Resetting RCD

[Bodgitt]

I have power and light to my shed which has been there 6 years with no problems, suddenly it starts tripping and I'm unable to reset it. I have unplugged everything from it still it wont reset, I've checked the fuses all ok. power gets through for an instant before tripping. Could the switch itself have failed?

 

[Veglen]

What’s tripping, MCB or RCD?

Could it be water ingress in one of the accessories?

V

Edited to say - Sorry just noticed the title

 

[davy_owen_88]

As the device is tripping even after everything has been unplugged, that indicates a fault on the cables. The first option if you feel confident to do so, would be to remove all the socket/switch fronts and check for any loose connections - I know you said the device is tripping but before you do carry out the work ensure that the power is off (not using a neon-screwdriver).

To help us narrow down the possible cause of problems:

Are you defininately talking about an RCD - a device taking up 2 ways on your consumer unit and with a 'TEST' button on the front?
Have you nailed/screwed anything to the walls/ceiling/floor?
Been digging over the garden and found that you've hit something hard and cable shaped?
Has the weather been as crap as it has been here? I.e lots of rain?
Have you done any DIY electrics lately?

 

[Bodgitt]

yes
no
no
yes
no

I've managed to reset it now but it did make a sort of vibration noise(?) at first
Trouble is, The underlying problem, isn't sorted

 

[Taylortwocities]

Then you will need a calibrated insulation test meter and an RCD tester and someone who knows how to drive these.

This then will detremine if there's a problem with the wiring or if the RCD is dodgy (I am told that around 7% of RCDs are subject to failure during their brief but spectacular lives).

 

[Bodgitt]

Thanks all for your help, I think I'll have to collar a passing electrician to check it out.
Cheers

 

[BS3036]

I know I won't get thanked for saying this but this 7% rumour has been spread for so long... Someone on here quoted a news item which led to the original report which used some out of date Italian figures to induce people to read their report which then concluded that there was 'a failure rate of 2.8%, ALL of which would have been detected by operating the test button. '

Just thought I'd mention it.

 

[RF Lighting]

Out of interest, how many pro's on here regularly come across failed RCDs, or RCDs operating outside of there design characteristics?

I'm just curious, as 7%, or 7 in every 100 seems quite high.

That's nearly one in every 10 RCDs which do not work.

 

[ricicle]

Out of interest, how many pro's on here regularly come across failed RCDs, or RCDs operating outside of there design characteristics?

I'm just curious, as 7%, or 7 in every 100 seems quite high.

That's nearly one in every 10 RCDs which do not work.

Never - just the occasional test button failure.

 

[Spark123]

Had 6 fail at the theatre over a period of a few years:
Two tripped on 0.5I.
Three didn't trip when you pressed the test button (one was a faulty button which I managed to repair), one I just binned as was old, one was a newish Square D RCBO which I took to bits just to see what was in it!
The sixth one was a victim of someone failing to tighten the screws properly.

 

[plugwash]

I have heared that RCD reliability depends heavilly on the conditions. Indoors in a house they are very reliable but put them in an enclosure outside (say a caravan site hookup unit) and the reliability goes through the floor. One story I heared was someone found all the RCDs on a caravan park seized, replaced them all and when the time for the next PIR came round the replacements had suffered the same fate.

Apparently though the RCDs started working again after being cycled once, another good reason to use the test button!