Hager Split CU, RCD now nuisance tripping.

[Matt Smith]

Sorry pencil pusher no, CU was not tested before the change out, only after the install.

 

[lurch]

can i be your mate, mate? you seriously been had!!

 

[lurch]

"I am therefore unsure if it's tripping on earth leakage or possibly overloading without taking out the mcb ?" . . . oh be advised an RCD does not offer overload protection, only earth leakage. An MCB or RCBO will offer overload protection. . . . . mate


Read more: http://www.electriciansforums.net/e...-rcd-now-nuisance-tripping.html#ixzz2LZY28BYt

 

[Matt Smith]

Yep I do know that RCBO is overload also but I have had peoples laptop chargers cause enough leakage to trip an rcbo or rcd before so am thinking that the combination of a fridge compressor, and washing machine too will be plenty enough leakage to earth to trip out a 30mA rcd..
Thanks so much for making me seem a total cock though guys.. Nice. I mis-typed that's all.

I may seem to have paid too much, but I was willing to cough up so that I knew that the home was tested and safe that's all.

 

[pencilpusher]

Yep I do know that RCBO is overload also but I have had peoples laptop chargers cause enough leakage to trip an rcbo or rcd before so am thinking that the combination of a fridge compressor, and washing machine too will be plenty enough leakage to earth to trip out a 30mA rcd..
Thanks so much for making me seem a total cock though guys.. Nice. I mis-typed that's all.

I may seem to have paid too much, but I was willing to cough up so that I knew that the home was tested and safe that's all.

But it was OK before! There will be a faulty appliance somewhere.

 

[Matt Smith]

Thank you... going to have to try find out what is causing the leakage now, sorry for wasting your time guys.

 

[plugsandsparks]

Disconnect all appliances in kitchen, reset RCD, bring in one appliance at a time, slowly, if you have a clamp meter us it to detect differences in L and N.
cheers

 

[Engineer54]

I'm not understanding this at all!!!! How can any electrician work without any test equipment to his name?? Is the OP self employed or is he engaged in employed electrical work and only does a bit of domestic work on the side?? Probably the latter!!

He obviously isn't registered with a scheme provider, if he doesn't have the required test equipment, so i don't know what's going on, that's the only reason i can think of, to pay someone else to test for you!! lol!! Now if this CU cost £300 to test, how much did the whole CU change cost this customer???? The mind boggles!!...lol!!

 

[electric will]

Ok so no testing done before cu change? I fell foul of that once, and only once!!!
What's the insulation resistance test results now, i mean after the boards been changed? Not all but just the ones from the side that the rcd is tripping will do.

my money's on the water heater, what about everyone else?

 

[Midwest]

I'm putting on my tin hat here........I do grow weary of people, albeit perhaps not ‘Competent’, posting on this forum and being ridiculed for their lack of knowledge, skill or expertise. I think Matt realises he needs to carry out tests to establish the root of the problem. I sense from his tone though, he wished hadn’t posted in the first place. I suspect he thought he could use this forum to broaden his knowledge by getting advice from experts & experienced electricians. Perhaps this stance will encourage the budding spark to go away and get properly trained.
To think that is the case is pure utopia, and I fear some might not dare post & just go and‘takeaway the rcd and put in a main switch’?

 

[imago]

If we set aside Part 'P' and testing with an MFT for a minute, you still can, and should be able to carry out tests. People were testinmg installations long before the dual 'cure-alls' of Part 'P' and MFTs came along.

So, you shouldn't assume or guess that earth leakage from the new appliance is responsible. It may well be a red herring, and possibly cost you a great deal of time looking for a fault which doesn't exist.

Back to basics, disconnect everything on that circuit. Does the RCD still trip? If it does, investigate the wiring. If not, reconnect the appliances/equipment one at a time and operate them. Does it trip out? If yes then you've narrowed the fault down. If no then get them all operating together one at a time until it does.

95% of electrical faults can be found using very basic principles and a systematic approach. An MFT will speed up the process, but basic test kit will quite often get you there. The issue being that everyone wants to sort out a fault in an instant and rushes the job. There also seems to be a worrying lack of understanding when it comes to basic principles generally as the younger/newer qualified sparks seem to be taught stuff parrot fashion when it comes to calculations and testing, rather than building up to that from the basics.

 

[Heisenberg]

There also seems to be a worrying lack of understanding when it comes to basic principles generally as the younger/newer qualified sparks seem to be taught stuff parrot fashion when it comes to calculations and testing, rather than building up to that from the basics.

Like the OP's misguided belief that the RCD in question provides overload protection.
Everyone's got to start somewhere but to think that someone could possibly be about to sit the 2391 written, and not understand something as fundamental as that, probably illustrates your point perfectly.

That aside, I've very little sympathy for people who undertake board changes without having done any form of testing, and then come a cropper. Also, the fact that the guy is doing installs but does not seem to own any testing kit, is hardly something that should be encouraged.

