RCD Tripping, Nothing in Sockets, no load... what now?

[Tidy]

Hi Everybody,

We just moved into a detached house in last friday, only to find that the RCD keeps tripping for no reason :S I have had an electrician out who checked the RCD and said the box is fine.. and must be the sockets.

We unplugged every item in the house and tried to turn the socket switch back on (on the CU)... it trips the RCD, after 4 or 5 attempts it holds and we have power. (lights etc are not affected).

If we press the test button the RCD main switch does as it should.... and if we turn the socket switch OFF the main RCD will switch on immediately and hold. If we start to plug items back into the sockets sometimes it trips... sometimes it does not... there is no pattern.

I have pulled all the sockets away from the wall to make sure there are no trapped wires and for any interference with the back plates.. all ok, and still trips for no real reason.

The electrician (as above) has tested the CU with some little plugin things and said its fine and working as it should.

The worst time is the morning (between 8 - 10am), there are no washing machines on, no dryers, the combi boiler is off.. so essentially no load at all.

Other notes of interest is the previous owner who i have contacted (because of mail he needs to pick up) asked about the electrics... his words were

"its the shower, if i wanted to use the shower i had to make sure the washing machine, dryer and microwave was off). I had all the sockets tested and my electrican could not find anything wrong with the wiring.

Surely that would affect the shower switch... and not the sockets switch (the shower is not on the sockets - tested that lol).


I am sorry to pick everybodies brains, but i will go through when it has tripped and see if somebody is blatantly obvious?

1) Plug in extension cable with nothing in... Sockets RCD flicked as well as main RCD
2) Plug in hoover into kitchen socket.... main RCD off
3) Walking across the landing towards the shower... main RCD switch off
4) Jumping on the landing floorboards...no change (in case of rogue nail in floor boards lol)
5) Turning TV sockets on (which has an xbox, DVD player, 50" plasma, Wii), sockets rcd off, main switch off
6) 2 minutes into a shower, sockets off, shower off, main rcd off

This morning when i was just about to have a shower and had to reset the main switch, when i managed to finally get all switched to stick there was a buzzing noise coming from the CU - but it only happened when the shower was turned on (electric shower).

I am at a real loss at what to try next, with everything seeming to be checking out i seem to working (web designer) out of fear that my PC will shut down at any time with no warnings etc...

I am no expert but after many nights browsing the web and trying to diagnose the issue, would it be possible to think that it might be an earth problem for the house?

Thank you all again

 

[telectrix]

could be someting as simple as a bad connection on that circuit. does sound as if there is more than 1 fault , though.

 

[Edd]

Not sure if its relevant, or just the design of the extension cable... but i have a surge protector cable... which has a green light to show surge protection is "on".

The green light is flickering on the extension?

surge protection extention leads are notorious things for N-E faults, I think they have a surge capacitor that leaks to earth. ive had loads causing nucance tripping. And it only needs to be pluged in the wall and not even switched on or in use to cause a tripping problem

 

[Tidy]

@Edd that's quite interesting... i think i'm in the mind frame that the extenion leads worked fine at the old address and have tried 3 or 4 different ones with the same results (be it some do not have the lights showing surge protection). So if it is them i would be surprised, but definitely worth a mention to the sparky coming bright and early monday

 

[Mark_Burgess]

When you say everything unplugged, are you including fridge and freezer?

 

[staylor34]

Sounds like you may have the circuit neutrals crossed in the consumer unit if it's a split load board.

 

[kdsworld]

Had a similar problem 6 months ago with random tripping RCD. All new house wiring, so checked the usual suspect (crossed-neutrals on the split CU) and found nothing. Systematically unplugged appliances and was about to throw some away thinking it had to be one of them when I decided to change the RCD itself. 15 minutes labour and £20 later, problem solved and no tripping since. That beats the hundreds of pounds I wasted thinking it could never be a faulty RCD and the hundreds of pounds I would have wasted buying new appliances when there was nothing wrong with the old ones. Rather than paying your sparky for hours of testing why not get him to change your RCD and see what happens?

