RCD testing

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RCD testing

Postby ansellrk » Wed Jun 20, 2012 2:37 pm

Hi,

I've been PAT testing for several years now but have only just been asked to test ten RCD's. The cleaners at the company have them for plugging thier vacuum cleaners into and the company want them tested along with the vacuum cleaners. So, I have a Europa Plus which doesn't have a "TEST RCD" option... what tests can I do?

I know I can do a visual, ensure they trip and I suppose I could do a polarity check but I can't test the trip time to prove it is within limits...although I'm not sure the regulations require this anyway?!

Any advice, support or put downs will be gratefully recieved.

Rob
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Re: RCD testing

Postby safe + sound » Wed Jun 20, 2012 5:10 pm

Hi Rob

The current 3rd edition of the code of practice says the RCD should be checked for correct operation by plugging it in, switching on and then pushing the test button, it must trip to pass. It then recommends a timing test.
(15.10.2 page 79)

I do a visual, earth continuity and an insulation test whilst holding down the 'on' button with an insulated screwdriver, followed by the timing tests with a Primetest 350 which also proves polarity when its powered up.

I guess its up to your customer to decide if they want timing tests.
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Re: RCD testing

Postby southseas » Fri Jun 22, 2012 7:04 am

I test around 50 - 100 RCD Leads and RCD Protected power boards a month, about 4% of them either do not trip at all, or do not trip within 300mS at their Rated Trip Current. I'd invest in an RCD Tester that allows you to check that they trip with their rated trip current on both sides of the sine wave (had ones that with trip one side but not the other) within time limit for RCD type.

Do the Trip tests after the visual, then use your Europa Plus to check earth bond, IR, and Polarity and manually enter Trip time in comments (which will show up in your results report)
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Re: RCD testing

Postby Grizzly » Sun Jun 24, 2012 6:40 pm

southseas wrote:... about 4% of them either do not trip at all, or do not trip within 300mS at their Rated Trip Current.


Portable RCDs (plug-in, wireable plug and in-line) are made to BS 7071.
RCDs to this standard should not trip at 0.5x In, should trip within 200ms at 1x In, and trip within 40ms at 5x In (all these for both sides of the waveform). Details here: http://www.greenbrook.co.uk/pdf/pbcatpg23-24.pdf (part h)

I'd invest in an RCD Tester that allows you to check that they trip with their rated trip current on both sides of the sine wave (had ones that with trip one side but not the other) within time limit for RCD type.


Definitely better to have one of these, as PAT testers that have an RCD test function tend not to offer the full functionality.

Do the Trip tests after the visual, then use your Europa Plus to check earth bond, IR, and Polarity and manually enter Trip time in comments (which will show up in your results report)


Personally, I wouldn't perform an IR.
BS 7071 devices will not reset if 230V mains isn't present, so the only way to make sure a 500V IR test might work is to hold the reset button in (as safe + sound mentions), and even this won't work properly on certain brands.
Instead, run a leakage/PCC test. This provides 230V mains, so the device can be reset, and the result will be meaningful.
Similarly, I'm not sure a polarity test will work unless the reset button in held in, and then not always.
C&G 2377 -01 & -02
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Re: RCD testing

Postby Jim Wallace » Tue Jun 26, 2012 8:48 pm

Hi Grizzly

Southseas is based in a far off land down under where they have different trip time limits for RCDs.

Agree 100% regarding IR testing - a powered leaakge test is a much more robust way of checking the insulation. A polarity test can be performed by powering your PAT from the RCD as the PAT will verify the correct polarity of the incoming mains supply.
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Re: RCD testing

Postby Grizzly » Wed Jun 27, 2012 12:53 am

Jim Wallace wrote:Southseas is based in a far off land down under where they have different trip time limits for RCDs.


Ah, fair enough.
I'll let him off just this once then :D
C&G 2377 -01 & -02
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Re: RCD testing

Postby southseas » Thu Jun 28, 2012 7:22 pm

Ah, fair enough.
I'll let him off just this once then :D

Thanks Grizz :) Lot of sparkies poo poo TnT as being not worth the effort down in this neck of the woods in the mistaken belief that RCD's are next to God in terms of infallibility- but as I said above, when you test them like all devices, a number don't work/don't work within their rated times etc etc.

I test a lot of RCD's fitted to Outlet Boards, for ones used on Construction and Demolition sites, each outlet is individually wired, hence the need to check the polarity multiple times along with an Earth Bond on each
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Re: RCD testing

Postby ansellrk » Tue Jul 03, 2012 10:48 am

Thanks for all the response. After careful consideration I believe an RCD tester is the way to go, just to cover my own backside!
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