Morning.

markc123 · May 15, 2015

Morning Men, Women & Mike...

Just a quick one, and i realise im going to sound completley stupid here ...

I've been called to a static caravan 3 times in the last week - the last time being monday morning. There had been no power to the caravan, although no breakers tripped out either in the distribution board outside or the consumer unit inside. I asked neighbours and the park owners whether they had been having power cuts recently and nope - it's just this one caravan. This too me suggests a loose connection somewhere, the first time i went i did a thorough test of the install with all readings more than acceptable - i also checked for loose connections on the incomer - literally couldn't find a thing. Second time i went, i literally repeated myself and again nothing - it doesn't help with the fact everytime i got to the static the power had come back on...

Anyway the third time on monday, i just replaced the RCD - even though the old RCD tripped out in accordance with regs at 1/2 1 and 5 on both cycles and the test button worked ... no idea why i replaced the RCD, but i was kind of struggling. Anyway since then there hasn't been a problem...

So my newbie question is : Can RCD'S actually go faulty even though they test and trip out at the required times?

(I've come across RCD's and MCB's that don't pass the juice across before, but everytime i was there this one was working exactly as it should be.)

ruston · May 15, 2015

My first thoughts are the customer must of been resetting the RCD.

Marvo · May 15, 2015

It's very unlikely to be the RCD unless it was actually physically tripping, it would be better odds on an intermittent leakage problem and someone resetting it without the knowledge of the person you spoke to. That said anythings possible so maybe soak test the RCD on a known-good installation for a week or so or I guess with the low price of them nowadays it's probably not worth it so just dump it as suspect if the problem in the caravan doesn't reoccur.

Richard Burns · May 15, 2015

I would think that perhaps there was a strand of conductive dust or cable that was causing the fault (perhaps even an intermittent loose connection generating enough spiking to cause the RCD to trip) that has been removed by your actions.
It could also be that the RCD was tripping at 16mA and there is an intermittent fault to say 20mA and your new RCD is tripping at 27mA or figures to that effect.

The most likely cause is the user realised the power tripped out every time they used the kettle and have now replaced the kettle without telling you.:smile5:

ruston · May 15, 2015

Marvo said:
It's very unlikely to be the RCD unless it was actually physically tripping, it would be better odds on an intermittent leakage problem and someone resetting it without the knowledge of the person you spoke to. That said anythings possible so maybe soak test the RCD on a known-good installation for a week or so or I guess with the low price of them nowadays it's probably not worth it so just dump it as suspect if the problem in the caravan doesn't reoccur.

I couldn't help myself lol, I would have to find out.