When I began watching, I thought this might be pure product placement as you'd been sent the product. I was wrong. A really informative and easy to understand explanation. Thank you!
As a electrician I'll always recommend watching your videos. I often get questions about how stuff works from friends and customers and gladly show them one of your videos and here is why: 1. I trust your competence and know that you'll have a good explanation and 2. the customer will shut up, let me do my work and not ask every 2 seconds. You are and always have been such a big inspiration in my life and i am glad / thankful i was lucky enough to stumble across your channel. Thank you!
Thats one thing ive allways liked about you clive, you boil things down to the basic info for learning :-), ive never dug into rcd's but it all makes perfect sense now :-D My distribution box has breakers, then two earth leakage boxes with twisty reset knobs and test buttons, sockets = 1, lights = 1. They trigger at 30mA
At the school I used to work at we were given a bucket load of old Fluke clamp meters. Our Cambridge educated head of physics a Phd no less, tested them by putting them round the kettle lead and declared them all broken... So we got given them for the technology department to play with. They all worked fine.
neg he clamped it around both line and neutral. Need to clamp around either the hot/line wire or the return/neutral wire to measure the current. If he went around simply the whip/cord of the kettle then he was clamping around both live and natural and you will not get a reading.
I've learned so much from the videos on your channel. I have been a diy electrician for a good 13 years now in the US and all of your information is invaluable! Keep making these videos for us Clive!
Nice to hear Canada isn't the only country with standards boards that invent overly complicated solutions/tests for relatively simple problems. Enjoy your videos Clive, always a good show. Cheers!
I'm happy to see the big fella mentioned the accumulative leakage scenario. I started realising this when we first starting install the dreaded safety switch as they were know then. Now I just use the single module individual RCD on each circuit to mitigate that very issue as we don't use ring circuits in Australia Thanks for the content 👍
I've been using my amprobe for this application for years, well before it was fashionable. Don't put your earths in the same sleeving though when I come to test that short piece of cable I will need to separate them for ring circuit continuity! Well presented video Clive. Well done!
+mikeselectricstuff That could trick you tho, because there could be just a few milliamps on many breaker circuits. Might aswell just whip out the megger if you're going to trip breakers.
+Vegard S. Right, but if you have a suspect circuit, and you kill all the others, that would give you the result. He meant if the ring is inaccessible..
That was utterly brilliant, thank you. Explained everything I had failed to understand from all the other videos I have watched, a bit like when I was at college and a plumber finally managed to get me to understand applied mathematics, when a lot of other people MSC's , PHD's had failed. Some people can teach so you can understand and some cannot. You can, thank you. I am suffering a nuisance RCD trip out, that is getting worse. I suspect an old RCD and an old fridge, but it could be something else. I like to do my own trouble shooting before I call in the experts and your video has shown me what I need and what I need to do before I call in an electrician to fix the problem. My Dad, taught me just about everything you shouldn't do with electrical equipment; he was a sales manager for Black & Decker so we had lots of tools lying around without plugs both 24v & 110v. Whilst I always made sure that everything I used at least had the earth wire wrapped round the earth pin of the plug I was using, something I know he failed to do on at least two occasions, but lived to tell the tale, I made sure those lessons were never passed on to my sons LOL. It's just what painters do made me laugh. I spent over 40 years in the construction industry a lot of it in refurbishment.
This is the best explanation of how a rcd works and how to test appliances and circuits. Ring main sounds like a fire hazard. I'm from Australia and we use 2.5mm2 for power with a 16amp breaker. love your videos. keep up the good work
About the most useful gadget I bought is the Habotest Socket Tester,very easy to use,and which indicates several faults. I pressed the RCD button to see what would happen,and the whole circuit cut out immediately. I habitually check every socket outlet to ensure its functionality. I have a clamp meter which I have not used yet,usually finding the multimeter adequate for my needs. Very glad to see this video,because earthing has always been a "thing" with me.
Hi Clive, I think the max button is essential for RCD testing. Without it, and assuming there is a fault, as soon as you turn on or plug in the faulty device it would trip the RCD and you wouldn't know the scope of the current (32mA or 432mA) - unless the meter has a max feature.
This was a great explanation of the RCD/GFI (or GFCI) system. Would love to see a video on the newer Arc Fault breakers. They're code in the US now for bedrooms and designed to detect faults between live and neutral.
+sparkplug1018 I've asked the same thing. I read about 'parallel arc fault' and 'series arc fault' detection on AFCI's. I *definitely* wonder if the 230v is able to 'flash over' more effectively, essentially allowing more fault-current flow (allowing normal MCB to be good-enough for parallel-arc-faults), where 110v might tend to sustaion a more 'resistive' arc or something weird like that........
At the moment AFDDs as they are called in the UK aren't mandatory and I was recently looking up the prices of consumer units, and I made an interesting discovery This is how much it would cost to purchase each type of consumer unit in the UK, not including installation costs Dual RCD, 6 Circuits: £59.99 / €69.27 / $83.72 RCBO, 6 Circuits: £109.99 / €127.02 / $153.52 AFDD, 6 Circuits I am unable to find a pre-populated Consumer unit for this configuration, but the following is based on an unpopulated consumer unit plus 6 AFDDs: £857.69 / €990.59 / $1197.10 RCBO is an RCD combined with an MCB AFDD is Arc fault detection combined with an RCBO
Hi Clive. I tend to design my circuits around radials now rather than ring circuits. If you need a load up to 32A use 4mm2 obviously taking into account installation methods etc. Another great vid. I have one of the clamp meters, had it for years and occasionally it comes in useful for fault finding. Most times a ramp test off load for the RCD will suffice. I like the idea of the test rig. Will make one this weekend.👍🏻
as an electrician I have found surge suppression devices such as a four gang short extention lead are prone to coursing nuisance tripping. often if the device is on the way out I have found that the variation in supply voltage can make the difference between them making the RCD tripping and putting it on the edge. I have also found high inductive loads such as the vacuum cleaner mostly double insulated can be enough to put a spike into the supply to make a trip go were another fault exists nothing to do with the vacuum cleaner. as for ring mains I absolutely hate them as the testing and fault finding is a nightmare.
