Over 30 years ago, I used to calibrate all kinds of equipment as a job. Including clamp meters of course. One thing to call out for both analogue and digital meters is that their most accurate readings are quoted at FSD. ( I.e. full scale deflection- an old term used when looking at the indicator needle on a analogue meter) but due to non linear characteristics of components such as hysteresis loss and other items I will not go into here, it also applies to meters with digital displays. . So if you have a clamp meter and you are using the 200 A range, then it’s manufacturer might quote an accuracy of 1% when measuring 200 A, hence readings around 195 A will be almost as accurate. However, measuring instruments are non linear. Hence if you are measuring a load of 1 amp on the 200 A range, you may have a significant inaccuracy , maybe a 20%-30% error! Or more on an analogue device. E.g. old fashioned AVO 7 meters could be more inaccurate for measurements near the bottom of the scale. So my advice is :- when buying a testing device ( of whatever price range) ensure you get one which has a low milliamp range. This ensures that when measuring leakage current of only a few milliamperes, you are operating as close as possible to the top of the meters range to get best accuracy. If it’s an auto ranging meter, then manually over ride this to select the appropriate range.
Being in my 60s FSD is a term I was brought up on. I've always had the same mentality towards what you rightly say. In fact it's so embedded in me that if I'm cooking something, I often add the ingredients straight into the pan which can weigh say around a kilo. If I place that on the scales, zero it and then add say 100 grams of something, I instinctively think that won't be as accurate a measurement as if I'd weighed it in something much lighter. A slightly different analogy but an indication of how you think about things when you're brought up in with this kind of thing.
@@TheFool2cool That is prpbably just meant to explain that this way, in this case, with this amount of slack on the wires and with this amount of space in the cabinet, you can do it without turning off any circuit breaker. (That might be inconvinient or unwanted in other situations) So in my opinion Martin King made an excellent remark
I use a megger Dcm300 all the time. I use it mainly when looking for diverted neutral currents at the MET when carrying out an annual inspection on a petrol station. Diverted neutral currents can leak from neighbouring properties and through existing TNCS systems on to the petrol filling station and then leak to ground through buried steelwork and pipework in explosive areas such as petrol manholes and tanks. It is now common practice to use TT on all new build petrol stations because of this risk.
Very interesting thank you. Presumably you clamp around the suppliers incoming earth to check for Diverted Neutral currents or TT earth currents? And what would range of AC current would you pass as OK? What do you do if too high? And do you also check for DC current if the petrol station is next to an office building using many computers?
Great video as usual Joe. I was trying to explain this to someone the other day and getting nowhere 😕. I sent them this and we both watched it at the same time. Now not only does he understand what I was saying but he's heard it from someone who knows exactly how to explain things and with much better language than I can hope to grasp. Thank you.
Wow, just stumbled across this comment, must have missed it the first time round. Thanks James, that's really kind of you to say, makes me happy to know it's helping people. 😊
RCBOs which have functional earth connections can be a cause of earth leakage via their earth, which can be an issue if there is another RCD upstream. I measured about 1mA - don't recall which brand.
Great video. This is something no one seems to talk about and also explains how the leakage is measured between live and neutral. I worked for a company that had a vehicle EMC chamber and it had a massive filter on the outside that had a high leakage current. Until the time it was installed I had no idea of permitted leakage currents in the regulations. Also, if my memory serves me correctly it had to be wired back to the fuse board in SWA cable. That was around 15 years ago so my memory might be playing tricks on me. We also couldn't power any equipment with RCD sockets because of the noise they generated.
Great video, really well explained. I'm an electrician in Spain and I've been using a leakage current clamp for about 6 months now and it's been great help. However sometimes you get an RCD tripping due to transient impulses, high frequencies or presence of loads. Then you have to install a "super-immunized" RCD. Not sure if they're allowed under UK electrical code or not.
Hey, I'm in Spain too and I came across this video because my RCD is tripping randomly. How would I know if the RCD I have is super immunized or not? EDIT: Nevermind, I found the symbol. It looks like mine aren't so I will replace them.
An accessory to build is a 13A plugtop to 13A socket with separate L N and E wires between. Then suspect or items that require to be proven good or bad can be tested individually and tested independently.
@@pooley2853basically, just a normal, but very short, around half a metre, extension lead but with the wires exposed so they can be accessed individually.
Doesn't that useful little clamp meter need to be professionally re-calibrated every so often, just like laboratory equipment has to be, or microwave leakage meters?
