Who trusts RCDs?

Piratepete · Mar 18, 2012

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

KFH · Mar 19, 2012

For what it is worth my thoughts are:

Test at 5* before 1/2* and 1* if it fails it has failed. I tell the customer it has failed, if subsequent tests are OK it has still failed. If the customer has not been pressing the test button occasionally why are they going to change? If there is no replacement available and the board needs replacement that is their decision not mine. I am pretty sure if someone dies after I have said "its OK I had to exercise it a few times to get it to work" it is me who is going to be to blame. If it has stuck once there is a good chance it will again.

GLENNSPARK · Mar 19, 2012

wirepuller said:
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.

well the 32A wylex RCBO i refered to at #51 certainly didn`t trip when subjected to test....at 1x...and 5x......further more...had a job recently where the RCD on a split load 5+5 kept letting go....disconnected all loads and ramped it.....couldn`t even get a reading on it....it went that quick......binned it and replaced with new.....that was a wylex n all......

Deleted member 9648 · Mar 19, 2012

GLENNSPARK said:
well the 32A wylex RCBO i refered to at #51 certainly didn`t trip when subjected to test....at 1x...and 5x......further more...had a job recently where the RCD on a split load 5+5 kept letting go....disconnected all loads and ramped it.....couldn`t even get a reading on it....it went that quick......binned it and replaced with new.....that was a wylex n all......

Not doubting you or anyone else....maybe I've just been lucky....but can hand on heart I can say that what I posted has been my experience with RCD's.