Cheers

 

[imago]

A few months back I showed a fully qualified spark how to find a L - E short in a lighting circuit. He seemed amazed and was very enthusiastic about learning a 'new way'. The house was being refurbed (replastered, wiring changes, loft insulation, new kitchen, bathroom etc) and second fix going in.

This mysterious technique which caused so much excitement and interest was nothing more than following the upstairs lighting circuit and looking for a reducing resistance, then increasing using a multi-meter. It took twenty minutes to narrow it down to the area above the landing, then find the screw through the cable in the loft.

It wasn't that he was tick, or bad at his job, he was simply too reliant on his MFT and his training was too focussed on formulas, RCDs, and the like IMHO.

 

[Colin Jenkins]

Hello Matt.

Ths is fault-finding now rather than "Inspection", so don't get too hung up on documentation The RCD is operating intermittently; these devices are very reliable so it's 99.99% certain it's seeing leakage of current to earth and doing its job correctly.

If the building has solid walls and flush electrical accessories, with all the rain we've had in the last 12 months the ingress of moisture is a possibility. It does not even have to be visibly damp inide the accessory, just humid - that will be enough to cause the 30 mA RCD to operate.

Perhaps the easiest way to spot which circuit is in trouble is to use an earth leakage clamp meter. With the circuit in normal operation, the clamp meter is closed around Live and Neutral and the imbalance is displayed directly in milliamps. All circuits have little bit of leakage, but if you find one reading 15 milliamps or more, then that is likely to be the source of the trouble. Read each circuit individually and write them all down - it's surprising how the milliamps tot up on some installations.

The Fluke 360 and the Megger DCM300E are both earth leakage clamp meters that would be suitable for this. They cost about £300 each, but are incredibly useful test instruments that will get plenty of use on other jobs. They sometimes appear on E-Bay, or you may be able to hire one locally to sort this earth leakage tripping out.

This is live working, so take care.

I hope this helps.

Regards,

Colin Jenkins

 

[BlueToBits]

Thank you... going to have to try find out what is causing the leakage now, sorry for wasting your time guys.

You are not wasting anybody's time, We've all got time to 'waste' anyhow, if we didn't we wouldn't be here. There will always be those that will shoot you down, It's often difficult to express the something you would say out loud with the same meaning in typed words. That's the nature of forums. Remember that comments are merely opinions, they may or not be factually correct, and I include my own in that.

Having said that, in my opinion, irrespective of what exams or courses we have or have not taken, if we are undertaking installation work, we should always test it. We should understand exactly what we are testing, why we are testing it, and the significance of the test results. Until we are sufficiently conversant with this our electrical work may be at risk of harming someone, not least ourselves. Whether or not any of us decide if we can sleep soundly ignoring this is ultimately up to ourselves and our knowledge and assessment of the risks pertaining to job in hand. Again, it's only my opinion, but the really 'dangerous' electricians are those that work without realising this.

The regulations require that a minimum series of tests are carried out for any particular job, fault finding usually requires much more than this minimum.

 

[Midwest]

Hmmmmm, much better :wink5:

 

[Matt Smith]

O.k. so I have messed up by not testing, I have learned the hard way and just tonight bought a whole 17th edition test kit to replace the Megger 1553 I sold before due to redundancy and two toddlers in the house. I appreciate the slaggings from people like Lurch and others... and I also really Thank Colin, Blue to bits, imago and many others for their experience and teaching me something new going forwards. I am competent and have completed many tests before but on this occasion I failed myself and a customer. I will also like to after all remove my access to the forum and if anybody can tell me how I do this, I would very much appreciate it. Thanks again to the few who do not just want to put people making mistakes down, anyways the person who never made a mistake never learnt anything, I heard...

 

[imago]

OK, you fuc, er, messed up. People have done worse. No reason to leave the forum, there are some very experienced sparks on here and if you stick around you'll learn loads as we all have from them.

Keep it in perspective, take it on the chin and move on

 

[Midwest]

I rest my case. If you'thesaurus' forum, one hit is opportunity. Lets not forget that.

 

[Octopus]

O.k. so I have messed up by not testing, I have learned the hard way and just tonight bought a whole 17th edition test kit to replace the Megger 1553 I sold before due to redundancy and two toddlers in the house. I appreciate the slaggings from people like Lurch and others... and I also really Thank Colin, Blue to bits, imago and many others for their experience and teaching me something new going forwards. I am competent and have completed many tests before but on this occasion I failed myself and a customer. I will also like to after all remove my access to the forum and if anybody can tell me how I do this, I would very much appreciate it. Thanks again to the few who do not just want to put people making mistakes down, anyways the person who never made a mistake never learnt anything, I heard...

Matey, one of my first posts was so badly laid out I got absolutely slated, and deservedly so...... but it taught me a lesson and look at my count now!