replying to John Rumm, Yam man wrote: Hi john can't get lend of multimeter till Friday. Went ahead and fitted both sockets and the lights both on fused Spurs as explained in previous post. I'm having a problem over today my wife said the cu is tripping off. It's just happened whilst I'm home and ther is no breakers tripping off it is the main switch it is100amps 100ma rcd that is tripping off. I have the newly added sockets etc all turned off at fused switches I'm stumped any suggestions greatly appreciated
replying to Andy Burns, Yam man wrote: Hi Andy yes He has taken 2 fused Spurs from lighting curcuit both 3amp fuses. He also taken a spur from power curcuit all cables are 100% correct. He is now in process of going over every connection that he has moved used etc. He has replaced 4 socket fronts and a back box in kitchen also checked all these. He is suspicious of the fused spur that is used for washer as when replacing the switch he says the wires were looking old slightly covered corrosion.
replying to Andy Burns, Yam man wrote: I've found an earth wire hanging just out of bathroom wall hidden behind pedestal from sink this morning and pulled it through enough to wrap some around the cooper pipe supplying my bathroom sink until buying earth clamp tomorrow can this be some of cause?
replying to Andy Burns, Yam man wrote: Making sure my lighting curcuit was done correct. I just cut the lighting cable in loft that runs between my bathroom and my bedroom lights joined them in a junction box and just wired the fused switch into this. This is correct yes?
replying to tabbypurr, Yam man wrote: That is the reason I' have been asking for info help advise for 3 months now so I can find out exactly what I'm doing. So if you can tell me what to do then I can do the job I want to and pretend like most people that I know what I'm doing. If people who know what to do don't advise then I will never get to learn. So what should I be doing? The tripping was down to a faulty connection on my 1 of my downstairs lights the ceiling rose had dropped from ceiling due to old bath leak we fixed awhile ago. The cables where just say clamped into the connections real loose and probably contacting I have replaced this at 1am this morning had no tripping since. So for all those doubters who say I obviously don't know what I'm doing. YOU ARE WRONG! I've installed 2 double sockets have 2 lights added to curcuit and all is great. Thanks to all who helped and boo hoo to those who wouldn't help and doubted me. Great forum around 90% people really helpful other 10% are just snobby people thinking they are better then anyone who isn't experts in this matter.
Are your fused switches single or double pole? If single pole then the most likely cause is an earth to neutral short on the new wiring somewhere. That tends to have the effect of causing random RCD trips, since although both neutral and earth are notionally at the same potential, the neutral voltage will tend to rise slightly as the load on the circuits increases - and that can yield enough current flow to earth, to create an imbalance the RCD can see.
Firstly, chill, don't get too worked up about it. ;-)
This is usenet (the web site you are using is just gateway to it) - and there are a huge number of people on this group. So there is always going to be an element of damned if you do, damned if you don't. Some folks will offer constructive help, others will snipe from the sidelines, and a few will just want to willy wave. Over a period of time reading it, you will get to know which names to trust one what subjects.
In my opinion its always better to ask questions if unsure. (its better to speak first and be thought foolish, rather than act first and prove it!)
When answering questions I will give the questioner the benefit of the doubt in most cases. However there has been the odd time where the nature of a question or the way its asked may throw up a warning sign that the questioner is getting out of their depth, or might be putting themselves at risk, at which point advising them to slow down a bit can be worthwhile. So folks are more cautious than me, and will adopt this kind of response with less provocation.
Loose connections alone can on occasion cause nuisance trips, especially if you get arcing at one of them. Although its unusual to trip a RCD with a 100mA threshold this way. See the sensitising RCDs section here:
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(it sounds like this is a "whole house" RCD, so its possible that the total leakage of all the circuits combined is soaking up much of its trip budget)
Once you get your multimeter, do the tests we described before, and also one the lighting circuit with all the bulbs disconnected or the lamps switched off, check you read a completely open circuit between L N & E on the highest resistance range the meter has.
