DIY Doctor UK DIY Forums

Hi can any one help me.i have a fuse board with a rcd in it and last night the socket was arcing badly (glowing orange) then the mcb breaker tripped a few seconds later.but the rcd stayed on and nothing was plugged in to the socket.why wouldn't the rcd trip as its suppose to be a safety trip.it's a 30 m/a 80 amp and its only 8 months old ? any ideas would be great (for now i have left it switched off)

Hi,
The problem was obviously a Live to Neutral fault leading to an overload current flowing which was quite correctly stopped by the Min. circuit breaker designed for that purpose .
The RCD should not trip unless there is a Live to earth fault when a current of more than 30mA would trip it.
It doesn't matter how much current flows L-N the RCD won't trip, even way over it's 80A rating which is only it's safe breaking capacity,
It has no ability to detect L-N faults which is why you have both MCB's & RCD's,
regards SPARX

Hi sparx thanks for your reply ..I Have removed socket and found that the screw that holds the socket back to the box has been caught on the brown wire which is now melted away.Electrician coming out on saturday.