+christastic100 Yes! Exactly.... Seen similar with spikes to earth from iffy electric drill, creating similar effects, tripping a "different" RCD to that its' attached to, which has a lot of supression-to-earth stuff plugged into it, probably because of loose earth currents/spikes, going (imbalanced) into L/N of the circuits with the supressors attached... Nice solid earthing, combined with Individual-RCBO consumer units much preferred to minimize these nuisances!!!
Hi, with regards to the non-faulty double insulated vacuum cleaner tripping the RCD when combined an other fault that exists. That other fault could be a Neutral-Earth insulation resistance problem on a final circuit... Imagine that a socket outlet was refixed in a hurry, and the insulation on the neutral conductor became slightly nicked on the earthed metal back box. Under no load conditions, the neutral has basically no current flowing in it. However, when you use said double insulated appliance, the current flowing through the neutral (within in the final circuit), is now shared with the earth conductor (CPC). Thereby, producing an imbalance in the current flowing within the live and neutral conductors inside the RCD, which if great enough (dependent upon the compression fault, i.e. the nick in the damaged neutral cable, which will also deteriorate over time), could cause the RCD to trip. PS. I’ve seen this first hand a few times as a maintenance electrician, so I thought that I’d mention it here.
Why would two RCDs in series trip together, after around 24 hours powered? But when there was only one RCD it did not trip! I didn't find a large current imbalance nor any ground currents. Any tips? Do you think it could be a marginal MOV, and a voltage spike? Could a large UPS cause this?
I work for one of the electricity suppliers/DNO's and we upgrade the incoming mains, cableheads/cutouts and metering in houses and flats, mostly for council and local housing authoritities. There has been a trend towards some of these organisations rewiring their houses, and because they are complying with 17th edition regs, all circuits are rcd protected, either dual boards with two rcd main switches with individual circuit mcb's, or with individual rcbo's for every circuit. This is all exactly as expected, the problem occurs when these houses have electric heating, usually off-peak storage. Some councils now think they can get away without fitting any equipotential bonding, as they say everything is rcd protected, so no shock risk, therefore bonding is not required. This might be true, if they were replacing the heating consumer units, but in most cases, they are not. Some heating boards are being left, some still only protecting circuits with old rewirable fuses, so the cables are protected from overcurrent and short circuit, but without bonding and EEBADS, there is no shock protection. People like myself, and the companies we work for, have raised this with councils, but they are not all that interested.
+ben kerr virtually impossible to protect against electric shock in all possible cases though. You won't trip an RCD/RCBO when dropping a two-wire appliance in a bucket of water, for example. I guess they don't care about bonding everything when there is no Freezer-only socket, though (considering that some people would still plug in a vacuum cleaner in that socket given a chance).
+ben kerr I've caught the same attitude from electricians "doesn't need bonding, it's all on an RCD". That attitude winds me up no end, I think the 17th edition's requirement for RCDs on everything is a mistake.
Interesting comment. Most cable jointers / linesmen don't know anything about domestic electrics! Yes you are correct but the Electrical industry or the attitude to inspection reports, compliance etc by housing associations and agents etc is a joke just want a piece of paper. I used to get upset about all the non compliances and how blasé people are about it...... I have given up..... They just think you are a jobs worth
Great video! Thanks! It took me a couple of hours to find a N-E fault on one of my ring mains. Which was then down-rated to 20A radial as that fault was unusable (and not wanting everything re-chased out). I'm a DIYer but did it in discussion with my electrician.
Timely advise! Thank you Big Clive. I have some troubleshooting to do around the house and your explanation will help me track down the faults immensely. Unfortunately, that nice little meter has a $50 shipping fee to the U.S. I can find other clamp meters at the local big box hardware stores, but now I know a feature to look for, and have an inkling of how to use it. Thanks again! Thanks for the insight on a test cable too! Looks like I'm going to have a few tasks ahead during the holidays. Such fun! (no pun intended)
So far I've been having trouble finding anything with a range less than 2 amps, plus it seems the lower end ones are only AC rated. Will an AC current clamp meter measure DC current? ~I worked as an electronics tech repairing military grade electronics for twenty years (software engineer now), yet I feel like a complete novice asking a question like that.~ Also, if I might change the topic slightly, is 120VAC @ 2A more or less dangerous than 120VDC @ 2A? (Another 'novice' question...so embarrassing!) The reason I ask is because it seems that some LED drivers come in DC voltages well above 120 VDC, though current limited to specific currents, such as 1400 mA. That allows you to series up to 4 high power (50W) LEDs, which simplifies certain LED configurations schematically, but it seems to me that you trade off safety for simplicity.
+PaulyG10657 Sadly an AC clamp meter will not measure DC current. The AC ones usually use a coil to detect the magnetic field, while the DC ones use a solid state hall effect sensor. AC is generally considered more hazardous than DC because it causes continuous stimulation of the muscles. But even DC supplies can give a nasty buzz if there is residual mains derived ripple on the output.
Thank you Big Clive. In either case, AC or DC, whenever I work with 'mains' electricity I always do so with an over abundance of caution. If I'm working on low voltage low power battery circuits I'm a bit less paranoid, of course.
DC is worse IMHO as it leaves the muscles no chance to relax leaving a vice like grip on a conductor, it does not take AC to continually stimulate muscles.
This remindes me of a very interesting story our teaxher told us. Basically he was at a friends house to help with some electricals problems that caused the rcd to switch off when he used his microwave, but only when the lights in the basement where on at the same time. I have to say that I live in germany and some of the old houses here that were wired in the 80s still have 1A RCDs. it turned out that the wiring for the lights was faulty because the lamps where connected to ground instead of neutral. Do when the lights where on there was a current to ground at a bit above 900mA wich worked fine. But once the microwave was turned on, the additional small leakage current of the microwave was enough to trigger the RCD.
