service it is not uncommon to see standard method statements, risk assessments, and other documentation referenced or presented to a client; Earthing Services is different in this regard. The normal workpack that site engineers receive in advance of travelling to site includes task and location specific method statements, which will detail on special measures or precautions for the site; task and location specific risk assessment, which will identify hierarchies of potential hazards, and control measures; satellite photographs, topographical drawings, and any applicable construction drawings for primary, secondary and even tertiary testing options and any other required project specific documentation. Earthing Services takes planning these activities very seriously because the data obtained from electrical earthing systems is vitally important.

Prior to testing: Equipment check and preparation

A company could use the right method, have a wonderful docket of information and planning, but if the equipment that they send to site is not capable of obtaining an accurate reading then the whole process is deeply flawed. Earthing Services is proud to be different. All testing instrumentation and ancillary equipment is calibrated and maintained and as such there is 100% confidence that the provision of resource to testing engineers is going to get the job done. When it comes to testing instrumentation, despite the claims of many, every device is not the same, and every device does not perform in an equivalent manner to everything else on the market. Earthing Services has undertaken its own research and trialing with an array of brands and varieties of testing equipment and has come to its own conclusions. The testing instruments sent to site are not only calibrated they are also able to test significantly large facilities such as power stations, and do this to a very high level of accuracy even in challenging environments; they may be expensive, far more so than many companies would send to site for an electrical earthing system test, but the Earthing Services Technical department is of the opinion that it makes the most sense to put the best, most reliable and accurate testing equipment at the front end of a project when it can contribute the most to providing a safe, correctly specified, economically installed electrical earthing system.

Testing activities: Travel and initial audit

Earthing Services testing engineers recognise that their work begins whilst they are still travelling to a site. Visual assessments of landscapes can provide a trained eye with a wealth of information that will contribute to the portfolio of evidence that is sent back to the office for processing. Being able to identify and interpret landmasses through their relationship to the rest of their environment is incredibly useful. Questions that occur to engineers during their approach include examples such as, “what is the relative height above sea level?”, “has this area been subject to erosion?”, “has this area seen substantial landscaping or earth movement, which may have disturbed or disrupted the natural tiering within the earth?”, “has the weather been particularly wet, cold, or arid, recently?” and all of the thoughts these sorts of questions prompt help inform the later analysis of data.

When the engineers arrive at site they may well have to be inducted, receive a briefing, or hold a meeting with the client’s representatives, and all of the time they will be evaluating how the activity on site, both current and historic, may have impacted upon the sub-strata. Prior to setting up the electrical earthing system testing it is common for Earthing Services engineers to visually inspect the area, including assessments on local flora and fauna. Mature trees or sub surface agricultural elements can distort or bias electrical resistance within the ground and as such must be avoided and “reading” the landscape is something that Earthing Services engineers are trained to do.

Testing activities: electrical earthing system testing

Undertaking effective testing activities verifies electrical earthing system performance, and as such this is the most important stage in the process. For the majority of electrical earthing system tests Earthing Services engineers will have at least two Megger DET 2/2 devices with them to undertake and verify the test; these testing devices are quite expensive and other companies frequently buy alternative instruments and advise that they perform comparably, however this has not been proven to be the case in the experience of a number of Earthing Services engineers. Earthing Services demands the best performance from its equipment because that is the standard of service it wishes to offer its customers.

These activities frequently take place on active construction sites and as such it is not uncommon for testing cables to show signs of use, however Earthing Services always ensures that equipment is calibrated, ready for use, clean as far as possible, and also with all cables carefully prepped on their drums or other suitable method of carriage. Earthing Services engineers will never attend site with a “birds nest” of cables or testing devices that are not fit for the task in hand.

A test will require a suitable connection with the electrical earthing system in question, and then extend cables to establish a reference earth some distance away (determined by the size of system under test). The methodology used will determine the method of calculation and the characteristics of the intervals at which readings and measurements shall be taken. Many tests may look identical to the untrained eye they may differ quite significantly and interpreting the values obtained requires the assessment of experienced engineers.

Testing activities: methodology – Slope, Fall Of Potential (FOP), Dead Earth

Different electrical earthing systems may require different testing methodologies to yield the most meaningful information from the site. It may also transpire that the client, or third party authorising body have specific testing requirements and will not accept data obtained by any other method than their preferred. Fortunately Earthing Services engineers, both in-house and site based, have voluminous experience with all of them.

Testing activities: Transmission of data set

As soon as Earthing Services testing engineers have completed their activities on site they aggregate it into a package of information, comprising everything that they have obtained and transmit it back to the servers at the Nottingham office. Using specialist software the package of information is decoded and at that point work on computation can immediately begin. This aspect of Earthing Services’ electrical earthing system testing is one of the most popular because it circumvents any delay, or potential loss of paper based documentation.

Testing activities: Computation of data set

As indicated by the previous stage, electrical earthing systems cannot be certified simply from an engineer turning on a test instrument, the data needs to be analysed to ensure that the information evidences effectiveness. Possessing knowledge of location of test and the geographical characteristics of it enables Earthing Services earthing engineers to fully assess compliance and determine the performance attributes of the site. This evidenced performance is then compared to the theoretical performance value identified at design stage, which will yield information as to the quality of the installation.

Testing activities: Transmission of completed report

Once all computational activities have been resolved a report is prepared for issue to Earthing Services’s customer. In the event that the customer in question used Earthing Services for the design and specification phase of the project then it is highly likely that the original design report will be revised to enable direct comparison between the theoretical value and the achieved value.

If you would like to learn more about Earthing Services’s electrical earthing system testing then please feel free to get in touch via the contact page, or call the Nottingham office