Ring socket problem circuit fault finding using insulation resistance testing
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- Опубліковано 1 сер 2024
- We had a call to half the sockets in the house not working and the customer couldn't put the MCB on so we popped round to take a look at the problem using Insulation Resistance testing at 250V to find the problem and fix it.
American electrician here. Good troubleshooting. You guys are very thorough in your work. Carry on.
Thanks 👍
Great exforces guy doing really well. Ex Royal Navy retired electrician here. 👍
cheers Steven, we're loving all the latest prescribers & views, thanks for watching
Dean and Adam this was excellent a bit of fault finding -Delroy territory 😍 the voice over and explanation was just brilliant. That’s a great new spark UA-cam angle and works really well. This is brilliant content for the apprentices.
Thanks Math Man. Really glad you are enjoying the content we make as much as we enjoy making it 🤩
cheers Math Man, I was gutted when we lost the audio but the content was way too good to not use so we voiced over it
Have to say the RCD did it’s job imagine that fault without an RCD. Money well spent in resolving this by the customer. Saving lives guys keep it going.
Loved the voice over boys
You guys are good. That washing machine was a mad one to take out. Wouldn’t fancy that on a Friday. Great work ethic
Thanks Junaid for your comment, yes I hate moving washing machines!!
Thanks for watching 👍
What a great informative video.im a JIB spark and like to use a CPD, faults are fun and pleasing to find and its always something silly. Great stuff lads. Great point of test when unplugged and switched off.. I had 3 sockets customer put on he purchased off Ebay, switch was broke and shorted.
Hi Wayne, thank you for your comment.
Always unplug and test and do exactly in the video, most of the time it works, but when it doesn't that's when you get your head scratching!
Thanks for watching 👍
The reality of testing in domestic up to the 90s (that is being generous) may be a 500v swing of the megger/ring continuity would be top end. ( I started in 1975)
To remove appliances on lino I have small squares of lino. Put them under the appliance feet upside down. The appliances then slide easily.
Great idea👍🏼
Very good video
Don't think they would have got DIY Dave, must have been "Graham", "Fred's" mate, before he passed away!
Graham does keep us busy!!! Thanks for watching
Dean and Adam nice video thanks but I have a question, when you unplugged all the appliances and you checked again one set of cable with IR which was Live-Cpc and when you have greater than 199.9 you assumed the circuit was healthy but how do you know the fault wasnt in the L-N as you had it tested L+N against CPC so even if L-N had short circuit, it wouldnt show as you joined them together against CPC ?
Thanks again for the videos
My one socket circuit trips earth leakage intermittently. The resistance measures 20 megaohms is that bad?
For future reference, washing machines have "an interlock" on the door, when the door is open the live is switched off, you should always test with the door shut (and machine "on")
Maybe not such a good idea to meg an appliance tho with it turned on?
I never IR test with the appliance switched on
@@DoctorElectricUA-cam Good
I don't I/R test circuits with appliances still plugged in. To safely I/R test an appliance when switched on, make up a single extension socket with a short length of 3 core flex attached. Strip back about 75mm of outer sheath then about 25mm of the core sheath, twist the Live & Neutral ends together and solder securely. Twist and solder the end of the earth, plug the appliance into the socket & connect the insulation tester to the bared ends. You can I/R test safely with the appliance turned on.
To lift the front of an appliance over tiles on a floor use a small pair of air wedges, they take all the hassle out of it. Nice fault finding by the way 👍.
Good video gents, and a good methodical bit of fault finding there.
What you said about the Downlights was nonsense though, the old halogen lights don’t have drivers, they have 12v transformers, you wouldn’t get capacitive effect or charging up of the driver like you said. It’s just a coil, so it would either work or it wouldn’t.
The most common cause of that issue I’ve seen over the years is normally burnt out connector blocks. You see this a lot with old badly installed halogen fittings. Did you take any of them down for inspection atall ?