+jpalm32 I'm not sure if Arc Fault Circuit Interrupters are required in the UK like they are in the US for bedroom circuits and such. Just so our UK readers know, Arc Fault Circuit Interrupters are designed to detect non-working arcs in faulty wire connections, and broken solid core NM cable (Romex, twin and earth). The AFCI's use sophisticated signal processing techniques to discriminate between a working arc (say from vacuum cleaner motor brushes) and arcs caused by poor connections and faulty wiring.
at the time I am writing this comment, arc fault detection is currently only "recommended", not "mandatory", in the UK and it was only a year or two ago when the UK regulations even started to mention them, and so as a result until they started to be mentioned they were pretty much non-existent in the UK, and although they are now available here, to fit an entire consumer unit with them could easily cost over £1000 (and a basic dual RCD consumer unit may cost as little as £350 to get it installed, and most people in the UK tend to go with the cheapest option, so unless the regulations change from "recommended" to "mandatory", then I cannot see them being fitted in mass, and even if the regulations did change, unless the prices came down, chances are, as most people wouldn't be able to afford them, then they wouldn't get fitted as often, and also, the regulations are not actually law in the UK)
Clive, I had never heard of a "ring main" circuit before and had definitely never encountered them here in the U.S. Seems to me they'd be potentially rather dangerous. As you said, the wire isn't rated for the total allowable current on the circuit. This isn't a problem as long as you have both paths intact to divide the current load across. But if one leg gets broken, you have, as you'd put it, a bit of a dodgy situation. The breaker allows current to flow up to the 32A limit but with only one leg of the loop supplying potentially all the outlets, you could easily exceed the safe capacity of the wire. Seems like a recipe for fires to me.
TBH, I dont get many RCD's that fail due to oversensitivy, but you'd be suprised how many I get that dont trip at all, pressing the 'Test' button is a requirement at testing, most homeowners have never pressed it, a simple thing to check a device that could well save your life. For the record, Im not a fan of Ring finals neither (Not ring mains :P) Love your channel, a recent subscriber but believe me, im working through em. Cheers L.
Fascinating look at your circular circuits. We don't have them in the US but in the mid 1960's, it was popular for the Bell Telephone installers to prewire telephone cable in a house in that manner. The idea was if a wire broke somewhere through the house the phone circuit could still work its way around the other way. Much of that cable was like 24 gauge and could break easily.
+CowboyFrankHarrell We have radial circuits too. In fact a few years back there was talk of them making a comeback. But in order to have the same kind of load as a 32A ring they have to be run in 4mm² cable, which is a bit of a fight to work with in a tight space like a 32mm deep socket back box. The 2.5mm² cable ring mains are run in is a lot easier to use even though you have to deal with two cables at each outlet. Also if you want to add a single outlet to a ring you don’t necessarily have to break the into it - you connect it to the ring as an unfused ‘spur’ using a single 2.5mm² cable.
Hi Clive, I've had real issues with this particular meter and an even worse response from the company. I've tried allsorts of different scenarios and positions etc but Im just not getting the results I expect. In fact some of the results in the 200mA range far exceed the mA trip threshold of the RCD - and thats when testing it on a type A rcd. Ive also tested on type AC and the readings are all over the place. I contacted AMEcal who exchanged the meter after saying it was faulty - however the one they’ve sent ‘calibrated’ is exactly the same results. It took several months to get a reply from the director who then said testing the line and neutral together was not how you do it. After showing him the instructions in the book that comes with it he told me to xxxx off as I didn’t know what I was doing. Then I called straight back and got hold of the ‘test engineer’ who clarified the ones he tested also gives very erratic and unstable readings. All I wanted to do was put the meter around the line and neutral to measure the inbalance / leakage to earth. It even measured leakage with the cpc/ earth removed.
only 32 amps? thats like 7680 watts? not sure in the states but in Canada we get 120V at 100 amps, we do not use GFIs/RCDs at all, it's all breakers. the only place you see GFIs/RCDs is in places with sinks where an electrical GFI outlet plug controls the lights and other plugs.
There is a curseword in German for painters, who are messing with your electrical installation... I learned it during cleaning german earth connectors in walloutlets... "Pinselquäler" which literally translates to person who tortures brushes. Maybe this anecdote brings as much smile to your face as your amazing "it certainly wouldn't feel like you are a lightbulb" brought to mine.
Rogue trippin' sounds like something interesting to explore. Could it include mushrooms? ;) Edit: Really nice explanation of the inner workings of a GFI/RCD, best I've watched. Thanks Clive! :)
Rings are genius, they used to only fit 4 way wylex fuse boards (were talking 50 years ago). 1 way for the cooker, 1 for the lights, 1 for the immersion and 1 for the power - the ring main. This would be on a 30A rewireable fuse, so they would run a whole houses worth of 13a outlets on 1 circuit. Back in the day the standard was 1 outlet per room so this method worked well. Now everyone wants 4 or more per room so we are mainly fitting multiple radials per house/flat, and a ring in the kitchen and utility room
I'm not an electrician so obviously I'd never work on the electrical system in the house, but when I am working on the electrical system in my house I always turn off all the breakers. Because I know I haven't got all of the proper insulated tools and all of the safety training, and sometimes there's a circuit where it's not supposed to be, so it's just safer that way.
When I saw that meter mentioned in the description I had a look around for it, but at this point in time (and for the forseeable future) I don't see me doing enough electrical work to justify the expense -- it IS a bit spendy. I have on hand here a short extension cord with one of those devices inline. The test button does nothing, so I figured that it wasn't working. Thanks to your explanation of how these things work, I might have to "take it to bits" and see what I can find out about why. :-)
I run a small electrical repair business and find the top trippers are 1. Kettle 2. Toaster 3. Oven 4. Hob The other issue is small leakage so 2 or 3 appliances on at the same time can cause a trip and harder to find. Last on was a oven and iron used at the same time
I made an AC Line Splitter that is connected inline with, but after, an RCD. With a male and female plug and socket on either end. To be used after the power point and before the load. I.E. Socket-Plug-Lead-RCD-Lead-Active, Neutral, Earth Split-Lead-Plug-Load. It saves having to break the line of the load. And is meant to be used with a clamp meter when the load is too far from a power point and you can't see the power meter screen at the outlet. And you can measure the inrush on the load. And I double insulated everything with heat shrink and glueline breakouts to split the line.
