Possible cause for a RCD to die?

[Gavin John Hyde]

On a job today to add a couple of outdoor security lights.

House is currently empty and has been for a couple months due to probate and its about to have a little bit of work done before going on market.

The power was off when i got there, turned it on and the RCD is completely dead... it has failed, with power going through the switch wont hold its position. Power goes to it but nothing comes through out to the MCBS. I took it out and tried in my CU in at home and same result.

I know RCD's can seize up if not operated for a long time but this is a first for me. I have never actually come across a RCD that seemingly has 100% stopped working and is dead.

I did wonder about temperature, moisture etc.. but its not that bad in there. no damp or mould ....

There is nothing plugged in to any of the circuits on this side of board. and house is otherwise empty. i tried the turning off mcbs and methodically turning on etc and rcd is still dead.

The RCD was working when i went round on 2/8/17 as i met the daughter who is dealing with the estate and the power was all on and working fine. The other RCD on board is working fine

A bit baffled as the power was turned off when we left and nobody had been back in since...

Any ideas on causes or what might have happened to RCD to just die like this?

If it helps its a BG (British General) 63A 30mA RCD.. nothing too fancy

 

[static zap]

Look for clues , is it really spottless . Plaster dust , spider cobwebs .
Any bare metal to show up corrosive fumes ?
---------------
I suggest a postmortem of RCD if interested ! --start with a sniff--
Guessing posibles ...
a) signs of flashover / arc ...(old damage) Nasty Earth - neutral event ..TT ?
b) insect invaision
c) broken parts..if you can tell !
d) corrosion
e) old age
f) Hexed by local coven ...
( appologies - imagination ...)

 

[Gavin John Hyde]

Only thing i can think of is damage to the incoming terminals as there is a very very fine crack barely noticeable to naked eye where screws are. Only saw it when i wrote on it with a red marker as ink went into crack.. Maybe something loose and shorting?? Guess we will never know.....

 

[telectrix]

take it to bits.

 

[Wilko]

And post pics

 

[telectrix]

And post pics

in a jiffy bag.

 

[Gavin John Hyde]

If and when I go back to fit a replacement ill try to remember to keep it and take apart, not sure what i hope to find though! at the moment i have fitted one busbar for all circuits on the remaining RCD. To be continued....

 

[static zap]

Did find a ref on Poofix ... Tighen screws with care -as easy to crack case ...
(Does that put them in the budget catagory ?)

 

[NDG Elecs]

Don't use BG RCDs is my two penneth! I have had around 4 separate issues with their RCDs alone. I have never had one that is dead on the outgoing side, but have had incorrect trip times and bad ramp results, not to mention the carp cage clamps.

When you go to replace it I would take two new RCDs just in case one of the new ones is not right.

I wouldn't mind so much but they are not half the price of a decent Hager board. For the poor quality that they are, they should be half the cost maximum!