DIY Doctor

Random Tripping!

Postby Kags02 » Tue Mar 04, 2008 9:20 pm

Can anyone give advice here, house was rewired during renovation in 2006 since then we have random tripping of electrics. Pardon my ignorance here but we have a earth switch on our electrics board which trips out sometimes daily then not for weeks on end. Electrician blamed the pc but it happened when this was unplugged so that's ruled out. Only sockets trip out lights remain on. It's driving me insane, can anyone shed any light??

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Postby ericmark » Tue Mar 04, 2008 9:54 pm

The earth switch as you call it or RCD measures how much electricity has escaped. It may escape or at least appear to the device as escaped where switch mode power supplies are used. Your computer, video, even phone charger all work this way and what you get is a build up of all the little bits which all together add up to enough to trigger the trip. The more we can split up our circuits the less likely that they trigger the trip due to cumulative leakage. It can also be triggered by spikes like those caused by thunder storms or some one welding even if not in your house. Although all the trips have to comply with regulation 415.1.1 they are not all the same and some are more resistant than others to nuances tripping. But at the end of the day it all comes down to money. If for example you have a split board with 6 MCB’s connected through the RCD and you instead put each one on its own RCBO (That’s a MCB and RCD combined) then it would cost £180 just for the units without fitting. But instead you may opt for just some circuits like that feeding your freezer and each circuit taken off the main RCD will help. The only problem is the electrician needs to replace the bus bars in the consumer unit and how easy it is to get replacements will depend on the area you live and make. There is most likely nothing wrong with what you have and the electrician is not wrong in what he has said all I am doing is telling you how you can improve things.

Postby Kags02 » Wed Mar 05, 2008 1:08 pm

Thanks for your reply, sorry if I appear totally thick but I know zilch about electrics (only how bloody expensive the bills are!)

Is it possible for this to be caused by power surges?, is there any way we can find out exactly what's causing the tripping? Our biggest prob is that it happens when we are away causing boiler to go off. We have thought about getting another electrician in to check everything out, is this recommended?

Again apologies for my ignorance in this.
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Postby dr.sparks » Wed Mar 05, 2008 3:04 pm

hi troubled houseowner

this kind of problem is a pain in the a**
without havin a good spark look at it

nuisance tripping could be caused by many factors

assuming you had no trips b4 it is likely to be caused by your
equipment rather than the rcd
can you answer is your house in the countryside or fed from overhead cables
also try laeving all equipment unplugged until you need it then plug it in one by one to see if this solves it
usually things like wash machines tumble dryers are problem items

let me know
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Postby sparx » Wed Mar 05, 2008 11:42 pm

Hi, If RCD trips either it is over sensitive(unlikely) or there is an earth leakage fault. To find out will need some test equipment in the hands of someone who knows how to use it! Many testers can check RCD tripping point (actual mAmps- not as rated). also insulation check on circuits at consumer unit, and my favourite is with a very low reading clamp meter around each out going L&N pair of circuit cores which can be done with appliances switched on, suggest showing this to leckies until you find one who can do all this,
regards SPARX
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Postby ericmark » Thu Mar 06, 2008 2:32 pm

As sparx says RCD’s normally fail within very short time of fitting or work for ever and a day. Yes I have tested RCD’s with the expensive meter and they have shown as OK but on changing the fault went and new one gave same results so a meter will show if faulty but not always that they are good but they fail on safe side.
Spikes and damp can both cause problems and by time an electrician gets to you the fault may have gone. So some pointers Cookers can absorb water but once switched on quickly drive the water out again which is why some electricians don’t put them on RCD so switch of cooker at the wall when not in use this may reduce it and if it is the cause may trip out as you switch it on so pointing to the fault. Most electronic equipment have things to stop interference and these can also build up with the amount we use so again unplug or switch off at the wall. Many items only switch the live so even if not in use can cause an earth fault so again unplug or switch off at socket these are normally double switches and also switch the neutral. And make notes when it does trip. What was plugged in. Not only what was in use but what was plugged in. The low reading clamp on meter is not too common but PAT testers are and if you have worked out it is most likely one of eight items the PAT tester can show which one. But careful notes is way forward. As I said before there are other things that can be done to split the circuits but this is expensive.

Postby » Mon Mar 10, 2008 9:10 am

Had a similar problem a few years back after moving into a house.

Honest sparks admitted he was baffled after separating all the rings to try and isolate the problem.

Finally traced it to a wall socket that had been knocked very slightly sideways bringing furniture in.

The live shorted to the earthed patress (spelling?) under vibration.

Been moving furniture lately?
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Postby ericmark » Mon Mar 10, 2008 11:24 am

Since my last post I have found there is an automatic resetting RCD on the market it also tests itself every 7 days but at £250 per unit I don't think I will be fitting any. It tries to reset 3 times before going into manual mode. I think I will still reset mine manually?

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