I found some archive footage of Matthew on-site testing an RCD and we know under the 18th Edition
Amendment 2 of BS7671's wiring regulations that all RCDs regardless of their type are tested as
if they're an AC RCD and at one times I Delta N and does this video vindicate the decision under
that amendment to test RCDs in that way I really would be interested in your thoughts and comments
so please leave them below I'm just going to carry out some testing on the consumer unit in the in a
garage it's fed from circuit number five in the house on a 20 amp circuit as you can see it's an
armored cable feed coming in and we've got socket circuits on a 16 amp breaker and lighting on a six
amp breaker and obviously we have the RCD so I'm just going to confirm the Z DB or the Zs
for circuit number five so that's reading 0.46 ohms which we're quite happy with that now we're
going to test the RCD and it's uh 30 milliamp so we turn the RCD the set into 30 milliamp
and we're going to go on the half times test first
and the little symbol there is has come up for the AC so let's test it shouldn't trip
again it hasn't tripped so we turned back to 180 degrees and test it again
it hasn't tripped so now we're going to go on to the one times test and it reverts
back to the zero degrees so press the test button and as you can see it hasn't tripped
so I'm just going to test that again
but it hasn't tripped so we'll turn it on to the 180 degrees
once again it hasn't true so that's on the one times but it's obviously failed let's try it on
the five times test that's tripped within 18.6 let's turn it back on on 180 degrees
28.9 so that's tripped that's that's passed on the five times test because it's under 40
milliseconds but it's obviously failed on the one times test let's just check the ramp test
and this should be below 30 milliamps and it's written at 27 milliamps thanks Matt
so there we have it has that proved that BS7671 has got it right testing all our
RCDs regardless of their type as if they're AC and test them at one times I Delta N to prove
that they are functional for other great videos on testing check out the link on the screen now