Thanks for your comment Darren, regarding the downlights I was just thinking on my feet and was puzzled at the time, didn't have time to take them out. Thank you for your advice though, it's really appreciated, every day's a schoolday! Thanks for watching
@@DoctorElectricUA-cam you’re welcome fella, you may even find they don’t have transformers atall and are just mains voltage halogens, with burnt out or loose connections.
Good work though with what you did 👍. You’re obviously conscientious about what you do, which I would expect from an ex member of the forces !
Also respect for filming your work and broadcasting it to the world, it takes balls to do that. Just prepare yourself for the keyboard warrior haters though ! 🤣
@@darrenqualters2341 haha, yes mate, no worries will do, comes with the territory though doesn't it
I'm not sure how common they were in the UK but you can indeed get electronic "transformers" for 12 V halogen lights. They were quite popular in Germany in the 90s and early 2000s because they were small, lightweight and most of all cheap. They put out constant voltage instead of constant current like LED drivers do but they do contain all sorts of electrolytic capacitors. Basically they're switching mode power supplies and these can fail in all sorts of interesting manners.
Good fly on the wall presentation. Please explain how the IR test failure was caused by the trapped insulation on the line conductor in the socket feeding the washing machine, there was no breakdown in the insulation, am I missing something? On second look, the insulation on the line conductor a bit further back looks damaged. But why would the RCD not catch this before the MCB tripped?
1) The IR test is measuring the leakage of current from one or more conductors to another when 500v (He is using 250V here) is applied to the wires. In this case its being measured between Live & Neutral and the CPC. As the insulation is damaged in the Live conductor, current is leaking to the CPC which leads to a low reading for the test.
2) The RCD will not trip because there is little or no Fault current to Earth.
3) What is happening is the tiny "Air gap" created because of the poor connection is acting like a resistor and heating up the wire which causes the circuit breaker to trip.
www.thespruce.com/breaker-tripped-by-loose-electrical-outlet-1824646
@@timg6850 Eeeeh... I've got a hard time following that explanation, I'm afraid!
A B32 (this is a 30 amp Type 2, which I think is reasonably similar in trip characteristics) trips instantly at three to five times the nominal current, i.e. 96 to 160 amps. Assuming the bang the customer heard was actually related to the fault, I'd rule out an overload trip (which would still have required at least around 40 amps for an extended period of time). If a current of 40 to 160 amps flows from the line to the CPC, any RCD should trip immediately.
Since the RCD never tripped, I'm fairly sure we're looking at a L - N fault far below one MΩ. Let's look at this from a different perspective!
In the event of a fault, the line voltage (230 V nominal) drives a current across the fault's resistance. The greater the resistance, the smaller the current according to Ohm's law. In order to trip a 30 mA RCD, the fault's resistance needs to be below about 12 KΩ (kiloohms, not meg!). For a B32 MCB, the resistance needs to be orders of magnitude smaller than that. Let's be kind and assume it trips at 96 amps. R=230V/96A=2.4Ω. Again, Ohms. Not kΩ, not MΩ.
Unless we're talking about a dead RCD (stuck in the on position) this was a L - N fault at the washing machine socket.
@@Ragnar8504 Yes, I don't t think this was an instantaneous trip. What I believe was happening is the wire has gotten physically hot from a high resistance connection in the washing machine socket ,say over an hour or two , and the bimetallic strip in the breaker because of the physical heat of the wire has tripped. This trip would account for the pop the customer heard as the circuit would have been under load at the time. The electrician in this video also talks about dampness so water in the socket may have been a factor as well.
Thinking further about it heating up of the wire doesn't seem likely. I can see a scenario where water has made a connection between the Live and the Neutral wires and tripped the breaker. Edit: It does beg the question why didn't the RCD trip?
How does connecting live and neutral together and testing to earth not cause damage to appliances connected?
Yes the Doctor will see you now 😎
hahaha
Try sum washing up liquid just under the feet slides easy or ask the customer for her slide and glide
Hi Tony, great tip there, I'll try it next time, thanks for watching
CPC, or Earth as we knew it, especially but usually all conductors were twisted to ensure continuity if screw in socket came loose. Not much point at fuse but done automatically. There were no regular tests. If no faults then installation was never disturbed for 30:yrs.
