GAS DETECTION & MONITORING
TOP TESTER TIPS
Simon Wood, UK Wholesale & Distribution Sales Manager at Megger UK, provides some top tips for employers searching for the ideal gas detector.
Buying testers is an important investment in the future of your business. Making an informed decision now may stop you regretting your investment in a just few short months.
You’ll need testers that will check earth loop impedance, RCD timings, insulation resistance and continuity, plus something to check whether cables are live before you work on them and to help trace them, as well as a general-purpose multimeter.
The testers can be single function instruments or an all-in-one multifunction tester (MFT). Most contractors choose all-in-one testers because they are more economical in terms of initial cost, storage space and the on-going cost of calibration. To support their MFT, contractors will usually have a volt finder and an electrician’s multimeter, both of which are relatively inexpensive products. Single function testers are favoured by larger organisations with a number of workers in the field.
WHAT SHOULD YOU LOOK FOR WHEN YOU BUY A TESTER?
Calibration certificate Testers aren’t cheap; so make sure that the one you get is ready for work as soon as it comes off the shelf. In short, choose a tester that comes with a calibration certificate.
Three-phase safe Be sure to check that your tester
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is three-phase safe - generally the manufacturers make this clear. Many are not, however, and if you connect them across the phases, they’re likely to make a nasty muffled bang as they expire.
Physically tough Testers must be tough enough to withstand the drops and bashes that are part of being on site. Rubberised over-mouldings, as well as face and screen covers are useful to reduce the risk of the tester being accidentally damaged.
Display You’ll be copying information from the display so it helps a lot if it’s easy to read and displays only the necessary information.
Switched Probes When you’re insulation testing, a test button on the probe itself is useful as it means that you can keep your eye on the test piece rather than groping around for the test button.
Non-trip loop testing Being able to do earth loop impedance testing without tripping RCDs and 6 A MCBs is a must. Most testers have a low-current non-trip three-wire loop test, which is good for most applications, but it’s now also possible to get MFTs that do a two-wire non- trip test as well.
Make sure your tester starts the loop test automatically as soon as the probes are on the test piece. It’s also
worth choosing a tester that has a high current loop test function for use on circuits that aren’t RCD protected.
Auto RCD Choose an RCD tester that does automation RCD testing. As you know, there are five tests you need to do on an RCD: ½I, I at 0º and 180º, and 5I at 0º and 180º. With Auto RCD testing all you do is plug the tester in and set the test running, go down to the RCD, reset it four times when it trips, then return to the tester to collect your results. If you don’t have auto RCD testing, you have to make four trips to the RCD which wastes valuable time.
RCD ramp test This simple test can save hours when you’re trying to work out why an RCD keeps nuisance tripping. The ramp test slowly increases the current until the RCD trips, and then displays the tripping current in milliamps. If the trip current is too low, you know the problem is with the RCD and that you need to replace it.
Safety shutters The better testers have a shutter arrangement to prevent you making potentially dangerous mistakes.
A WORD OF ADVICE
Choose a tester that’s easy to use. That basic simplicity will make it much more likely that you and your tester will have a long and profitable life together.
www.megger.co.uk www.tomorrowshs.com
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