Rcd failure

[terry1969]

Went to a job this morn rcd trips in kitchen , went to have a look pat tested some items and IR on dishwasher was 0.47 ohms , so must be the issue everything else was ok , tested rcd on kitchen ring and rcd didn’t trip , so tested the rcd at the board mk 7800 series and it tripped but not in the times x5 <300 x1 40ms so the rcd is at fault ? , sounds a silly question but not done much fault finding . Ready for the abuse

 

[cliffed]

Looks like Rcd faulty,peculiar both not working.
Try with all mcbs off,then do tests.

 

[terry1969]

Yeah was all off mate

 

[plugsandsparks]

disconnect outgoing connections to rcd and test again, only way to be sure.
cheers
P&S

 

[Andy78]

RCD tested with all outgoing neutrals disconnected ?
I've had it before where n-e faults prevent proper RCD function under test.

In my experience it's never a faulty rcd

 

[plugsandsparks]

I have had one in my lifetime, was doing an EICR and it blew up in my face when i pressed the test button... (there was evidence of water damage so i cannot blame poor quality)

 

[richy3333]

I have had one in my lifetime, was doing an EICR and it blew up in my face when i pressed the test button... (there was evidence of water damage so i cannot blame poor quality)

Crikey that’s one pant filling episode!

 

[HappyHippyDad]

I agree with Andy. I have only had 1 faulty RCD that has been the cause of a non tripping RCD, it was a Chint.

I had a very bad N-E fault the other day and this was stopping the RCD from tripping when tested at a socket or indeed when tested anywhere in the house. When I disconnected the RCD from all circuits it tested absolutely fine (thanks again DS) and the problem was a screw through a cable causing continuity between N-E.

So that would be my advice. Disconnect all outgoing circuits from that RCD so the RCD can be tested without any influence from the circuits. This will at least eliminate the RCD from being faulty (unless of course it is).

 

[Dustydazzler]

I have had one in my lifetime, was doing an EICR and it blew up in my face when i pressed the test button... (there was evidence of water damage so i cannot blame poor quality)

Have had 2 old RCD's physically blow up when the test button was depressed...

On both occasions just a big bang/flash and the toggle just went floppy like limp spaghetti

Have also had older MCBs when tripped off won't turn back on

 

[plugsandsparks]

Crikey that’s one pant filling episode!

Forgot to mention was on a step ladder as well, funny how you remember stuff like this..

 

[shaun1]

I found a BG RCD in my brothers house that wouldnt trip under test. Switched it on and off a few times and it tripped at a much higher current. After a lot of turning on and off to free it up I got it down to about 50mA on ramp and about 60mS on 5x current I think. So I guess it had siezed somehow.

 

[MJPD29]

I found a BG RCD in my brothers house that wouldnt trip under test. Switched it on and off a few times and it tripped at a much higher current. After a lot of turning on and off to free it up I got it down to about 50mA on ramp and about 60mS on 5x current I think. So I guess it had siezed somehow.

I had this with 3 separate brand new rcds on BG boards. That's why I have no trust in them the are poor quality

 

[telectrix]

and i've fitted loads of them and not had any failures. thought i had one once, but it was a N-E fault on a socket radial.

 

[Deleted account]

Had 3 rcd failures.

2 on one split board I had installed. Test button didn’t work on one six months later. Replaced it.
Six months later test button failed on other one.
Later found out was a faulty batch.

I’m amazed a customer actually took notice of my instructions to test rcd quarterly.
Don’t normally fit split boards but it was a flat with 4 circuits, so saved customer a bit of dosh.

Third failure was an overloaded Rcd rated at 60A it had most of property ri through it including shower, oven, hob.

 

[Barney(UK)]

I had this with 3 separate brand new rcds on BG boards. That's why I have no trust in them the are poor quality

BG do seem problematic, I had ten of their new style RCBO’s failing tests on a new consumer unit install last week.
Yesterday I did a minor job for someone and tested their two split BG RCD’s and whilst one passed the other one failed all the tests and even the test button wouldn’t operate it. I purchased a new BG RCD and just fitted it and it failed the 1x 30ma test >300ms on one side of the wave, tried again with everything else disconnected and same result! Will be getting onto BG in a minute about this one.
Oh before anyone says it, my meter is calibrated, regularly tested with a known source and I have tested other RCDs between these jobs with satisfactory results ?