Who trusts RCDs?

[Piratepete]

Hi Guys
Did a small job in a house - one additional socket. Then did an RCD test - x1 (240 mSec) and x5 failed miserably. did the test a couple more times. Some improvement but still failed. The RCD is an old Wylex WSES 80/2 so replacement means a new CU. Customer asked me to test it again - it passed and continued to do so! Stabilised at 106/10 mS. Asked him when he last pressed the Test button - 6 years ago!

I assume that it just got sticky from lack of use! Does this happen to modern RCDs? I must admit that though this is the first that I've tested which failed about 5 operations I've tested many which initially give high readings (though not failed) first time around.
It seems a bit crap if whether you die or not all depends on whether the householder has pressed the test button in the last 6 months!:icon13:
Pete

 

[Marvo]

Rcbo's have overload. Haven't seen any Rcd's with overload.

Most of these RCD's (RCBO's) are available with overload protection, rcd protection and they're rated as an isolator.

CBI-electric: Australia Pty Ltd -- Products: Commercial and Industrial RCBO's and RCCB's

 

[rich.250]

Rccb's, rcbo's and Rcd's are not the same thing. Yes they do a similar job. But as you said some have overload. As where a standard Rcd does not.

 

[Piratepete]

Hi Pete,

Here's a link to an updated conclusion from the research: RCDs pass the test of time

OK. I've read the full report. Table 3 : Effect of using Test Button on failure rate - provides the interesting info. Of 298 rcds that hadn't been tested for more than 5 years only 8 failed = 2.7%
Overall failure rate (607 tested) = 2.8%

That's 28 in a 1000. Apparently this is acceptable!

But 8 failed out of 181 which had unknown test dates- this is 4.4 %

I quote from the report:
'It is likely that operating the RCD test button does improve the reliability of the RCD, but the result is not clear cut for the RCDs tested by ERA because the Housing Authorities (used for the research) do not keep good records of test dates and RCD ages.'
A sticktion test was also done where the RCD was tested 3 times and the values compared. ERA found no evidence of sticking but it is not clear from the report as only total average figures are shown (in table 4). If I interpret the report correctly this test was carried out on 435 RCDs. I would like to have seen the results for the 298 RCDs that weren't tested for more than 5 years.
There are other notes relating to the statistical unreliability of the results.

Methinks that the jury is still out and that somehow a larger sample of RCDs of known age and test history needs analysis to prove long term reliability with no sticktion. You're never going to persuade Joe Public to regularly press the Test button.
Pete

 

[La Poste]

I had 4 new out of 15 that didn't work......
Shall I disclose the manufacturer?? LOL

Yes please I would love to know the manufacturer.

 

[rich.250]

Sector. Rexel senate own brand. Aparently made by wylex.

 

[GLENNSPARK]

we had it the other week.....wylex 32A RCBO....dead straight out of the box.....

 

[rich.250]

I was wondering if it's the rough delivery service..... Lol

 

[La Poste]

Anyone seen many MK failures?

 

[rich.250]

I fit mainly Mk and haven't had one.

 

[La Poste]

How many MK's in this report?

Does the report mention brand names?

 

[GLENNSPARK]

was at a house last week....protius C/U.....one of the worst piles of doo doo i have ever had to work on....left thinking the best place for it was in the bin......

 

[trev]

Got to agree with Glenn on this, Proteus gear is bloody awful.
I've had a few MK failures in my time but no more or less than any other brand, it's usually decent kit to work with though.

 

[SPARTYKUS]

If I knew more maths Id get the joke.


J integer is in there somewhere.?

Complex nos ...never got them first time round

Square root of -1 ? Whaas dhat all aboot then

 

[Engineer54]

Commenting on a report that you haven't even read! If I'm 'trying to be clever', you're making it easy for me by posting this sort of rubbish!

Summary
This report contains a review and analysis of the results of tests conducted on RCDs
installed in domestic properties to determine if they would operate in the specified time when
tested at 30mA and/or 150mA. 607 electromechanical RCDs were tested in properties in
the UK owned by Housing Associations and Local Authorities.

I guess it's just those statistics again! Plonker!

