[ Technical: FAQs ] Need to know?
Each issue, we answers a selection of members’ most frequently asked questions, providing expert guidance and tips. Here, Giuliano Digilio, ECA head of Technical Services, covers key issues relating to inspection and testing equipment
We test secondhand electrical items donated to charity shops. The Regs say that ‘before the test… switches should be put in the “on” position.’ But a lot of modern equipment has an electronic ‘on’ switch that won’t latch unless the supply is on. This means a PAT tester checks the insulation resistance only as far as the power cable termination, and doesn’t check the internal circuit. Should we just note this in the test record, or do we have to fail the equipment?
In cases like this, the only option is to perform an earth bond test and, if possible, an earth leakage test. Not all PAT testers have an earth leakage option, but among those that do are testers in Megger’s latest PAT400 range. With these testers, the most appropriate tests will be the differential earth
Multifunction tester
leakage test for Class I assets, and the touch-current test for Class II assets. When an insulation test can’t be carried out, it’s OK to use an earth leakage test instead. The test energises the equipment, which then allows you to operate the electronic switch. Once turned on, the earth leakage for all circuits is measured. The maximum leakage currents permitted are given in the Code of Practice. You should record the tests performed and the results on form V1.2, and you should add a comment explaining that an insulation test wasn’t performed. Keep up the good work for the charity shops, by the way – it’s always disappointing when they refuse to take electrical equipment that could produce useful income, especially when you know how little it would cost them to have it PAT tested.
I’ve just told my mate that he’s going nuts, but now I’m not so sure! He said he was testing the RCD function on an RCBO. If he connected the tester to the RCBO terminals, it wouldn’t trip, but if he connected the tester at the end of the circuit, the RCBO worked perfectly. And it wasn’t just one RCBO, it was lots of them. I didn’t believe him till he showed me, but it was just like he said. Are we both going crazy?
September 2012 ECA Today 59
SHUTTERSTOCK / VIKTORIYA
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