How to safely and accurately use electrical testing equipment
Electrical testing can be just as hazardous as electrical installation, and it adds a layer of complexity to the fundamental challenges of working safely with electrical current. There’s an added risk from the voltage of the test equipment itself, or from any device that stores energy such as an uninterruptible power supply (UPS).
The main legislation relating to electrical testing activities is the Electricity at Work Regulations (EWR). The Health and Safety Executive point to Regulation 4 which requires work on electrical systems to be carried out in such a way that it doesn’t give rise to danger – http://www.hse.gov.uk/pubns/indg354.pdf. Naturally, this includes testing of the system and the use of accurate testing equipment.
To test circuits safely, for example, electrical engineers need to be following safe working guidelines. That means checking that the test equipment itself is both safe and appropriate for the job it’s going to be used on.
Isolate the equipment and use accurate instruments
The EWR legislation states that electrical equipment must be isolated from the supply before work is carried out. Then the engineer needs to check and confirm that the circuits being tested are properly isolated.
Because safety reports and certificates are often issued as a result of tests that have been carried out, it’s essential that the test results are accurate. Therefore, the testing equipment must be checked to confirm that it is giving correct and consistent results. One way of doing this is to cross-check with other testing equipment, then compare the results. For example, instruments testing earth fault loop impedance can be cross-checked against a specific socket outlet. However, for full assurance, the instruments should be laboratory tested and accurately calibrated, with the calibration confirmed by a certificate. A log of test results should be maintained.
Advanced equipment has safety designed in
The most advanced equipment has inbuilt safety systems that make testing and maintenance work easier and safer. For example, the Eaton UPS Systems http://www.cppsales.com/ have an extra large static switch which is equipped with an ultra-rapid fuse, to deliver safe working in any situation. Safety is also enhanced through a backfeed contactor, which eliminates the need to make additional instalments.
The combination of more safety features in electrical equipment and safe working procedures for electrical testing should reduce risk for all operators and engineers.