I’ve had my dcm305e for a little while and it’s already paid for itself in the time saved fault finding nuisance tripping. I would highly recommend buying one
Yes I have one here in France, not a Megger unfortunately, a cheap Chinese thing. Nevertheless it's really helped me in fault finding nuisance tripping and confirming that my install is below the maximum permitted leakage for any given RCD (which in France is 50% of rated trip current, unbelievably. I've never seen a figure anywhere near that on healthy circuits!)
Nice to see such well organised distribution bords. 70% of distribution boards what i meet on site are NH or E27 fuses from 1980's. Wiring there looks like a spaghetti.
What about those 100A blocks splitting tails inside meter box? Last video about EV's installs, you guys said that equipment shouldn't be installed inside there. How to go around those situations?
I don't see how you can use it without rcbo. Your line and neutral wires are usually separated in the electric cabinet when usual mcbs are used. The cable from the appliance usually include earth wire, so loop meter will show 0 .
Megger really need to have removable clamp teeth and add both a hard clamp teeth and a flexible coil to enable you to get easily into difficult to reach places and small spaces with this meter. Second, here in the USA most of the electrical manufacturers are accommodating these issues in the latest electronic and hybrid electronic and hydraulic GFCIs we have them trip much faster and much lower currents around 3-4mA in 3-5 mS. How are they doing this without getting more and more unwanted tripping? Well because the GFCIs are detecting not just the amount of the minuscule DC leakage but they are detecting the whole signal, identifying the various types of surges and transients. Moreover the GFCIs are themselves self testing several times a day. In the UK many RCDs and the regulation does not help here tend to specify at least a 30mA RCDs, or RCBOs at installation time it’s all cost driven and in my view hinders the take up of more latest generation RCDs that trip much faster and much lower leakage currents. Making them much safer than the older generation ones. Efixx should be looking at these issues and really this is going into the the power quality area and I don’t mean power efficiency aspects but real identification of problematic PQ matters. Of course that requires more sophisticated expensive equipment at least if you want to do lots of PQ issues and have accuracy. This is still way too much solely a industrial or solar PV, EV issue. We need more sophisticated and affordable residential PQ meters with good mathematical signal analysis software built in. This will be also important when coming to design electrical circuits and consideration of loads. At some point in the UK you will go to larger boards as you design circuits more with device specific loads on them.
I started using an earth leakage meter a few years ago. I can’t quantify the stress it’s saved me before doing a consumer unit change. If the earth leakage reading is off the scale I don’t even bother quoting for the job. I just explain to the customer that you’ve a pre-existing problem. Not worth the grief or risk of tripping after changing the unit. Well worth the money.
@@johnburns4017 I used to but I’ve formed the opinion that it’s not worth the risk of nuisance tripping coming back on you. Once that starts then you’ve inherited the problem. Got to ask yourself, do you really want that? IMO life’s too short for that and after 31 years of being an electrician I’m aware of the stress that something like that can bring.
Hi Joe, from an old spark from the 60's. I think all your video's are extremely informative and well presented I really enjoy them immensely. I would just like to ask you a question, I own 3 earth leakage clamp meters, I like to do regular global tail checks to ascertain whether any early signs of problems in mine and families homes, I would just like to know what you would be consider unacceptably high main earth current probably emanating from the neighbours or street light leakage, I also do all my own bumbling and always use a bonding lead before I disconnect any joints just in case it's carrying return currents, be interesting to what you consider too high main earth current before investigation further. Peter.
Hi Peter, great question. This is a really interesting and deep subject which is a bit tricky for a comment here. Please stay tuned for future content on this matter. Thanks for commenting. 👍
@@efixx Thank you for the feed back, I look forward to your future video's. It is a very interesting subject, and I think high mains earth currents will escalate with the with the massive demands for EV charging resulting possible more neutral faults in TNCS systems, something the power demands was never envisaged when installed years ago. Peter.
In my experience old heating elements in stuff like electric showers and cookers can also leak current to earth, which gradually increases with age as the insulation continues to break down, all the more reason to use individual RCBOs instead of older split load type protection. And some cheap tatty new elements even have rather poor insulation which can cause earth current leakage and nuisance tripping.
