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

 

[IQ Electrical]

Look a little deeper on how the ESC/ERA operates and who finances them....

So what are you saying, ...that this ERA report ultimately proves that RCD's are as reliable as MCB's/MCCB's??

No! I'm saying that a report was done and the findings presented!
We have no such report on MCBs/MCCBs so I can't make that statement but I doubt if failure rates would be massively far apart.

The ESC is run by a board that spans the electrical industry from NICEIC to ECA and many in between, it provides excellent information to us as contractors/specifiers/end users-how many times is an ESC publication linked to from this forum?

The report was carried out by ERA so what does the ESC funding structure have to do with the ERA report's integrity? Sheesh, some people just won't be told even when presented with the research!

Or, maybe it was all a fix-the ERA report was nobbled by NICEIC just like the 'man on the moon' conspiracy, only contentious point being 'why?'
I'll leave that one with you......

http://www.esc.org.uk/stakeholder/about-us/our-board/

 

[yellowvanman]

Generally there is 'no smoke without fire'. If an RCD doesn't operate to spec the first time maybe next time its asked to operate someone could get killed if it doesn't operate to spec.

I don't know the insides of an RCD specifically but there must be some sort of containation to cause the contacts to stick - once contacts are contaminated doesn't take long for it to build up again.

On another point I always tell my customers to check the RCDs when they have to change the clocks, that gives an opportunity 2 times a year. Whether they do or not is another matter.

 

[mhar]

What a simple good idea yellowvan man, the clocks that is

 

[Piratepete]

Thanks guys for all your replies. Makes interesting reading and a conundrum. The RCD in question hadn't been tested for 6 years. The CU is in a dry clean location.
I've not read the ERA report. How many RCDs did they test that hadn't been tripped for years?
I also don't know the design criteria. Do the manufacturers say that if it is NOT manually tripped every 6 months then they can't guarantee it will trip under fault conditions? Anybody know?
Pete

 

[IQ Electrical]

Thanks guys for all your replies. Makes interesting reading and a conundrum. The RCD in question hadn't been tested for 6 years. The CU is in a dry clean location.
I've not read the ERA report. How many RCDs did they test that hadn't been tripped for years?
I also don't know the design criteria. Do the manufacturers say that if it is NOT manually tripped every 6 months then they can't guarantee it will trip under fault conditions? Anybody know?
Pete

Hi Pete,

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

 

[SPARTYKUS]

Maybe theres a case for a new CU- one with dual-dual RCDs!! Would cover a single failure! And no problem with them in series as theyd be 10 microns apart

 

[Engineer54]

No! I'm saying that a report was done and the findings presented!
We have no such report on MCBs/MCCBs so I can't make that statement but I doubt if failure rates would be massively far apart.

Really!!! I don't have any idea how you could possibly come to that conclusion?? Perhaps you see too few RCD failures, i don't know!! But most of the RCD's you will see, you'll probably only see once or maybe, on the outside twice. Whereas the RCD devices on my projects will be generally monitored for a minimum of 2 years and some even longer, ...and were talking here in the thousands, not the one or two hundred your likely to see over a year!!!! I can categorically tell you as a ''Fact'', that RCD devices are not at this time, anywhere near as reliable as you or this report makes them out to be...

The ESC is run by a board that spans the electrical industry from NICEIC to ECA and many in between, it provides excellent information to us as contractors/specifiers/end users-how many times is an ESC publication linked to from this forum?

I'm not saying they don't provide some good information in the general sphere of things...

Or, maybe it was all a fix-the ERA report was nobbled by NICEIC just like the 'man on the moon' conspiracy, only contentious point being 'why?'
I'll leave that one with you......

LOL, ....Who said anything about being knobbled?? This is just normal business/marketing practice, the sort of thing that manufacturers are always looking for!! Your still trying to be clever, raising a naff report, and using that, to base the reliability of RCD's as being on par with MCB's, ....Yeah right!!

