Ash Mohammed, Managing Director at Di-Log, stresses the importance of using a fully featured, premium voltage testing unit.
It’s always tempting to go for the lower cost option; this doesn’t have any serious consequences in most areas of life, but when it comes to equipment that you rely and depend on to provide verification of testing for third parties, you need to be rather more selective then simply opting for the lowest price.
The chances of the more expensive (quality) item will turn out to be the lowest cost in the long term.
If the cheap meter breaks down on site it will result in at the very least a trip to your wholesaler to get a replacement and if it has to be ordered then it may be many days before you can resume work. The cost of obtaining a replacement and the lost time can therefore far outweigh any initial saving made on the purchase.
The accuracy and repeatability of meters can make a huge impact in terms of the speed of carrying out testing and inspection, for completing certificates and for fault finding/diagnosis. The cheap meter may well be adequate for non certification work or applications where approximate readings are adequate, but for more exacting applications such as verification to safety standards or fault finding diagnosis in complex installations, there can be no substitute for using quality instruments. This is especially valid when providing testing services for third parties and issuing test certificates for works carried out. In the event of injury, damage to equipment or fire, it is the certification (and the accuracy of the tester) that may be your defence in a court of law.
Cost cutting can sacrifice on the functionality of the tester. This may not be apparent when looking at the specification in the catalogue, or on handling the unit in the wholesalers. It is only when you are in the field that you might realise if corners have been cut to get the unit built down to a price. There will be functions and features on quality instruments that can make testing quick and simple, which can add up to a great deal of time saving on site. The extra price paid will be recouped many times over the life of the instrument.
Digital multimeters can be bought for as little as £5. It is a certainty that meters at this price level are built to a budget rather than with safety and performance standards in mind. We have all selected the wrong setting or range, but with a meter that complies with all the relevant safety standards the damage should be no more than a blown fuse or in the worst case scenario internal damage that is contained within the instrument casing.
The international safety standard IEC 61010-1 defines the various requirements for test and measuring equipment specified for testing electrical installations (up to 1,000 volts). IEC 61010-1 specifies categories of overvoltage based on the distance the piece of equipment is from the power source. Higher categories are closer to the power source and require greater levels of protection. Test procedures take into account three main criteria: steady state voltage, peak impulse transient voltage and source impedance.
Having selected a quality instrument that complies with IEC 61010 and checked that it is suitable for the particular application, some thought needs to be given to the ongoing maintenance of the tester to ensure years of happy testing. This can be achieved by observing the manufacturers recommended calibration/service recommendations with regards to the formal calibration and by keeping informal checks on the accuracy of the tester, for instance by cross-referencing to other instruments that the business may own or testing on a designated circuit in the office or home. There are also now a number of test instrument manufacturers producing calibration check boxes, which enable the contractor to check instrument accuracy in the office or in the field.
Whilst safety is everyone’s responsibility. Ultimately it is for the individual to adopt safe working practice; the selection of quality test equipment from a reputable manufacturer can go along way to ensuring the safety of the user, accuracy and integrity of test results