I got called to a house where the owner said your the 3rd electrician I have called to for this intermiittant RCD tripping. So I checked and found nothing obvious then I started to ask the question what were you doing at the time. The reply was the ironing but rcd did not trip all the time I used it . Checked the iron and found the cable all frayed and after a few more questions I pinned it down to the oven and iron being on at the same time. Oven was leaking 20mA and the iron was 22mA
Use my megger leakage tester all the time. Had a problem with a large office block that had extremely poor loading of sockets for the computers. Made a Earth cable out extension lead and plugged in everything eventually it was a laptop charger causing the leakage current. With out this I don’t think I would of found the fault.
I don't see how you can use it without rcbo. Your line and neutral wires are usually separated in the electric cabinet when usual mcbs are used. The cable from the appliance usually include earth wire, so loop meter will show 0 .
@@eugeneeugene3313 my explanation wasn’t great. I made a single socket with a plug on the end. In the middle of the cable I opened up the flex to expose the inner cables. Pulled the cpc out of the way leaving only line and neutral in the flex for about 6 inches. Put clamp meter around the line and neutral. Plug appliance in to socket and plug in to a power outlet.
@@Beariam24 Thank you - good trick. If I understand correctly, you actually build an extension cord so that line and neutral wires are not bundled together with earth (ground) wire. So you can encircle with tester loop just the line (live) and natural wire while connecting the appliance via this "exposed" extension cord. Is it correct?
why not just keep the clamp round the tails and turn on the rcbos 1 by 1? saves messing about with the smaller connections, risk of pulling them out etc
There's nothing special about that meter other than how it's badged and marketed. Any clamp multi-meter with an appropriate AC current range would do. The subtraction between the live and neutral currents is being done for you by physics - the difference in the current induced in the clamp by the opposing magnetic fields from the two conductors.
Brand snobbery is rife with the willy wavers! Nick Bundy has started doing performance comparisons of branded kit with unbranded and found little meaningful difference. I’m not talking about your MFT, but certainly current clamps, stud finders, etc. where the underlying physics is simple.
Interesting video. Looks easy when checking RCBO's as the Line and Neutral are close together. I would be interested to see how an old fuseboard is tested. I see a comment suggesting clamping the tails and turning on/off circuits, would this be a better way to check old fuseboards before installing a replacement?? Thanks
Extend the neutral conductors from each circuit within the fuseboard creating a loop and reconnect. long winded but correct reading can be taken between L/N. Or, find the L/N elsewhere on the circuit but you have probably worked it out by now as I'm 2 years in the future.
Pretty essential on both electrical power showers and immersion heaters. I had VERY bad leakage from our immersion heater which did NOT trip the RCD but using the back of my hand on the shower wall, the shower fittings and the aluminium frame of the shower door, I could feel the tingle of mains!! Isolated the immersion heater ... Problem gone. Turned out the element was VERY badly corroded and I suspect that water had entered and gone through the porous ceramic insulation on the heating coil!! Didn't have a clamp meter at the time but I do now.
Very much doubt you felt the tingle of the mains, possibly the pressure of the water running through the pipe if anything. Best way to fault find is testing for insulation resistance using the megger
@@marlonwaites3718 not "through" but "off" the wall! Granted, only near the shower head pipework & thermostat. ONLY there was nothing when the immersion was isolated. Shower was power shower NOT electric so not from the shower and not from the pump ... Impossible from the latter due to plastic fittings and impeller housing. It shouldn't be that surprising, lightning voltage gradient is effectively spherical in its scope, passing through anything remotely conductive ... i.e. brickwork and tiles. So mains can do the exact same thing. In addition i checked the copper hot tank and its surface was live! Tested with an old school neon screwdriver! Tank bonding was renewed too afterwards ... May have been the main problem I guess since the RCD didn't trip.
Efixx doing a great job trying the get new innovations in front of UK electricians. However take up of these is incredibly slow in the UK, partly it’s cost driven but let’s hope manufacturers also realize the potential for better pricing to get into the market as a first mover.
Useful but ugly color + ugly backlight color - and with the only argument that green is the color to witch our eyes are the most sensitive…. I Will always like an yellow-orange backlight …. + it’s expensive 😅 450-500E list price ….
Superb content very well demonstrated. I have owned and used clamp meters for many years as an electrical technician, I usually buy high quality meters that can accurately measure both AC & DC currents because I work on DC circuits in CBU's and vehicles, which makes life easier when looking for parasitical drains and figuring out expected autonomy times etc. If you are in the fault finding game you should have a clamp meter in your arsenal guys.
