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 Post subject: RCD Testing
PostPosted: Mon Jun 18, 2018 2:11 pm 
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Hello all.
Quick one for you all out there.
When doing a 30ma RCD test on x 1 setting, it passes on both 36.4 and 26.4. Being new to the game, I thought it only passes if under 30ma?

Hopefully clear.
Thanks


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 Post subject: Re: RCD Testing
PostPosted: Mon Jun 18, 2018 6:37 pm 
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RCD trip times are as follows for a 30mA G type RCD

At x1 within 300ms
At x5 within 40ms
At x1/2 should not trip

Note that at x1/2 most testers only test for 2000ms. There is no reason for this other than at some point they do have to stop the test.

How are you getting on with your tester?


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 Post subject: Re: RCD Testing
PostPosted: Mon Jun 18, 2018 6:59 pm 
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Thanks for your quick response - tester is good considering bottom end of the market - I think.
If you look back at my notes, the higher reading of 36.4 was using the x1 test - not the x5
any thoughts.
cheers


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 Post subject: Re: RCD Testing
PostPosted: Tue Jun 19, 2018 6:18 am 
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Well the RCD is within spec. That is a typical reading I would expect at x1. Note that it is the highest of the readings that you record.


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 Post subject: Re: RCD Testing
PostPosted: Tue Jun 19, 2018 6:53 pm 
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Just a thought tonk.

On rereading your questions I think you might have mixed up mA with ms.

The 36.4 and 26.4 readings you got are the ms that it took to trip the RCD on both cycles (not important ATM) with your tester giving the RCD 30mA of test current (if it is a 30mA RCD).

The x 1 means you are testing at the RCD's nominal rated setting. So for a 30mA RCD the tester is testing at 30mA. The trip times I gave you are the maximum times allowed that the RCD must trip in.

Why not redo the test at x 5 (when the tester is testing the RCD at 150mA) and see what results you get. I would expect lower ms readings.

All the best fella and do ask again if you are not sure.


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 Post subject: Re: RCD Testing
PostPosted: Tue Jun 19, 2018 11:28 pm 
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I had not heard of type G until your post, it seems type G should have at least a 10 mS delay, although it depends which report you read, it makes sense now we can't use type S, but at x1 most RCD's seemed very near the 40 mS mark.

50 Hz = 10 mS between each zero point, so testing each half cycle it could take 15 mS to reach peak voltage on that cycle, so add 10 mS delay then 25 mS could be best result, not missed even one cycle. Even 35 mS is only missing one peak. So the 40 mS limit is in real terms quite tight.


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 Post subject: Re: RCD Testing
PostPosted: Wed Jun 20, 2018 6:55 pm 
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G just meaning general and not time delayed (knowns as S type). I only used the term as the OP will have his tester set to G when testing the RCD.

The 40ms limit is for x5 nominal trip current. It needs to be tight to stop ventricular fibrillation.


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 Post subject: Re: RCD Testing
PostPosted: Mon Jul 09, 2018 9:57 am 
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Hello Only Me, thanks for your guidance over the lasts few weeks, your pointers made me look deeper into my reference books. Good thing is that I passed my NAPIT assessment last Tuesday.
Cheers for now ...


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 Post subject: Re: RCD Testing
PostPosted: Mon Jul 09, 2018 8:57 pm 
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Good luck with it and well done.

There is an old Yorkshire saying "if you have nothing nice to say keep keep your gob shut". I shall then keep my gob shut about NAPIT.


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