Unlike you, i'm not naive enough to take anything/everything that's published as gospel/fact, especially when it's in a report form, that is based on those dammed ''Statistics'' ... I suppose you believe the published government reports too, well before they are torn apart by the opposition and the media...lol!!! That ERA report on RCD's was to say the least a bit of a farce. How many actual RCD units did this report research team actually test, i know it wasn't 607?? As i remember, they only tested a relatively tiny number of removed RCD's, that were removed during electrical call outs from some housing association. The report wasn't based on the testing of all the RCD's installed on these 607 installations. Who knows how many of those are faulty, at the very least, that would have made more sense to base a report on, and not on the few RCD's that were removed as being faulty!!

Come to that, why not post that ERA report here, so that everyone else can see just how many RCD's this report was based on??

 

[Guest111]

probably the reason joe public do not test rcd,s monthly has more to do with kids than clocks,even shutting down power for a minute brings wails which appear to indicate an impending apocalypse,shut down the juice and the kids think the end really is nigh. Dont know what they would do if the power cuts we had in the 70,s came back

 

[Engineer54]

Hi Pete,

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

Where's the full Report .... this is skirting over just about everything!!!

 

[IQ Electrical]

Really!!! I don't have any idea how you could possibly come to that conclusion?? Perhaps you see too few RCD failures, i don't know!! But most of the RCD's you will see, you'll probably only see once or maybe, on the outside twice. Whereas the RCD devices on my projects will be generally monitored for a minimum of 2 years and some even longer, ...and were talking here in the thousands, not the one or two hundred your likely to see over a year!!!! I can categorically tell you as a ''Fact'', that RCD devices are not at this time, anywhere near as reliable as you or this report makes them out to be...



I'm not saying they don't provide some good information in the general sphere of things...



LOL, ....Who said anything about being knobbled?? This is just normal business/marketing practice, the sort of thing that manufacturers are always looking for!! Your still trying to be clever, raising a naff report, and using that, to base the reliability of RCD's as being on par with MCB's, ....Yeah right!!

Unlike you, i'm not naive enough to take anything/everything that's published as gospel/fact, especially when it's in a report form, that is based on those dammed ''Statistics'' ... I suppose you believe the published government reports too, well before they are torn apart by the opposition and the media...lol!!! That ERA report on RCD's was to say the least a bit of a farce. How many actual RCD units did this report research team actually test, i know it wasn't 607?? As i remember, they only tested a relatively tiny number of removed RCD's, that were removed during electrical call outs from some housing association. The report wasn't based on the testing of all the RCD's installed on these 607 installations. Who knows how many of those are faulty, at the very least, that would have made more sense to base a report on, and not on the few RCD's that were removed as being faulty!!

Come to that, why not post that ERA report here, so that everyone else can see just how many RCD's this report was based on??

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!

 

[Marvo]

Please keep discussions civil.

 

[rich.250]

Generally there is 'no smoke without fire'. If an RCD doesn't operate to spec the first time maybe next time its asked to operate someone could get killed if it doesn't operate to spec.

I don't know the insides of an RCD specifically but there must be some sort of containation to cause the contacts to stick - once contacts are contaminated doesn't take long for it to build up again.

On another point I always tell my customers to check the RCDs when they have to change the clocks, that gives an opportunity 2 times a year. Whether they do or not is another matter.

Good plan,
from experience they stick cos the majority are overloaded.
Especially with manufacturers pushing dual 63a Rcd units.
Let's not start there lol.

People don't seem to realise that Rcd's have no protection for overload and the contacts are only rated to rating on them.....

 

[GLENNSPARK]

probably the reason joe public do not test rcd,s monthly has more to do with kids than clocks,even shutting down power for a minute brings wails which appear to indicate an impending apocalypse,shut down the juice and the kids think the end really is nigh. Dont know what they would do if the power cuts we had in the 70,s came back

no phil....its ignorance mate....joe public cant understand/doesn`t care about RCDs, how they work.....and what causes them to fail.....

 

[Marvo]

People don't seem to realise that Rcd's have no protection for overload and the contacts are only rated to rating on them.....

Some do incorporate overload protection, some don't, it depends on the spec of the particular RCD.

 

[rich.250]

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