Hi All,
Where an RCD is contained within a piece of electrical equipment such as an EV charger, is it still a requirement to test the RCD every 6 months in line with BS 7671 or are the intervals now the decision of the manufacturer of the piece of equipment containing the device?
Regards
Mark
Megger advert from three years ago, encouraging you to upgrade the tester you already had, if you did then presumably it now needs a software upgrade to reduce the rate of rise on the RCD ramp test to get a reasonable test result when using it to try and test a RDC-DD, because the extended tripping period means the tester will miss its target, giving a test result of 8 mA when the device actually started tripping at 5.5 mA, allowing the tester to give a test result of 6 mA so you can say it passes.
The trip time for a Zappi RDC-DD is 900 mS, but the product standard allows up to 10 seconds (10,000 mS) at 6 mA and during the tripping period the RCD ramp test just keeps on ramping up and misses the target, giving the test current at the end of the test, not the current that started the tripping process.
Without guidance from the EVSE manufacturer it’s not actually possible to really determine if the test results you get are actually indicating a fault or not if for example you get a test result of 8 mA as stated in the article on the Zappi website.
Just because you have a meter that has had its software tweaked to get a pass when testing a Zappi EV charger doesn’t mean you know it will work with all EV chargers, because other EV chargers may have a longer trip time but still comply with the product standard.
So, like Type A RCD testing, to fully test RDC-DD you need a good understanding of the product standards, the individual manufacturers specifications for each of their products and the specific testing requirements for each individual device you are testing.
I might get shot down in flames and told I have have completely misunderstood the Zappi article and its implications, but as I understand it there are extremely good reasons why in the COP 9.6.6 says BS 7671 does not require tests of RDC-DD to be conducted, although it may be useful for fault-finding purposes, or where the functional test is specified in the EVSE instructions.
Megger advert from three years ago, encouraging you to upgrade the tester you already had, if you did then presumably it now needs a software upgrade to reduce the rate of rise on the RCD ramp test to get a reasonable test result when using it to try and test a RDC-DD, because the extended tripping period means the tester will miss its target, giving a test result of 8 mA when the device actually started tripping at 5.5 mA, allowing the tester to give a test result of 6 mA so you can say it passes.
The trip time for a Zappi RDC-DD is 900 mS, but the product standard allows up to 10 seconds (10,000 mS) at 6 mA and during the tripping period the RCD ramp test just keeps on ramping up and misses the target, giving the test current at the end of the test, not the current that started the tripping process.
Without guidance from the EVSE manufacturer it’s not actually possible to really determine if the test results you get are actually indicating a fault or not if for example you get a test result of 8 mA as stated in the article on the Zappi website.
Just because you have a meter that has had its software tweaked to get a pass when testing a Zappi EV charger doesn’t mean you know it will work with all EV chargers, because other EV chargers may have a longer trip time but still comply with the product standard.
So, like Type A RCD testing, to fully test RDC-DD you need a good understanding of the product standards, the individual manufacturers specifications for each of their products and the specific testing requirements for each individual device you are testing.
I might get shot down in flames and told I have have completely misunderstood the Zappi article and its implications, but as I understand it there are extremely good reasons why in the COP 9.6.6 says BS 7671 does not require tests of RDC-DD to be conducted, although it may be useful for fault-finding purposes, or where the functional test is specified in the EVSE instructions.
