Ensuring accurate test results is more than just good practice, it’s a legal and professional necessity. Rob Shepherd explains why test equipment calibration not only ensures compliance and reliability but also safeguards reputations and lives in an increasingly safety conscious world.
For some electrical contractors, calibrating their test equipment rarely crosses their mind. For others, it sits stubbornly at the bottom of the ‘to do’ list and can always wait until next month, or perhaps the next job. Yet calibration is not an optional extra, it is an essential part of professional practice and if you fall into either of these groups, it’s time to give the issue some serious thought.
Why it matters
Let’s be honest, calibration can be frustrating. After spending a substantial amount of money on devices such as multimeters, insulation testers, loop impedance meters and PAT testers to comply with BS 7671 – the 18th Edition of the Wiring Regulations, you then need to spend even more to make sure it’s still producing accurate results! However, in the regulatory landscape that defines today’s electrical contracting industry, calibration isn’t just about ensuring a circuit or appliance is safe, it’s about ensuring that the data you record and present is trustworthy, traceable and defensible.
In a perfect world, having paid for high quality test equipment, it would be great if it could maintain its accuracy automatically and indefinitely. Unfortunately, that isn’t the case and even the most advanced and expensive instruments need periodic calibration, just as a Ferrari needs regular servicing to maintain peak performance. Every instrument, no matter how sophisticated, relies on sensitive internal components that can drift, wear or degrade due to use, age or environmental factors such as humidity and temperature fluctuations.
Danger zone
The dangers associated with uncalibrated or poorly maintained test equipment cannot be overstated. Faulty readings may lead contractors to sign-off on electrical installations that are unsafe or non-compliant with BS 7671.
For example, an insulation resistance tester that reads higher than the actual value could mask a potentially dangerous fault, leading to electrical fires or electric shock risks. Similarly, inaccurate earth loop impedance measurements might result in circuits failing to trip under fault conditions, posing a danger to both users and property. In the worst cases, such oversights can result in injury or loss of life, legal prosecution and irreparable damage to a company’s reputation.
Submitting incorrect test results, even unintentionally, is a serious issue. If it’s your signature at the bottom of a certificate, you’re accepting legal and professional responsibility for the accuracy of those results. Should something go wrong an investigation will look not only at the installation but also at the testing process. If it’s discovered that your test equipment was out of calibration, your results may be deemed invalid and you could be held accountable.
Electrical contractors involved in PAT testing face particularly high exposure in this regard. PAT testing is often performed on a large scale and relies heavily on consistent and repeatable measurements. A small calibration drift in insulation resistance or earth continuity readings could easily lead to a dangerous appliance being passed as safe or a perfectly good one being unnecessarily failed.
Rules and regulations
The accuracy and traceability of calibration are governed by a range of standards and guidelines. The Electricity at Work Regulations 1989 and the Part P of the Building Regulations establish the legal framework for electrical safety and certification. While these regulations don’t specify exact calibration intervals, they do require that any measurements taken are accurate and that appropriate equipment is used.
BS 7671 requires that test equipment used to verify compliance should be ‘suitable for the purpose’ and ‘maintained in good order’. The IET Guidance Note 3 goes further, recommending annual calibration of test instruments supported by a valid certificate of calibration traceable to national or international standards. This is usually via the United Kingdom Accreditation Service (UKAS). This traceability ensures that the results can be compared to a recognised reference standard and without it any claim to accuracy is little more than an assumption.
Professional accreditation bodies and certification schemes, such as those from NICEIC, NAPIT and the ECA, also stipulate that contractors must use calibrated test instruments. During audits and assessments, proof of up-to-date calibration certificates is often required. Failure to produce valid calibration documentation can result in non-compliance issues, suspension of membership or loss of certification.
Easy does it
Traditionally, getting test equipment calibrated meant sending it back to the manufacturer or using a third-party calibration house. While these are still both valid options, they come with a common drawback – downtime. While a tester is away being calibrated, the ability to perform testing and certification work is effectively on hold. This can cause scheduling delays, lost income and frustrated clients.
In recent years several manufacturers and calibration service providers have taken steps to make the process easier and faster for contractors. Some offer on-site calibration services, where technicians visit a contractor’s premises and perform the calibration there and then. Others provide exchange, whereby you send in your tester and receive a calibrated replacement immediately, minimising workflow disruption. There are also mobile calibration units that travel to trade shows and events, allowing contractors to get their equipment checked and certified on the spot.
Increasingly, digital record keeping and software driven testing solutions are being paired with calibration management systems that automatically track calibration dates and alert users when a device is due for calibration. These advances make compliance easier but they don’t remove the need for the underlying discipline of regular checks.
Get the message
Calibration isn’t just a box-ticking exercise. As regulations tighten and clients become more informed, being able to demonstrate that your equipment is properly maintained and calibrated is not just good practice but a competitive advantage. So, if your tester hasn’t seen a calibration lab for a while it’s time to act. Calibration may seem like a small detail, but it’s one that underpins every measurement you make, every certificate you sign and every installation you leave behind.
Contributors
Rob Shepherd (author)
Rob is Consulting Editor for InstallerELECTRIC. He is a well-respected journalist with a strong history in the electrical sector.