Nice bit of kit (I want one). I worked as an electrician in France for 10 years and got a LOT of critical comments (from the French) on the UK's use of the ring main. A LOT of Brits were coming over and wiring there house UK style. NOT legal here. I had to rewire a number of houses when this was discovered! Still, it kept me in work. :) Keep up the great videos please.
+Eric Gee That would be easy enough. Disconnect ring in middle and turn into two radials, each on their own breaker. I worked in France for a while too. Some other strange regulations. At the time they stopped me wearing a harness in a cherry picker because it was believed it was safer if it started to tip, to grab something and let it go down on its own without you being dragged to your death behind it.
+bigclivedotcom It's not that easy, because here (France), Black can, and often is Live. You could separate the loops and remark(Blue tape) the black wires, but they banned "Twin & Earth" as the Earth wire must be fully insulated here! On the plus side it's warm here (I'm from Sunderland) and the wine and cheese are cheap! Merry Christmas Clive. After saying all that, perhaps "Twin & Earth" is no longer Black & Red!
+Eric Gee The cheese and wine aren't just cheap in France. They are vastly superior to the stuff here. Sadly our wiring colours have been unified with Europe. Twin and earth is now blue and brown. But in the process they changed our vivid phase colours to bland ones. and swapped a phase and neutral colour, which still continues to cause significant electrical accidents.
+Eric Gee I don't like the L2 phase being black in Europe, it is identical to negative of DC circuits. I do however prefer the new scheme with brown to L1, (black to L2) and grey to L3 rather than the old UK scheme. I would have preferred having L2 purple or any other colour except yellow, red, green, blue or black (to avoid confusion)
Great explanation, Clive. One of the 2 RCDs on my consumer unit is tripping out very intermittently so I bought this tester and it is indicating leakage on a number of circuits. The highest reading is on the cooker circuit (100mA+). As the RCD is only rated at 30mA does that mean the cooker needs replacing?
+Chris Hale That is a lot of leakage, but I would have expected the RCD to trip all the time at that leakage. Is the RCD definitely 30mA? You can do an overall test if you can get a clamp meter round the live and neutral meter tails if they're accessible, then switch circuits on individually to see the differential.
I've checked the RCD and this is definitely marked 30mA (MK RCD model 7860s). With the meter clamped around live and neutral meter tails there's an 'ambient' reading of 20mA. Switching all other circuits off except for the cooker the reading drops to 6mA. With both ovens plus hotplates switched on the meter reads 200+mA, but the RCD doesn't trip.
Did some further diagnosis today and found that when I switch off the mains isolator for the consumer unit I can still see a 200mA+ meter reading when I clamp it around the earth wire. Looks like this could be an issue with the earthing of the mains gas pipe because when I disconnect the earth bond to the gas pipe the meter shows zero current. Any ideas on what might be causing this current to flow to earth when the bond to the gas pipe is in place?
The last time I took apart an RCD I found some interesting mechanism for the test button that would be worth a video: Instead of closing some connection there was an inductor wired into the line and the test button would lower a metal tab onto the core of it, closing some short through the inductor, massively changing its inductance and thus causing a short imbalance in current flow
+Cashpot Say RCD "trip switch" is confusing term... Because extra 3mA not enough to trip the "30mA" RCD (which normally takes about 20-25mA typically).
Is there a requirement for RCD protection in the UK now, particularly on lightning circuits? I entered a saturated, humid room (hot tap left on) in a building and got a shock off the light switch before I realised the room was damaged and the switch wet. Should that have triggered the RCD? Because it certainly didn't.
I had some really weird tripping because of the street cars(tram)They had big stray currents that found the earth pins of home owners.Really weird problem,but when we tested it soon became clear the thing tripped when a streetcar was pulling from a stop.
Hi Clive. Interesting video, i was not aware that UK installations was different from the ones in Denamrk, with breakers rated at 32 Amps and loop installation, and i am an elctrician my self :-D In Denmark the Ground fault interupter breaks at 3mA (By law, since 1975), and the lighting groups is rated at 10 Amps, with 1,5 mm2 cabels, with no loop. Also in Denmark, usually there is one 3 fase group, with 3 x 16 Amp fuses, 2,5 mm2 cables, in each household. Love your videos, keep up the good work. Thank you and happy Christmass, from Denmark.
+Morten Rolsing I think the odd "ring mains" thing are to the UK as "wire nuts" are to the US (well, wire nuts, split phase, open carry, the list goes on). Australia has similar wiring conventions: 10A for lighting, 16A over 2.5mm2 for power points, although you're allowed a 20A breaker if the cable isn't covered by insulation. 3 phase is typically available in residential areas, but not commonly connected (only a single phase mostly), except for specific loads like a big-arsed aircon.
Lots of reasons for ring mains, including a) greater current handling, b) reduced cost at distribution board, c) even heating effect (especially in conduit), greater cable flexibility. Not saying that the pros outweigh the cons, but just saying those were the reasons. BTW, current drawn through the circuit doesn't vary according to where it is measured (which I'm sure you knew). Love the videos though
Very well done... was expecting the Amecal would be taken to bits before the end of the video!! ;) Clive, do you have experience with Arc-fault breakers in the UK? These are now recommended for additional safety in homes with 12/2 aluminum wire branch circuits (typically homes built in North America between 1968 and 1977), when copper became very expensive. While the wires themselves are perfectly safe, aluminum is absolutely intolerant of poor installation workmanship. Wires being nicked, terminals not being tightened to the correct torque, being in contact with incompatible alloys resulting in oxidation, cold creep etc. Which all lead to overheating connections, and ultimately fires. I found it interesting, an arc fault breaker has been designed which can detect this, and disconnect the circuit quickly, just like a RCD/GFI does with ground leakage.
i lived in one of those houses as a child. Fortunately, my father smelled the burning electrical insulation *through the wall* before the house caught on fire. i did some armchair research on it, and i agree with you. the only thing i'd like to add is that homes have hundreds of electrical connections, most of which are near flammable materials and almost none of them can be inspected easily. AND, in the early to mid 70's, the construction trade did not fully understand just how fussy aluminum wiring is. these factors combined practically guarantees a bad connection somewhere.
