Not really. It's a matter of testing all N-E in the CU to find out which ring is causing trouble (if it is an N-E). Mine was the kitchen ring, yours may be a different ring.
If you don't mind me saying so, your question bothers me a little. It suggests that you may not be safe in doing this. eg, You may not put things back properly safe.
Think about calling in a leckie maybe?
I have replaced everything as it was before... however I agree entirely with you in that it's time to call in someone who knows what he's doing, I have a degree in electronic engineering which means I'm happy with all volages between 0 and 5 :-)
A recommended leckie is heading round this afternoon to try and see where the problem is.
As an aside can anyone hazard a guess about how much I should expect to pay for someone to install a replacement split-load CU?
Cheers,
Ben
So we had a competent (I believe) electrician round, got out his megger, tested the kitchen sockets circuit L-E and N-E and found no low resistances at all. Having found nothing he then tested all the other circuits and again found nothing.
(Bear in mind that the RCD only tripped, every 4-8 hours, when the kitchen sockets were on)
He then tested the RCD and found that it was tripping at 20mA not 30mA (although from comments I've seen in this forum I think I'm right in saying that an 'in-spec' 30mA RCD could trip anywhere between 15 and
30mA?).Given we wanted the CU replaced with a split load unit anyway I got him to do that putting just the sockets circuit and kitchen sockets circuit on the RCD side. That was 2 days ago... since then, so far (fingers crossed), we've had no trips at all! The test certificate indicated that all circuits were OK.
So great minds out there... what could have been causing the original problem? Can a CU or MCB become 'faulty' in such away as to cause such a problem?
All very confusing....
Ben
In my house I had orecisely teh same problem. Never tracked it down to anything partucular - just general leakage from many items of electronics plugged in seemed to be enough to set the trip 'on the edge' and then almost any surge would take it over.
Now equipped with 100mA RCD overall..mmust split the bus sometime...and put 30mA on teh critical bits.
However its still sensitive enough to pop under various faults - had a leaky kettle..two in fact. Now down to zero electric kettles from three originally. All showed a minor leak to reath from the elements. All now binned.
That's right, and ~20 mA is a perfectly normal trip current for a 30 mA RCD. I would expect an electrician to have known that.
No, I suspect the intermittent problem is still lurking somewhere in a circuit now on the non-RCD side of the new board.
reckon you did the right thing there.
Possibles: an appliance fault combined or variable normal healthy leakages (immersions are famous for this, ditto other water heating elements)
Did you test all your appliances? If not, check L&N to E resistance with the multimeter, that will pick up leak faults in almost all cases. Dont do the classic mistake of not switching the appliance switches on first :)
Re your last question, a faulty mcb cant cause an RCD trip, as there is no earth path for fault current. Faulty CU? Theyve been known, pretty unlikely though. Far more likely to be an appliance of some sort, or an occasional intermittent fault in the wiring. Megers usually pick up the latter though, since they test at higher V than mains. But no absolute
100% guarantee there.NT
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