Just wait til you get em arguing about politics ;-)
How does anyone get by without a multimeter? They're cheap as chips and useful for anything from checking fuses and batteries to serious electrical/electronic troubleshooting. Something like this
replying to John Rumm, Yam man wrote: Hi john the fused switches used are all double pole I've checked all my junctions connections and can't find any problems. I've fitted the 2 double sockets on fused spur they are metal clad surface mounted single pole double earthed sockets. I've also replaced 3socket fronts around house as they had been damaged and needed changed these are single pole double sockets also. So is this possible the culprit? Thanks for all the help advise you have given. I don't normally go off on 1 as I seem to have done last night. Really bad day then came home to find problems with rcd tripping never mind no offence intended to other persons.
replying to Rob Morley, Yam man wrote: Rob it's a tool as a mechanic I don't tend to use much rather stick with old school light testers etc (until all new cars will be ran by software and no drivers or engine needed) last multimeter I had was lent to a family member or friend and never returned. I will be getting 1 in near future of my own but never really had much to do with diy electrics (apart from changing bulbs) always had someone else do it but time is money and I've saved quite a bit doing it myself.
replying to John Rumm, Yam man wrote: Hi John I have traced all my new wiring back and disconnected the fused spur from my sockets I have removed both fuses from the 2 lights I added. The tripping got worse to the point last night we couldn't reset it as it tripped straight off. I've tried switching different breakers on and off it will still trip even if all breakers off and just main switch rcd on. I fitted 5 new socket fronts around house at same time and disposed of old 1s. All are single pole double sockets. I've removed them all and put block connectors and covered in insulation tape. I'm now got downstairs lights and sockets only and it still trips. Any ideas insight advise on what I can do greatly appreciated. Did manage to get multimeter but red prong is missing it's just bear wire to use. Will get
If its tripping with *all* the MCBs off, then that suggests its most likely a faulty RCD. (RCDs work by sensing an imbalance between current flowing in the live and neutral - with all the MCBs off then there should be no current in either in the absence of some other more esoteric fault)
You could prove it if you are happy to open the consumer unit itself.
With the main switch off, and all MCBs off, you could disconnect the neutral out of the RCD where it connects to the neutral bus bar (it will be a big thick black/blue wire that normally drops out of the bottom of the RCD and goes up to the bus bar where all the circuit neutrals end). Then if you switch on the RCD, then the main switch, and still get a trip, its knackered.
You mentioned that the RCD was one with a 100mA trip threshold... That seems slightly odd, since you would only normally see that on places that don't have a proper earth provided by the electricity supplier, and as a result need to reply on an earth stake (what's known as a TT system). Is this the only RCD you have or are there others?
If its the only one you have, and you are *not* TT, then its not actually doing you much benefit anyway (the trip threshold is too high to protect you from a lethal electric shock). So you could safely simply bypass it.
Have a look at:
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(might be handy if you post some photos of your fuse / meter / CU if so we can be sure)
That looks like you have got a classic 16th edition "split load" style TT install since I can't see any earth connection from the main cutout. (quite neatly wired in the CU as well)
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The RCD in question is a type "S" which means it also includes a time delay - this allows discrimination with the 30mA trip RCD you have on the left hand bank of circuits. (i.e. if there is a earth fault that causes 150mA of leakage on one of the left hand circuits, the delay gives chance for the 30mA device to clear the fault first without tripping the upstream RCD)
So given that, you *can't* just bridge out the RCD since there is no guarantee that your earth impedance is low enough to clear a fault on the right hand side bank of circuits without it.
If you are still getting a trip with all the MCBs off (and other RCD), then its still likely to be a faulty RCD.
There is one other possible cause, and that would be if you have N to E short circuit - probably on the lighting circuit you have been extending. If this fault is combined with a slight voltage rise on the neutral of your supply (which can be caused either by your own load on it, or a neighbours), then you can get a trip because a little bit of current flows through the neutral of the RCD to earth, and that is not balanced by equal current in the live.
You could test for this by measuring the resistance between your rightmost neutral bus bar, and the earth bus bar (with everything turned off obviously). If you get a low resistance, then disconnect the neutral wire into terminal 2 on the right most neutral bar, and measure the resistance to earth from that in isolation (i.e. testing just the circuit you know you have been working on).
(Note I am assuming its been wired with the neutrals into the numbered position matching that of the corresponding MCB!).
If you wanted to test the main RCD just on its own, again everything switched off. Disconnect the two thick wires into the two right hand terminals of the right hand neutral bus bar, tape the ends just so they are not flapping about, and turn the main switch on again. If it trips then it must be faulty.
A suitable replacement would be something like:
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(note however replacing that would mean pulling the main switch in order to work safely since you have no other way of turning off those live meter tails coming into the top of it)
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