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RCD test results


MalcyB

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HI all.

I tested an RCD yesterday and got these results.

1/2x 300ms

1/2x 300ms

1x 203ms

1x 11ms

5x 11ms

5x 19ms

Could anyone tell me a reason why the 1st 1x delta test is so high?

Thanks

Malc

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may be because its never been tested before?

did you run the tests again?

and did it trip at 300ms for 1/2 x or not trip?

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HI all.

I tested an RCD yesterday and got these results.

1/2x 300ms

1/2x 300ms

1x 203ms

1x 11ms

5x 11ms

5x 19ms

Could anyone tell me a reason why the 1st 1x delta test is so high?

Thanks

Malc

These results are not unusual, you should always take readings...[as you did]

at least two times.[i personally go for a third ]..usually on 180 degree Phase shift.....Sticky switching mechanisms problems are then eliminated.

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These results are not unusual, you should always take readings...[as you did]

at least two times.[i personally go for a third ]..usually on 180 degree Phase shift.....Sticky switching mechanisms problems are then eliminated.

All I will say is that you only get one chance for the RCD to trip in the event of a fault!!

IMO.... if it doesn't trip the first time (within limits) then it's a fail

:coat

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All I will say is that you only get one chance for the RCD to trip in the event of a fault!!

IMO.... if it doesn't trip the first time (within limits) then it's a fail

:coat

Dont agree with that one NOZ ! Sometimes these RCDs have not been operated for years and after a couple of trip tests they are back to spec.

if people tested them Quarterly ,as recommended, then it wouldnt be a problem,in practice this doesnt happen ,but following the trip testing its back within spec as the test meter results verify .

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Dont agree with that one NOZ ! Sometimes these RCDs have not been operated for years and after a couple of trip tests they are back to spec.

if people tested them Quarterly ,as recommended, then it wouldnt be a problem,in practice this doesnt happen ,but following the trip testing its back within spec as the test meter results verify .

But in real life what is actually going to happen? If it's not tested and it doesn't disconnect in time someone could die.

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But in real life what is actually going to happen? If it's not tested and it doesn't disconnect in time someone could die.

but the problem being, in real life, RCD's should be tested regularly. which should avoid the problem of sticking. but people dont do this, so it may not operate when needed. what we need is an RCD that works like an MCB, in that it doesnt need tested (or open/closed) often

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but the problem being, in real life, RCD's should be tested regularly. which should avoid the problem of sticking. but people dont do this, so it may not operate when needed. what we need is an RCD that works like an MCB, in that it doesnt need tested (or open/closed) often

This is why I am not happy with the 17th edition regs being so heavily reliant on RCD's and less reliant on supplementary bonding.

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Thanks for the answers.

I will be going back there on Tuesday so I will do the test again and compare results.

The board is an older wylex board with the rcd protecting all the curcuits.

Malc

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Malc,,

While your results are a little higher than you might expect, they are within the limits set out in the BRB

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I do not like the fact that a RCD that is used as additional protection "may" fail simply because the reccomended testing intervals are not adhered to.

I have rcd's in my home been there for about 10 years now, tested? NEVER. and I am an electrician. If you work from home I suppose your monthly checks for calibration would test the rcd's, but if you work from an office or unit then the tests are carried out there.

People will not carry out the checks, often although the information is provided they will forget, or simply not bother, there is then a risk that under a fault the rcd will NOT operate within the required time.

If this where to happen, and god forbid a fatality occured, who would be to blame?

Unfortunately it would be the owner, because the manufacturer of the rcd will undoubtedly say, because the required testing was not carried out, failure is down to the owners.

I think this is shamefull.

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got to admit the RCD in my house never gets checked either, unless im doing something and short N-E

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but the problem being, in real life, RCD's should be tested regularly. which should avoid the problem of sticking. but people don't do this, so it may not operate when needed. what we need is an RCD that works like an MCB, in that it doesn't need tested (or open/closed) often

Who says mcb don't fail the only reason we know rcd fail because we can test them with meters and a test button, how do we test mcb's we don't we just hope they work

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i dont think DNO would be happy with us testing MCB's!

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i dont think DNO would be happy with us testing MCB's!

I will just apply my 50amp short circuit tester cable across the shower circuit....

Boom, flash, spark!!!! :o:D:^O:^O:^O:^O

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I will just apply my 50amp short circuit tester cable across the shower circuit....

Boom, flash, spark!!!! :o:D:^O:^O:^O:^O

ill just add to that.....

Boom, flash, spark!!!! Blackout!!!

well, not always, been on a job before when drilling through the feed didnt blow 300A fuse, and neither did cutting through it live (stupid DNO bloke! i told him it was live, but no, he knows best!)

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Dont agree with that one NOZ ! Sometimes these RCDs have not been operated for years and after a couple of trip tests they are back to spec.

if people tested them Quarterly ,as recommended, then it wouldnt be a problem,in practice this doesnt happen ,but following the trip testing its back within spec as the test meter results verify .

:D

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I do not like the fact that a RCD that is used as additional protection "may" fail simply because the reccomended testing intervals are not adhered to.

I have rcd's in my home been there for about 10 years now, tested? NEVER. and I am an electrician. If you work from home I suppose your monthly checks for calibration would test the rcd's, but if you work from an office or unit then the tests are carried out there.

People will not carry out the checks, often although the information is provided they will forget, or simply not bother, there is then a risk that under a fault the rcd will NOT operate within the required time.

If this where to happen, and god forbid a fatality occured, who would be to blame?

Unfortunately it would be the owner, because the manufacturer of the rcd will undoubtedly say, because the required testing was not carried out, failure is down to the owners.

I think this is shamefull.

The requirement for rcd protection is mainly about giving a greater degree of protection to the work done by incompetent sparks (many of whom have passed many yearly assessments) and the public themselves. Since the inception of the 17th Ed, even householders must ensure that rcd`s are fitted as, and when, appropriate - but they can`t test them so how can they comply with BS7671?

The idea of full rcd protection by way of consumer unit upgrades is a back-door method of reducing the risk of the wholesale bodging that the government will never admit actually takes place. The fact that this is steadily pushing more and more work into the hands of the very people it was meant to stop is considering incidental - our dwindling business is deemed collateral damage of little consequence............

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  • 2 weeks later...
All I will say is that you only get one chance for the RCD to trip in the event of a fault!!

IMO.... if it doesn't trip the first time (within limits) then it's a fail

:coat

Absolutely 200% agree with you Noz.

How about this: you've got a ten year old car. You have an accident. The airbags fail to operate within spec and someone is injured. Oh, but that's okay 'cos they haven't been tested for ten years.

i don't think so!! Big litigation ahead.

The quarterly test is only a recommendation, not a get out clause for a faulty item (although I'd say about 50% of RCD failures are due to dust and dirt, usually plaster dust, getting inside them and gumming them up - a very good reson to ensure the necessary IP protection for top surfaces of CUs)

Safety first.

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If you know that the rcd is failing due to mechanical problems that can easily be rectified, i.e by switching it on and off a few times, and insist on replacing the item with a similar rcd that is prone to exactly the same problems you could very likely be found guilty of deception and taking money under false pretences. As long as the rcd functions within accepted parameters under standard test conditions before you leave, you cannot be held responsible for the customer failing to follow the manufacturers guidelines.

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i would not replace a RCD that once i have finished testing it is working fine. If the item is used outside the manufactures recommendation its no suprise its not working, if you just stick another one in a couple of years down the line same problem, surely education of the end user is the best thing here!

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