+PuchMaxi1988 Yes, because the ring main is rated for 32A but most appliance leads are only rated for 5A or 13A, you need a fuse to protect the appliance lead if a fault in the appliance tries to draw, say 20A through the appliance lead.
+MrOpenGL Surely not the ONLY reason. As we could just as well still have 32A circuits just using a higher grade wire, the appliance cables would still need protecting.
Alex Atkin But AFAIK it's the only reason to have fuses in the PLUG, not in the appliance. In any appliance, the fuse is either internal or is on the appliance itself. In the UK, in addition to the internal fuse, there is also a fuse in the plug, to protect the flex.
I learn something new with each video of yours Clive. Not sure I will remember it all, but that's okay. Here in the USA (at least in all the houses I have lived in), the GFI is only found within 3 feet of a wet location (IE near kitchen sinks, in bathrooms etc.). Is this also true in the UK, or are the GFI's or RCD's only on the mains breakers?
Oh Clive i've got a good question for you. Here is the scenario: Someone builds a campervan with wall sockets so they fit an RCD after their bus bar and inverter. To do this they build a neutral to earth / ground bus bar and then wire the earth pins of the sockets back to the neutral ground bus bar and also to the local ground which is the chassis and or frame of the vehicle. Now they also decide that they want a way to plug in to an external power source for campgrounds or from their house to use the vehicle as a spare room on their driveway. As soon as they plug in, the RCD in the main building trips because it sees some power trying to flow back down the earth wire (since neutral and earth are now joined in the van). So they are forced to disconnect the neutral from the bus bar each time they plug in externally. Not only is this annoying but what if you forget and you trip the RCD during the night or a time that there is nobody there to reset it. Now normally i assume one should install an inverter that can detect an external power source and automatically switch out the bus bar in the van (or i assume it would be built into the inverter). I see many people building their own camper vans with inverters and i'm just wondering how many people know how to run both an RCD in their camper van and also want to have a way to plug in to an external power source without investing thousands in expensive auto switching inverters. Many people don't plan to use more than one or two devices from an inverter and a floating neutral with one or two appliances lowers the risk of shock substantially but when you have multiple wall sockets or extension leads the risk is greatly increased. Just wondering if you have a simple solution, what would you recommend to people building such a vehicle with multiple wall sockets from an inverter and also have an external power in hook up option? I really doubt that most people have a clue and even i can't see a simply solution other than having an inline plug and socket between the RCD and the wall sockets and this is where you would have to unplug so as to plug the wall socket side of the vans wiring to make the connection to the external power source. And even then you would want to test the RCD in the main building because if it didn't want to trip there could be a break in earth somewhere between or it may in some cases not even have an RCD. In this case if the RCD in the main building wasn't tripping i would revert to the Vans RCD and bus bar and possibly even drive in your own earth stake in case you are using power on the exterior of the vehicle. Does all this sound accurate? Perhaps it could make an interesting video.
If the inverter has its neutral referenced to ground then the answer might be to have the wiring normal with separated earth and neutral, and then plug into either the inverter or the external supply.
@@bigclivedotcom Yes i think the best solution is to have an inline plug and socket that you must unplug from your inverter if you wish to plug into external power. I'm sure than not many people are aware of what they are doing when they wire up home built camper vans.
Really good explanations ! I'll test my clamp with the same method. Which 120 k ohms resistors did you use ? 1/4 W (should be enough) or 1 Watt to be on the safe side ? Any tips on how to build your "6 resistor" device ? Thanks !
I was told in training that using radial circuits with heavy loads would cause to much voltage drop to the last connected device/socket, connecting both ends means little or now voltage drop on any given point
+78Ratje I'm not familiar enough with branch circuits outside of North America, but single-feed 15 Amp branch circuit losses at 120 Volts 14/2 Copper . . . 0.255 Ohms / 100 FT = 3.8 Volts dropped 12/2 Aluminum . . . 0.261 Ohms / 100 FT = 3.9 Volts dropped But either way, that's about 55 watts lost to heat when running an 1800 watt load on a 100 FT circuit. Therefore 3% waste. *Maybe* ring main helps reduce power wasted as heat in branch circuits. While 3% is only of minor significance for one home, this is a significant amount of power when an entire city is considered.
love your vids Clive. when i wired my parents house as a third year apprentice i did both power circuits as ring mains (thought i was very clever lol) each circuit is on a 20a mcb rcd. didnt know it was actually a thing in england.
That example with the plugging in the kettle actually happened to me. We did think it was the kettle, but then we got an electrician in to make sure and of course it wasn't the kettle.
19:09 I agree with that as it actually happened to me once. Basically we had a job of replacing lights in a welding factory and I was in a cherry picker working on disconnecting old lamp from a junction box while the power was on as the factory was working and they needed the lights. Anyway, at one point I turned around to say something to a co-worker in another cherry picker and when I grabbed the steel I-beam construction with my left hand I got a shock of a lifetime to say the least because I didn't notice that my right forearm was touching the disconnected neutral wire coming from the old lamp while the live wire was still connected and ''live''. Vision goes black, can't let go of the I-beam and thinking to myself ''now I'm fucked'' isn't really something I wanna experience ever again. God I hate working on old factory wirings where they don't have an RCD or even proper grounding as neutral and ground are the same wire.
Is not having an RCD even legal? For industrial settings they specifically make RCDs with higher fault currents so they can tolerate a bit of stray leakage from the various machinery but still trip if someone's about to bite the dust. I'd say installing an RCD should be the first thing to do if they don't already have one.
