Fault Finding - You Will Never Guess What It Was...

i've just got a call from one of our regular customers an elderly couple who are in a bit of a panic because they've got no power it's snowing outside they're getting cold and the husband is really unwell anyway grab some test gear some screwdrivers and hand tools and stuff and just just go over there and see if i can sort it out for them yes so it had tripped well it's gone off again now so there is a problem somewhere so if i just try the sockets and the other circuits and if we leave the heat pump off you might find it'll stay on and it might be an issue with the heat pump [Music] right so the socket circuit is working okay at the moment that feels a little bit loose but if we just try the cooker circuit and see what that does see if it trips what's the other thing central heating that's staying on okay central heating is the problem all right so i'm gonna have to do insulation test i think right so insulation testing is showing a fault between neutral and earth on the cooker circuit so i'm going to investigate that further the other circuits seem to be okay because when we do neutral to earth on those we have 137 meg ohms so that's fine so i'm going to test line to cpc now and we've got 0.01 so that is our issue there with the cooker circuit so i've isolated the cooker switch now i'm just going to check that again it's quite likely that it's just a problem with an appliance although it could be the switch itself okay yeah that's all clear now we've got 200 meg ohms there so let's test to neutral as well just to see and that's all clear too so let's reconnect that and see if the rcd still trips right that is reconnected so i'm gonna just reset the lcd now and turn everything on and see if it stays on there's no reason why it shouldn't really now because the insulation tests are all good so and then it's just a case of minimizing it down to know which circuit how's the which which oven has the problem or or if it's something on the outgoing side of the cooker switch that we need to check seems to all be good now so i'll just isolate that circuit again and then i will check the cooker switch [Music] [Music] so basically the issues here with this little connection plate somehow there's a short between cpc and line here not dead short but enough to cause tripping problems here's a close up of the other side and i've basically disconnected everything so i'm literally just testing between the cpc and the line terminals and it's giving us giving us a problem so it's basically i've disconnected all the wires from the back of this now and literally just tested between the terminals between the earth terminal and the line terminal we've got 0.2 mega ohms it's clear between the cpc terminal and the neutral terminal between line and neutral i'm not sure i'm going to check that now so i've disconnected this terminal now i have no idea how it's shorting out inside but it's very flimsy plastic so it's it's easily possible that that is happening i'm just going to disconnect the cables from this other side as well just to make sure that it's nothing with those cables do one final check so now if i test between the casing which is obviously connected to earth and this one this is the live terminal okay saying it's all clear now again oh yeah okay all right so this is strange all right it's back to square one [Music] there could be a short in one of the elements and you would not know about it well okay all right so that's how these are supposed to be but they were they were the wrong way around i believe if we look back at how it was before i disconnected it which means that there could be an element that's gone like for example this one and because it was directly livened up on the neutral side the whole time it could short and trip the rcd even though the oven was switched off if that makes sense wow okay let's try testing this okay so i can put that back now that makes sense why i was still getting bad readings even though i disconnected this life that was really confusing me but it's actually quite logical when you think about it so those can go back as they were and basically i think what will happen now is that it will stay on until we turn the oven on and then it will trip the rcd because i think there's probably an element that's gone in fact what we could probably do is just do a test on all of these items before we put everything back together so let's do that's the cpc let's do a test on this fan motor and let's disconnect these and test the element usually elements are things that go yep 0.02 to that element on both sides between cpc and if i just test now to the actual live wires in this if i put everything back together and just do a test right so what i've done now is i've just been going through the various elements in this oven and i've disconnected this element which is usually the classic one that goes wrong disconnected the live and neutral wires for that and i'll show you if i test now between both sides and the cpc we've got our dodgy reading still of 0.02 mega ohms on both sides we've got that so that is our problem it's the element that's gone and now if i test to um to the live so live to cpc we're all clear 200 meg ohms and neutral to cpc we're also we were clear i just checked it a minute ago 200 meg ohms so we're all good so it's literally just a dodgy element which is easy enough to replace which is quite a relief okay so we've got um i've explained to the customer basically that the element is is dodgy so i'm going to re i'm going to take this element out from inside the oven and then i can get a replacement spare part that will match then i'm going to put everything back together so that at least the hob will work although i'm not quite sure where the hobbit's wired up to to be honest um but we'll get that working for them get the oven back in the hole in the wall so that that's sort of safe and there's not an oven lying on the floor and then hopefully all it's doing is a case of just replacing the element the weird thing is that i would have figured that out much quicker if the live and neutral hadn't been the wrong way around in the connection plate so it that was the mystery of this fault was the fact that because the live in neutral were the wrong way round the polarity was reversed the fault was showing up even though none of the oven switches were on whereas usually that fault wouldn't show up and it would be a case as soon as you turn the oven on pop it would trip the rcd and you'd know straight away what the fault was then but in this case manufacturing issue i think because basically you know this is how they've done it right from when it was built so probably whoever did it in the factory just didn't pop the wires on the right terminals and that has resulted in all of this problem which would have been so much quicker to find if i if they'd have got the polarity correct [Music] [Music] so just to confirm that it is the element can you see that it's got a slight split in it very very slight but that's enough to do that 0.2 meg ohms reading which is all it takes to check the rcd tiny little bit of earth leakage current on there and that would do the trick what a palava to find that two faults in one okay so that is um the covers back on in there i'm just going to sort of make everything safe in here i'm actually just going to leave it disconnected from this so that there's no power going to it at all until i can come back and replace the [Music] [Music] element right now this is something that always annoys me and worries me why is it that you put everything back together and there's always one screw that's left and you're like where does it go can't find it anyway everything seems to be back together now as far as i can oh it's the middle one here ah there we go that's good so um yeah basically everything's back together i'm just gonna leave it disconnected but i'm gonna put it back in the hole in the wall so that it's out of the way and then um see if i can order a spare element from one of these online spares people and then that should do the trick so that's back on now and uh everything should work as expected now right so that's all back on and working everything is on and staying on which is good so we'll try and get the heat pump started up for them again and then i'll be all good to go right well um i'm glad i managed to get that sorted bit of a tricky one that that was much more tricky than i expected i thought it was going to be an easy fix today but you just never know so it's taking me about an hour and a half to sort of sort all that out while just over an hour really right so i'm back in the tesla heading out to do a few errands now i'm gonna get home and order that um element if i can get one from one of these spare parts websites hopefully i can it looks fairly standard so it should be okay but at least we've got the power back on for them they've got a bit of warmth again poor things because they've been freezing to death for the last few hours um and that's it as always if you enjoy my videos don't forget to smash the thumbs up button and share it out with someone else who might enjoy it and thanks for watching see you on the next one

Channel: Artisan Electrics

Views: 144,564

Keywords: artisan electrics, electrician life, am2, megger mft tester, how to fault find, how to pass am2, electrical fault finding, megger ohms, how to pass am2s, testing and inspection, low reading insulation resistance test, am2s, fault finding, inspection and testing, city and guilds 8202, finding electrical faults, how to find electrical faults, help with am2, how to carry out an electrical test and inspection, electrical inspection and testing

Id: GqUxUDLdjTo

Length: 13min 46sec (826 seconds)

Published: Mon Dec 07 2020