Oh let me assure you IQ, I'm nobodies fool!! And contrary to your suggestion, I ''Have'' read this ERA report and in it's entirety, not just a summary that you seem to have read. It was however a good 2 or 3 years ago, but still remember the amount of holes and controversy that surrounded it, if not all of the fine details...

Your right this version of the report IS just a review/summary, the version i read was the Full report, and with comments from contractors, most of whom, were stating that this report didn't reflect there experiences (Surprise Surprise!!). There was also one of the electricians, that was involved in the testing for this report, (so no they didn't conduct the tests themselves) who refutes that the full stated number of RCDs were actually tested. Also as i remember it, these housing associations were located in and around middle England and NOT over the whole UK as this summary implies.

The report that i read looked as if it had come from an official website were the comments were made. i've tried looking at the ERA and ESC sites but can't locate it, or even the the full version of this report, which is strange to say the least!! To be honest, i'm a little surprised you don't have a copy, seeing as your always telling me that your surrounded by all these publications reports and what have you....

I don't think i need to go on, as virtually everyone here that's posted, can probably give a series of known failures, whether straight out of the box, or in place units, as i'm sure even you can. I would even hazard a wild guess here, that no-one can say that the overall reliability that they have found, approaches anywhere near 97%!! And i can whole heartily confirm that, from my own pretty extensive experience with RCD failure rates... I'm not saying that i don't have some degree of trust in RCD devices, because i most certainly do, but don't look on them as the cure all Saviour device either and i'm more than aware that they are not as reliable as the manufacturers (and others) would have you believe....

Your the guy that loves to take notice of ''Statistics'' and it seems, to believe every word (or should i say figure) that's presented to you. I prefer to stand by what i know, ...first hand if you like!! If that makes me a Plonker then that's totally fine by me!! lol!!!

 

[Deleted member 9648]

Oh let me assure you IQ, I'm nobodies fool!! And contrary to your suggestion, I ''Have'' read this ERA report and in it's entirety, not just a summary that you seem to have read. It was however a good 2 or 3 years ago, but still remember the amount of holes and controversy that surrounded it, if not all of the fine details...

Your right this version of the report IS just a review/summary, the version i read was the Full report, and with comments from contractors, most of whom, were stating that this report didn't reflect there experiences (Surprise Surprise!!). There was also one of the electricians, that was involved in the testing for this report, (so no they didn't conduct the tests themselves) who refutes that the full stated number of RCDs were actually tested. Also as i remember it, these housing associations were located in and around middle England and NOT over the whole UK as this summary implies.

The report that i read looked as if it had come from an official website were the comments were made. i've tried looking at the ERA and ESC sites but can't locate it, or even the the full version of this report, which is strange to say the least!! To be honest, i'm a little surprised you don't have a copy, seeing as your always telling me that your surrounded by all these publications reports and what have you....

I don't think i need to go on, as virtually everyone here that's posted, can probably give a series of known failures, whether straight out of the box, or in place units, as i'm sure even you can. I would even hazard a wild guess here, that no-one can say that the overall reliability that they have found, approaches anywhere near 97%!! And i can whole heartily confirm that, from my own pretty extensive experience with RCD failure rates... I'm not saying that i don't have some degree of trust in RCD devices, because i most certainly do, but don't look on them as the cure all Saviour device either and i'm more than aware that they are not as reliable as the manufacturers (and others) would have you believe....

Your the guy that loves to take notice of ''Statistics'' and it seems, to believe every word (or should i say figure) that's presented to you. I prefer to stand by what i know, ...first hand if you like!! If that makes me a Plonker then that's totally fine by me!! lol!!!

Just trawled through this entire thread and can honestly state this is my experience of RCD's....based on fitting and testing hundreds in recent years.

1. Cant remember ever having a unit of any make fail to operate in the required time....if it has it has always been because of connected loads.
2. Failures straight out of the box have always been failure to reset after tripping...(either with the button or tester)...not failure to trip.I can think of only think of a couple of instances.
3. I have on occasion come across 'sticky' units...always older wylex units...never more recent electronic units.

While that may be at odds with the experience of other members on here it has been my experience,and based on that I believe RCD's are no less reliable than any other electical equipment.