@@demoniack81 It was an old factory 40+ years and all the wiring was still original. Back then they didn't even use proper ground. All cables are 4 wire (3 phases and 1 common neutral/ground). Nowadays everything has to be by the code and properly grounded. In that situation we were only replacing the lights (cheaper option) but in others where we did a complete overhaul (lights, wiring, fuse cabinet) we included RCDs and proper wiring and more if they opted in for DALI smart system.
This is a great tester to use. The only thing is it is a badged up CEM instrument, the DT-9810. This can be found badged under many names on the internet the most popular being the Metrel Handyman version TEK775 . I bought mine from Testermans after returning my AMECaL version along with the leads they sold me. The testers are fine, however the quality of their Fluke 3 wire to 240V plug was terrible. It was bodged together with heatshrink and hot glue where the plasic gland that splits the lead should be! They had not interest when I brought this up with them and they actually shouted at me! Good CEM products but terrible customer service.
Fantastic video. One question. If I put this around the earth cable coming out of the consumer unit and I can see say 28mA, what is that telling me? Is that the aggregate earth leakage of all of the circuits in that consumer unit? Thx
The concept of ring mains is absolutely terrifying to me.I'm from Chicago, we may be the murder capitol of the United states but we also have strict electrical codes.We use conduit in all structures, commercial and residential.When painters break wires off of receptacles they contact a grounded housing and trip the breaker. Don't get me wrong, there are plenty of hack "electricians" here. I take pride in my ability to bend and install conduit, I think it should be common practice everywhere.
+Aaron nutter Even 6Vvac DC coax now is NEC required to be in conduit no.... Wrings out a bid and the customer ends with a just fine and safe but illegal low bid. GTFO of Illinois. Unless you can pay to play for variances from the inspectors. "ring mains" do not even mention the idea state side.
I notice Clive mentioned 32A for a ring main, but our older places are 15A wire fuse ring mained per floor of a normal house, (unless you invested in replacing the fuse wire with RCD type fuses at 16A which was a popular thing to do, much bigger than old fuses so you often left the front cover off). So for example the ground floor (lounge, kitchen, hallway etc) wall sockets would be one ring rated at 15A fuse wire, 16A RCD, and then 1st floor (Master bedroom, kids room, landing etc) wall sockets would be a separate ring main rated at 15A fuse wire, 16A RCD, again, each using 2.5mm cabling, old or new colouring. The lighting circuits would be separate ring mains also, one for downstairs rated at 5A fuse wire, 6A RCD, one for upstairs lighting rated at 5A fuse wire, 6A RCD, I think this was 1.0mm cabling, so four individual fuses at the distribution board just for the basic essentials, then separate fuses for a kitchen cooker, another fuse for a electric shower, another fuse for a 24hr immersion heater, another fuse for a night storage heater on a separate feed, another fuse for a mains doorbell with built in transformer. In new houses they seem to combine the up and down stairs sockets to a 32A RCD fuse yet using the same 15A 2.5mm cabling, a awful idea I think, and combine the up and down stairs lights onto a 15A RCD fuse using 1.0mm or 1.5mm cabling. I would far sooner pay the extra and have a larger distribution board with more fuses! Which is safer? combining the two or having more fuses and more control?
When I began watching, I thought this might be pure product placement as you'd been sent the product. I was wrong. A really informative and easy to understand explanation. Thank you!
As a electrician I'll always recommend watching your videos. I often get questions about how stuff works from friends and customers and gladly show them one of your videos and here is why:
1. I trust your competence and know that you'll have a good explanation and
2. the customer will shut up, let me do my work and not ask every 2 seconds.
You are and always have been such a big inspiration in my life and i am glad / thankful i was lucky enough to stumble across your channel. Thank you!
This video from 6 years ago has made me subscribe today 👍🏾
Thats one thing ive allways liked about you clive, you boil things down to the basic info for learning :-), ive never dug into rcd's but it all makes perfect sense now :-D
My distribution box has breakers, then two earth leakage boxes with twisty reset knobs and test buttons, sockets = 1, lights = 1.
They trigger at 30mA
😅
At the school I used to work at we were given a bucket load of old Fluke clamp meters. Our Cambridge educated head of physics a Phd no less, tested them by putting them round the kettle lead and declared them all broken... So we got given them for the technology department to play with. They all worked fine.
Donald Sayers Now tell us that kettle was turned off and then we know faked PhD.
P.S. Selling any of those flukes?
neg he clamped it around both line and neutral. Need to clamp around either the hot/line wire or the return/neutral wire to measure the current. If he went around simply the whip/cord of the kettle then he was clamping around both live and natural and you will not get a reading.
What an idiot and he's teaching? Another waste of the taxpayers money, and possibly dangerous.
@@davidprice2861 PhD enough said.
I was just thinking about some of the silly things that happened in the physics Dept when I was at school.... then the penny just dropped! Hi Mr S :)
I've learned so much from the videos on your channel. I have been a diy electrician for a good 13 years now in the US and all of your information is invaluable! Keep making these videos for us Clive!
Nice to hear Canada isn't the only country with standards boards that invent overly complicated solutions/tests for relatively simple problems.
Enjoy your videos Clive, always a good show.
Cheers!
I'm happy to see the big fella mentioned the accumulative leakage scenario. I started realising this when we first starting install the dreaded safety switch as they were know then. Now I just use the single module individual RCD on each circuit to mitigate that very issue as we don't use ring circuits in Australia Thanks for the content 👍
after decades of being an audio tech( soundman) it's great to get the basics explained , so thanks!
Thank you Clive! It's so simple, I finally understand how the breakers and the clamp metter works. That always been very mysterious to me
We are all prone to tripping as we get older! Maybe my nickname should be GFCI.
im a uk electrical engineer. i need to show this to my clients to get them to understand. very well explained.
one of the best videos for non electricians..than you for sharing your knowledge
I've been using my amprobe for this application for years, well before it was fashionable. Don't put your earths in the same sleeving though when I come to test that short piece of cable I will need to separate them for ring circuit continuity!
Well presented video Clive. Well done!