Great video again 👍 I don't use my EL Clamp meter alot as we don't undertake alot of fault finding but when I have needed it, what a bit of kit. An essential bit of kit for certain scenarios, will always carry one on the van .
What jumped out at me, was no more than *eight* sockets to a circuit to eliminate RCD/RCBO nuisance tripping. That means a lot of radials in a house, with maybe one final ring circuit in the kitchen. So bigger CUs. Having all circuits on RCBOs will reduce the earth leakage tripping problem, increasing the number of sockets on a final ring circuit. Multiple circuits on one RCD can be a big problem as the earth leakage on each circuit builds up to over the rating of the RCD. As mentioned all is fine, it is just that too many circuits are off one RCD. We need lower priced RCDs with none of those pesky earth flyleads.
The rule of thumb of 8 sockets per circuit is for application to commercial installations where a lot of IT equipment is connected, not domestic where a relatively small amount is connected. 👍
Get a short single socket extension open it and run an earth wire on the outside of the flex. Take your clamp meter and now you can quickly change plug and appliance to check which one is faulty.
Sorry for my weird question, but from 2:18 you mention that IT equipment often leaks current to earth, but as far as I know, all laptops, Flat/LED-/SmartTVs, Hi-Fi systems etc. are Class II - double insulated - appliances that are not grounded - they have a plastic earth pin, with no connection to leak current to. What might I be misunderstanding here?
No it's a good question, some stuff is double insulated with no earth connection, but some do have an earth connection, my laptop power supply for example does.
@@efixx Hmmm, that's weird. Here in the fringes of the Eastern Bloc, we only have ungrounded laptops (PCs are grounded though). I wonder whether Western Europe has higher earth leakage in general, which would mean that on the other end of the spectrum, in Mother Russia - where you often can't see a grounded socket for hundreds of miles around - it should be the lowest, right? Or would they make up for the lack of bonding with earth leakage directly through grounding rods?
EMC, the normal definition of the acronym is ElectroMagnetic Compatibility, not ElectroMagnetic Contamination. It isn't just about contamination of the device which would be received radiation, it is also about the emission of electromagnetic radiation from the device.
So this is not a usual clamp meter , its specific to earth leakage Milliamp testing? My second question is you gotta clamp this particular meter to both live and neutral , Lastly what are acceptable and not acceptable readings? I like this device
We on a new development building, and we have a new tv. It keeps going off and on. Sometimes whi but a light on it goes off and on. Not all the times. We thought it was the tv faulty , so we had another new tv ,and it's the same. I'm not a electrician, watched this video, could that be the problem. Phil
I've put my clamp meter around the main earth cable at a few different commercial premises and some of them show 7 amps passing through. What is going on there?
@@muzikman2008 I'm currently trying to fault-find T&E installed in plastic conduit inside a garden wall (i.e. subject to moisture). The line is connected to an RCBO in a covered area (shed) and that CU is connected to an MCB in another CU downstream. Your comment about moisture has now got me thinking. May need to do an insulation resistance test...
thanks very much for your video, very instructive , but i want to know the price of an earth leakage clamp meter and where to get because i am in Ghana and i use to follow your visit
Great video but can you also tell me if such a clamp meter can be used on a mains lead eg a toaster or other appliance to check by appliance what is generating high earth leaks?
If in the scenario demonstrated your leakage load was tripping how would you fix it if you only have one RCD and the device is operating safely and as designed just an accumulated leakage? What options do I have.
A simple ramp test can give a perfectly good indication of leakage also. This for me would only be useful for consumer unit swaps where there is no existing rcd protection.
At what mA value is natural ELC is excessive? About 5 years ago I installed a new 7kw cooker hob which was putting out 6mA of ELC. Along with a number of other new kitchen appliances all putting out 2mA of ELC each the 30mA RCD was tripping a couple of times a day. I rang the manufacturers about it, they said it was within tolerances. I also rang the NICEIC technical & they could not tell me how much ELC is excessive. I had rearrange all the circuits in the dual RCD board to even up the ELC in the 2 RCDs. Since then I only install RCBO boards. But today I got called out to a job with a tripping RCD & found another cooker hob (only 2 months old) putting out 10.5mA of ELC, surely this appliance is faulty?
Hi eFIXX, you videos are great! I have a question and it may sound dumb. Can I use a Current Clamp Meter as Leakage Clamp Meter? Are they built the same way? I often see the electrician using the same clamp meter to measure both the current and leakage. Look forward to receiving your reply!
