rcd tripping

colshaws · Oct 21, 2012

Hi all.
Need some help,I fitted a new dual rcd board today and have problems with the RFC tripping the RCD. Test results for circuit are as follows, r1=.34, rn=.36, r2= .81 (r2 a little higher than expected but I think still o.k?) I.R= 10.6 M ohms.lower than I would like but still acceptable ( again I think?)
Connect circuit and energise and all is ok, start switching on appliances and RCD trips,I tried all appliances off and switching on one at a time hoping to find the fault but any combination can make it happen especially ones drawing a higher load.ie kettle or microwave. Disconnected all other circuits to eliminate borrowed or wrongly placed neutral, tried circuit on the other RCD but still trips. Any suggestions on the best way forward

Liam12 · Oct 21, 2012

I reckon it's that welder in the shed ;-)

Clive P · Oct 22, 2012

I posted a reply similar to this problem sometime ago. I would go with Spark 68 on this one. I had a similar problem, where you could turn the lights on, but as soon as you plugged in an appliance the Board RCD tripped. The fault was that the internal 'tails' within the CU had been connected incorrectly. Worth a check,

Regards.

murdy2k5 · Oct 22, 2012

colshaws said:
EFLI tested at 1 socket tripped RCD, but was ok at another,this socket also gave me a higher R1+R2 than others but was fine at terminals on back of socket so I changed the socket but didnt check ZS at this socket afterwards, by this time by head was begining to hurt.

as the other guys are saying the RCD checks what is going in thro the phase and back via the neutral. if you are not getting the same in and out the tordiol inside the RCD senses an imbalance and trips. check that all the neutrals and earths are in the correct place. if you have any transformers in any of the circuits check that they are not faulty. as the neutrals and earths end up at the same place it has got to be on the return/neutral side that you have a fault other wise you would have a dead short.

good luck finding your needle in a haystack!