If you can't clamp around the ring you could do it round the meter tails and turn breakers on one at a time.
+mikeselectricstuff That could trick you tho, because there could be just a few milliamps on many breaker circuits. Might aswell just whip out the megger if you're going to trip breakers.
+Vegard S. Right, but if you have a suspect circuit, and you kill all the others, that would give you the result. He meant if the ring is inaccessible..
That was utterly brilliant, thank you. Explained everything I had failed to understand from all the other videos I have watched, a bit like when I was at college and a plumber finally managed to get me to understand applied mathematics, when a lot of other people MSC's , PHD's had failed. Some people can teach so you can understand and some cannot. You can, thank you.
I am suffering a nuisance RCD trip out, that is getting worse. I suspect an old RCD and an old fridge, but it could be something else. I like to do my own trouble shooting before I call in the experts and your video has shown me what I need and what I need to do before I call in an electrician to fix the problem. My Dad, taught me just about everything you shouldn't do with electrical equipment; he was a sales manager for Black & Decker so we had lots of tools lying around without plugs both 24v & 110v. Whilst I always made sure that everything I used at least had the earth wire wrapped round the earth pin of the plug I was using, something I know he failed to do on at least two occasions, but lived to tell the tale, I made sure those lessons were never passed on to my sons LOL.
It's just what painters do made me laugh. I spent over 40 years in the construction industry a lot of it in refurbishment.
19:09 - Yes, in that situation there would be a major difference between you and a lightbulb: the lightbulb could be _unscrewed_.
+RFC3514 operative being could...
+Adam Neth - Actually the operative word is _screwed._
I enjoyed the ring main description. I kind of knew it, but always nice to have a refresher as I don't do that work nowadays.
Very useful tool, especially for those intermittent RCD trips, those are such a pain to find out where the fault is without good equipment.
Wonderful Clive. I had no idea there were so many definitions of the word ‘interesting’.
Just about the best explanation of RCd and fault current I have seen Go Big Clive :)
Love this video. Also the magnet passing through the clamp meter showing current was great. Thank you.
First thing when i saw this clamp meter. Need to buy asap.
This is the best explanation of how a rcd works and how to test appliances and circuits. Ring main sounds like a fire hazard. I'm from Australia and we use 2.5mm2 for power with a 16amp breaker. love your videos. keep up the good work
I like the Oz radial power circuits but they just can't seem to let go of their rings here.
About the most useful gadget I bought is the Habotest Socket Tester,very easy to use,and which indicates several faults. I pressed the RCD button to see what would happen,and the whole circuit cut out immediately. I habitually check every socket outlet to ensure its functionality. I have a clamp meter which I have not used yet,usually finding the multimeter adequate for my needs. Very glad to see this video,because earthing has always been a "thing" with me.
Hi Clive, I think the max button is essential for RCD testing. Without it, and assuming there is a fault, as soon as you turn on or plug in the faulty device it would trip the RCD and you wouldn't know the scope of the current (32mA or 432mA) - unless the meter has a max feature.
This was a great explanation of the RCD/GFI (or GFCI) system. Would love to see a video on the newer Arc Fault breakers. They're code in the US now for bedrooms and designed to detect faults between live and neutral.
+sparkplug1018
I've asked the same thing. I read about 'parallel arc fault' and 'series arc fault' detection on AFCI's. I *definitely* wonder if the 230v is able to 'flash over' more effectively, essentially allowing more fault-current flow (allowing normal MCB to be good-enough for parallel-arc-faults), where 110v might tend to sustaion a more 'resistive' arc or something weird like that........
At the moment AFDDs as they are called in the UK aren't mandatory
and I was recently looking up the prices of consumer units, and I made an interesting discovery
This is how much it would cost to purchase each type of consumer unit in the UK, not including installation costs
Dual RCD, 6 Circuits: £59.99 / €69.27 / $83.72
RCBO, 6 Circuits: £109.99 / €127.02 / $153.52
AFDD, 6 Circuits
I am unable to find a pre-populated Consumer unit for this configuration, but the following is based on an unpopulated consumer unit plus 6 AFDDs: £857.69 / €990.59 / $1197.10
RCBO is an RCD combined with an MCB
AFDD is Arc fault detection combined with an RCBO
Hi Clive. I tend to design my circuits around radials now rather than ring circuits. If you need a load up to 32A use 4mm2 obviously taking into account installation methods etc. Another great vid. I have one of the clamp meters, had it for years and occasionally it comes in useful for fault finding. Most times a ramp test off load for the RCD will suffice. I like the idea of the test rig. Will make one this weekend.👍🏻
as an electrician I have found surge suppression devices such as a four gang short extention lead are prone to coursing nuisance tripping. often if the device is on the way out I have found that the variation in supply voltage can make the difference between them making the RCD tripping and putting it on the edge. I have also found high inductive loads such as the vacuum cleaner mostly double insulated can be enough to put a spike into the supply to make a trip go were another fault exists nothing to do with the vacuum cleaner. as for ring mains I absolutely hate them as the testing and fault finding is a nightmare.
+christastic100
Yes! Exactly.... Seen similar with spikes to earth from iffy electric drill, creating similar effects, tripping a "different" RCD to that its' attached to, which has a lot of supression-to-earth stuff plugged into it, probably because of loose earth currents/spikes, going (imbalanced) into L/N of the circuits with the supressors attached... Nice solid earthing, combined with Individual-RCBO consumer units much preferred to minimize these nuisances!!!
Hi, with regards to the non-faulty double insulated vacuum cleaner tripping the RCD when combined an other fault that exists. That other fault could be a Neutral-Earth insulation resistance problem on a final circuit... Imagine that a socket outlet was refixed in a hurry, and the insulation on the neutral conductor became slightly nicked on the earthed metal back box. Under no load conditions, the neutral has basically no current flowing in it. However, when you use said double insulated appliance, the current flowing through the neutral (within in the final circuit), is now shared with the earth conductor (CPC). Thereby, producing an imbalance in the current flowing within the live and neutral conductors inside the RCD, which if great enough (dependent upon the compression fault, i.e. the nick in the damaged neutral cable, which will also deteriorate over time), could cause the RCD to trip. PS. I’ve seen this first hand a few times as a maintenance electrician, so I thought that I’d mention it here.