 

[telectrix]

can;t wait to find out what the fault/s is.

 

[Edd]

decided to change the RCD itself. 15 minutes labour and £20 later, problem solved and no tripping since. That beats the hundreds of pounds

did you test the new rcd? i know its new, but i do hope its fully funcional and trips within the proper time limits set by the regs.. RCDs do go wrong yep but 99 times out of 100 its not the RCD so saying change it and save money will work ,,, well only once in 100 and then them odds are conservative.. I wonder how many people are gona come back saying ,,,,, Ive changed my RCD and it still trips..

 

[Tidy]

Hi, yes fridge and freezer un plugged. All tripped again whilst eating pancakes lol. No load at all. Unplugged from a socket that had flickering surge protector light and no problems since. Shall see what happens tomorrow..... I must say its really annoying. But I'd like to thank everybody for their continued help.

 

[kdsworld]

Edd, I am not saying change it and it will work, I am saying change it and see if it works. Statistics sometimes blind even the most competent people to reality. The cost of an RCD is typically less than the cost of 1 hours labour and whilst it may make good financial sense to the sparky to carry on testing indefinitely it usually doesn't for the client. Anything which can reduce the amount of labour required is worthwhile trying. Safety is nevertheless paramount, but economics comes in a close second.

 

[Tidy]

Mornin!

Thought id give an update!

With things unplugged from that dodgy socket the RCD seemed to be fine... until sunday when the shower flicked on the main RCD tripped

So after we'd thought we'd cracked it - still the trips were happening

Electrician came bright and early yesterday morning, we gave him an update and pointed him in the direction of the dodgy socket...

He first ran insulation tests on our sockets circuit and all came back fine... no leakage, no faults... normal. Then he plugged a lamp into the dodgy socket, turned the power off and tried to turn the power back on...the sockets switch kept tripping.... plugged the lamp into another socket (in the same room) and things turned on fine with no problem.

So he took the socket off and changed the socket itself (my request). The socket also had 2 earth wires that had been twisted.... he untwisted them and put some green/yellow tubing over the top (cant remember the name lol). Connected all back up and tried again.....it did seem a little better

Then he left us to see how we got on... (he was coming back later in the day to replace an alarm battery)... no more than 5 minutes had gone and it tripped again...main RCD switch.

When he came back, he decided to "try" a new RCD switch just to see if the RCD had tripped that many times it was a bit "worn" - and even though it did pass the tests for trip speed, it might be over sensitive, or just somewhat faulty under a bit of load...

That was 1pm yesterday.... and no problems since!

So fingers crossed it might have been the RCD switch itself?

 

[SPARTYKUS]

Edd, I am not saying change it and it will work, I am saying change it and see if it works. Statistics sometimes blind even the most competent people to reality. The cost of an RCD is typically less than the cost of 1 hours labour and whilst it may make good financial sense to the sparky to carry on testing indefinitely it usually doesn't for the client. Anything which can reduce the amount of labour required is worthwhile trying. Safety is nevertheless paramount, but economics comes in a close second.

I'd be charging a minimum fee (1.5 hours) anyway to change the RCD. Drive there. Get tools out. put tools away. drive away.

Are you saying you'd change the RCD for no labour charge?!

 

[telectrix]

think what he meant was that by replacing the |RCD ( about 20mins) would save a lot of time testing if it was the RCD at fault.

 

[spark 68]

This type of situation is where an Earth leakage clamp meter starts to pay for itself.

 

[kdsworld]

I'd be charging a minimum fee (1.5 hours) anyway to change the RCD. Drive there. Get tools out. put tools away. drive away.

Are you saying you'd change the RCD for no labour charge?!

You are missing the point but telectrix got it!

The cost of replacing a low cost item like an RCD is minimal relative to the cost of labour involved in testing a fault such as this, which could amount to hours of work, particularly as in this case the source of the problem was not immediately evident.