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Failure rate of RCDs #193924
04/28/10 06:42 PM
04/28/10 06:42 PM
C-H  Offline OP
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
The Danish authorities have undertaken a large study of the realibility of RCDs in which hundreds of installations have been tested. From 2 to 10% of the units were found not to work as intended. Some passed the test button test, but failed to work when tested with proper equipment test. The failure rate was found to increase with age and brand name products were not immune to failure.

A comprehensive report in English is available at:

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Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Large Selection of Test Equipment For Electrical, HVAC, Test & Measurement
Re: Failure rate of RCDs [Re: C-H] #193925
04/28/10 07:06 PM
04/28/10 07:06 PM
Wolfgang  Offline
Joined: Sep 2005
Posts: 153
the very West of Germany
The main problem, I see, is not a failure rate of 10% after 10 years, because we can easily check these devices (as electricians), but what about fuses or breakers. There are so many out there, aged 30 or 40 years, but nobody can tell whether they will trip at the correct overcurrent value after such a long time.

Re: Failure rate of RCDs [Re: Wolfgang] #193936
04/29/10 10:05 AM
04/29/10 10:05 AM
Texas_Ranger  Offline
Joined: Dec 2001
Posts: 2,416
Vienna, Austria
I haven't seen to many failed RCDs so far, and most failed on the safe side - tripped and couldn't be reset any more. Only one or two refused to trip, on one even the test resistor blew up spectacularly.

Same goes for MCBs, but I did encounter one very old range (Schrack HLS, manufacturing date stamp 1960) that refused to trip as a whole. There were a few dead shorts (faulty light socket) but the MCBs (10A H curve) never tripped before the 20A gL main fuse blew.

Re: Failure rate of RCDs [Re: Texas_Ranger] #193941
04/30/10 02:20 AM
04/30/10 02:20 AM
frenchelectrican  Offline
Joined: Feb 2003
Posts: 939
Wi/ Paris France { France for ...
I haven't run into too many RCD failure in France unless you got a Le Cheapie or butched work on the RCD unit.

Yeah we do test the RCD but with older units it pretty tricky to get set up to function properly.

But with nice hevey bolted fault circuit then it is good time to replace the RCD I have deal with that due once you reset it it will never function correct.


Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


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