Great comment Alan, I did wonder, and yes you are right, I have been to properties that haven't ever been disturber for 30-40 years and the results are perfect
Hi. Nice video. I learned a lot. when you are pat testing do you charge by the hour or by the item, or a combination of both?
Don't know if you would suvive a night out with the legend who is Dave Savory.
We always charge by the hour
Is the low I. R reading not down to the neon light in the fcu?
Hi Chris, no, we tested L&N to CPC@250V which takes the neon light out of the question
@@DoctorElectricUA-cam I might suspect the Y filter caps in the washing machine, although around 1M is quite low.
RCD is on the right side of the consumer unit?
Hi Andrew thanks for your comment, the main switch is on the right(the red switch), RCD is on the left(black switch)
am i right in saying that you should test ring continuity first?
When you're fault finding a tripping circuit it's perfectly OK to go straight to IR tests
How long did you spend at the HMO before you realised you couldn't do the job?
Hi No. 1 fan, only about half hour
@Doctor Electric awww thanks mate ❤️
@@DoctorElectricUA-cam No1. Fan ok I will take the No2 position after Richard the Great!!
23:46, Seperate fault in the house
The house is haunted buddy, lol
Ghost of "Graham or maybe Fred"
OMG Baz, I'm still having nightmares!!!
The youth in the loft with his farm
It's the Bee Gees Barry Gibb
Always test insulation resistance with the cpc still connected to the earthing arrangement
Thank you for your comment Robert, personally I've never heard of that, what is the reasoning behind that?
Thanks for watching
@@DoctorElectricUA-cam if you look in the regs or gn3 it is the actual way you should do it .
Basically you might have just a screw/nail through the line or neutral conductor only .which would still give you a clear reading when testing against just the cpc conductor disconnected. If you test against the whole earthing arrangement with the cpc connected it will most likely detect this fault as it is testing between the damaged cable and the whole earthing system including bonding . I had one recently where I was getting under 2 meg ohms on a new install when testing against the whole earthing system but the fault would clear when just testing against the cpc . It turned out to be a screw had just nipped the neutral conductor in the kitchen .
Thanks for that, it's not the way I was taught when I was an Apprentice, I've been doing it that way for years, I'm gonna go have a look through GN3 at the weekend.
Great comment, much appreciated 👍👍👍
A fused switch going to a fused plug....yep, kitchen fitter at their finest.
£150 to change 4 x halogens to LED? B & Q sell 8 lamps for £16.
And if you look on eBay you could get 10 for £5 and if you look in a skip you could get 20 for nothing. Cant believe Doctor Electric has the nerve to supply decent down lights and also charges a fee to fit them, its shocking Lester. Hope you're not too upset.
100% Jon
I would never buy 8 lamps for £16, my go to brand is Collingwood, I've never had one fail yet
It's a business Lester, not a charity. Don't fit cheap DIY shit or you'll get called back when they go out in 3 months. B&Q is for handymen
Infinity WTF you sound like a kitchen fitter. I think you mean OFF SCALE High. Telling use you have discovered infinity in a customers house means we need to tell the scientific community of a major breakthrough
😂😂😂, can't beleave ewe evan tuuk tha tyme too right that, BTW I wud liyke too pointe owt a speling mitsake 😂😂😂
@@DoctorElectricUA-cam I’m dyslexic and know that comment makes no sense 😂
Infinity is a correct word when talking about insulation resistance. Analogue IR and continuity testers have the infinity symbol printed on them.
@@adamw225 : 100% spot-on mate.
Mate please keep the swearing down not a video I can watch with my kids with you swearing. Thanks
Thank you for your comment, a few weeks ago we made the decision to do just that, but our older videos still have a bit, thanks for watching
Thanks for your comment Karamat. The ducks 🦆 are now fudges and the pits are now sugars 😉😎👍🏻