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rcd tripping out even when some of sockets on cct have been disconnected from supply,tried swapping over cooker cct to see if it was problem with mcb/rcd,no trip.any ideas?

You could have faulty RCD or loose connection within the circuit. Has it just started doing this, does it trip all the time or just random trips. What kind of equipment is plug in to this circuit?
KB

This is a split board with only sockets,cooker and water heater on rcd side,tried removing lives/neutrals/earths for skt cct,leaving cooker and water heater on rcd,no trips.Split ring in at least three places,but rcd trips as soon as I try to switch on mcb for sockets.

First obvious question to ask is - have you unplugged ALL appliances from this circuit?

There may be other things connected to the circuit that may be affecting RCD that you may have overlooked like central heating spur, outside flood lighting, garage lighting could be spurred off or even the feed to garden shed.

Once you've dismissed all these possibilities and are still having problems you need to track down the fault by a process of elimination.
Disconnect one leg of ring at cons unit and split ring wherever you estimate mid point to be.

Now try trip. If it holds test all sockets to see which are live. All those sockets are OK and can be eliminated from search. Fault is on other leg of ring.
If it trips disconnect from CU, connect other leg and try trip again. Chances are it will hold and again you can test which sockets are live and eliminate them.
You now know which leg fault is on and which sockets are affected.
Pick another socket and disconnect it. Swap legs in CU & try trip again.
If it holds then check which sockets are live and eliminate all of them.
Fault now lies somewhere in remaining sockets.
If it still trips reconnect first socket you removed, swap leg of ring in CU and try trip again. Check all live sockets and eliminate.
Fault now lies within remaining dead sockets.
Carry on this process until fault is tracked down - sometimes not easy and very time consuming!!
Of course all this would be much better done and much safer if suitable test instruments were used to track down fault.
Try to think of something obvious that has been done recently that could help you to pinpoint fault.
Have you had any carpets fitted? Have you hung any pictures by knocking nails in wall? Have you had water leakage anywhere? Have you bought a new appliance which could have an earth fault?

Mine turned out to be central heating boiler which I had to replace. OUCH!!!

Check your sockets for loose terminations, most faults can be found in the accessories. The RCD pick up any unballanced phase and neutral currents.
Does the MCB stay on when RCD trips, is this a new installation or has this problem just started on an otherwise healthy system?
KB

Sorry it has taken me so long to get back,in answer to brownie,yes the breaker stays on when rcd trips,have passed on problem to leccy who is scratching his head.

Did your electrician do a test on the rcd to make sure it was functioning correctly, the other faults could be on your appliances. Have you tried disconnecting them and pluging in them in one at a time.
KB

[quote="kbrownie"]Did your electrician do a test on the rcd to make sure it was functioning correctly, the other faults could be on your appliances. Have you tried disconnecting them and pluging in them in one at a time.
KB[/quote] :wink:
Thanks for advice,leccy has found problem,told me it was dampness in walls affecting cables,cct now back on and so far no more trips.

Good to hear your sorted out.
KB