Not qualified sparks…but could have been considered time served. I recently changed an MCB to allow for motor starts in my garage not causing it to trip. Are there different types of RCD that could allow such laptop leakages without tripping but without putting users at any greater risk of electrocution should someone get silly with a wet finger?
Not really, you could in theory put in an RCD with a higher mA rating but then it wouldn't comply with the requirements for additional protection. 🤔 In fairness you'd need a lot of laptops to trip out a 30mA RCD anyway unless one was faulty.
Often it's the cumulative effect that is the problem. A 30mA RCD could trip at 20mA and if you have a ring with many loads it's not difficult to get to that. Split it into two radial circuits and use 2 off 20A MCBs , one either side off each of the 2RCDs
Interesting video. So your PC is leaking while it isn't turned on? Is that fully off or standby? Since you unplug the cable, I assume it was off while it was leaking the 0,6mA. Slightly related question. My macbook is okay when powered on battery, but when I use the extension to 220v, the metal casing of the Mac starts to have static load.. tingling feel when I slide my fingers over the surface. Mac extension cables don't have earth. I assume this would have been solved if Mac's would use earthing? (I've had this with every other Macbook before as well, not just the current one)
Many clamp meters are integrated into multi meters (have not seen earth leakage clamps in multimeters yet, maybe someone can inform us). Screwfix sell a decent LAP version for around £30. I used one of these, with it being quite good. The problem with the cheaper products with some of them, is not with the instrument, but cheap leads. Buy quality leads and use them, then they seem OK. But the initial cheap attractive price is then hyped.
Difference between a clamp meter and an earth leakage tester though, a lot more sensitivity, I’m training as an EST, got asked to follow an electrician regarding a tripping RCD, my fluke 902 lacks the sensitivity to see if the tripping is due to the earth leakage, all I can say is the appliance will run without the house plugged in, but plugging in the house alone will be fine too.. they just can’t be on together… they either get hot water, or lights…the house is like a permanent caravan, connected via a caravan plug to the RCD within the main house…
I work in events providing large modular LED screens to events and gigs. We can have over 200 switch mode psu’s on a screen (1 per cabinet), each dumping their little bit of current to earth. We have to factor in the number of cabinets per RCBO and can end up with 48 or 72 channels running to the screen over socapex multi pin connectors and cables fed from 125a or 250a three phase supplies. Nuisance tripping isn’t wanted when you could loose the screen behind the headline artist….
Iv'e had an Amecal low current clamp meter for about 4 years, very usefull for tracing earth leakage ... mainly washing machines, ovens, and water heaters i find faults on. great video.
Exactly - not IT equipment. The "No more than nine IT devices on a ring" is an old-wives tale in a modern house. If you have a mainframe, then we can talk about ELC. Cookers are some of the worst. Especially when some jobbing sparky has attached the live and neutral backwards because "Hey. It's AC so it does not matter." - I hear this comment from too many sparkys!
This would have been handy in I think 2017 or 2018. I had a meter at that time I don't know if it had the scale that I needed. I was working on a film and doing data management data wrinkling. I pulled up in my van set up and ran 100 foot cord to an RV and older RV. That RV then plugged into an RV socket. After a day or two of doing this I tripped the rcd (we call them GFCI's or GFI for short) and I had to track it down in the RV to an outlet buried somewhere I think it was either by the electrical panel or sink. All the outlets or on this one circuit it was an older RV and an older GFCI. After finding that I ran 200 feet of extension cord to the only other outlet other than the one running the coffee maker ( an extremely important appliance unless you drink tea like I do but I didn't wanna get out anybody's bedside either). Would've loved to known whether that GFCI was just getting faulty with age and cranky with the long cable run or maybe I got some moisture in one of the junctions I don't know. I just know I had to get the production management trailer back on line before I could do anything else as that was essential and the only place with outlets are than the one under the coffee maker outside and the one other dedicated outlet I found. See the biggest problem is we test the functionality occasionally and we're supposed to test monthly according to the instructions the manuals and documentation and even printed on the devices but that doesn't happen and that's just a functionality test. I'm sure more industrial like places might have the money to put forth into higher test requirements but generally homes and businesses as long as it's working, it's done right and meets code.
Question for you guys, I’m a sparky & had an interesting conversation with a wholesaler today about electric vehicles. According to the rep different manufacturers use there own plugs on there vehicles, now I assumed ( apparently wrong) the there was an industry standard plug?