Why would two RCDs in series trip together, after around 24 hours powered? But when there was only one RCD it did not trip! I didn't find a large current imbalance nor any ground currents. Any tips?
Do you think it could be a marginal MOV, and a voltage spike?
Could a large UPS cause this?
Fantastic Video & Explanation Clive. Keep up the great work. Nick.
I just love your channel - just discovered it and I'm learning! Thanks Clive!
I work for one of the electricity suppliers/DNO's and we upgrade the incoming mains, cableheads/cutouts and metering in houses and flats, mostly for council and local housing authoritities. There has been a trend towards some of these organisations rewiring their houses, and because they are complying with 17th edition regs, all circuits are rcd protected, either dual boards with two rcd main switches with individual circuit mcb's, or with individual rcbo's for every circuit.
This is all exactly as expected, the problem occurs when these houses have electric heating, usually off-peak storage. Some councils now think they can get away without fitting any equipotential bonding, as they say everything is rcd protected, so no shock risk, therefore bonding is not required.
This might be true, if they were replacing the heating consumer units, but in most cases, they are not. Some heating boards are being left, some still only protecting circuits with old rewirable fuses, so the cables are protected from overcurrent and short circuit, but without bonding and EEBADS, there is no shock protection. People like myself, and the companies we work for, have raised this with councils, but they are not all that interested.
+ben kerr virtually impossible to protect against electric shock in all possible cases though. You won't trip an RCD/RCBO when dropping a two-wire appliance in a bucket of water, for example. I guess they don't care about bonding everything when there is no Freezer-only socket, though (considering that some people would still plug in a vacuum cleaner in that socket given a chance).
+ben kerr I've caught the same attitude from electricians "doesn't need bonding, it's all on an RCD". That attitude winds me up no end, I think the 17th edition's requirement for RCDs on everything is a mistake.
Interesting comment. Most cable jointers / linesmen don't know anything about domestic electrics! Yes you are correct but the Electrical industry or the attitude to inspection reports, compliance etc by housing associations and agents etc is a joke just want a piece of paper. I used to get upset about all the non compliances and how blasé people are about it...... I have given up..... They just think you are a jobs worth
Great video! Thanks! It took me a couple of hours to find a N-E fault on one of my ring mains. Which was then down-rated to 20A radial as that fault was unusable (and not wanting everything re-chased out). I'm a DIYer but did it in discussion with my electrician.
Good to know I'm not alone in my ideas about ring mains.
An excellent and very useful video. Thanks for posting this.
Timely advise! Thank you Big Clive. I have some troubleshooting to do around the house and your explanation will help me track down the faults immensely.
Unfortunately, that nice little meter has a $50 shipping fee to the U.S. I can find other clamp meters at the local big box hardware stores, but now I know a feature to look for, and have an inkling of how to use it. Thanks again!
Thanks for the insight on a test cable too! Looks like I'm going to have a few tasks ahead during the holidays. Such fun! (no pun intended)
+PaulyG10657 The main thing is to look for a clamp meter with a small jaw and low current range that can resolve down to at least 1mA.
So far I've been having trouble finding anything with a range less than 2 amps, plus it seems the lower end ones are only AC rated. Will an AC current clamp meter measure DC current?
~I worked as an electronics tech repairing military grade electronics for twenty years (software engineer now), yet I feel like a complete novice asking a question like that.~
Also, if I might change the topic slightly, is 120VAC @ 2A more or less dangerous than 120VDC @ 2A? (Another 'novice' question...so embarrassing!)
The reason I ask is because it seems that some LED drivers come in DC voltages well above 120 VDC, though current limited to specific currents, such as 1400 mA. That allows you to series up to 4 high power (50W) LEDs, which simplifies certain LED configurations schematically, but it seems to me that you trade off safety for simplicity.
+PaulyG10657 Sadly an AC clamp meter will not measure DC current. The AC ones usually use a coil to detect the magnetic field, while the DC ones use a solid state hall effect sensor.
AC is generally considered more hazardous than DC because it causes continuous stimulation of the muscles. But even DC supplies can give a nasty buzz if there is residual mains derived ripple on the output.
Thank you Big Clive. In either case, AC or DC, whenever I work with 'mains' electricity I always do so with an over abundance of caution. If I'm working on low voltage low power battery circuits I'm a bit less paranoid, of course.
DC is worse IMHO as it leaves the muscles no chance to relax leaving a vice like grip on a conductor, it does not take AC to continually stimulate muscles.
brilliant explainer :) I'm a lightbulb now.
This remindes me of a very interesting story our teaxher told us.
Basically he was at a friends house to help with some electricals problems that caused the rcd to switch off when he used his microwave, but only when the lights in the basement where on at the same time.
I have to say that I live in germany and some of the old houses here that were wired in the 80s still have 1A RCDs.
it turned out that the wiring for the lights was faulty because the lamps where connected to ground instead of neutral. Do when the lights where on there was a current to ground at a bit above 900mA wich worked fine. But once the microwave was turned on, the additional small leakage current of the microwave was enough to trigger the RCD.
Really like to see you do AFCI (Arc Fault Circuit Interrupter). Code requires them in residential areas.
+jpalm32 I'm not sure if Arc Fault Circuit Interrupters are required in the UK like they are in the US for bedroom circuits and such. Just so our UK readers know, Arc Fault Circuit Interrupters are designed to detect non-working arcs in faulty wire connections, and broken solid core NM cable (Romex, twin and earth). The AFCI's use sophisticated signal processing techniques to discriminate between a working arc (say from vacuum cleaner motor brushes) and arcs caused by poor connections and faulty wiring.
at the time I am writing this comment, arc fault detection is currently only "recommended", not "mandatory", in the UK
and it was only a year or two ago when the UK regulations even started to mention them, and so as a result until they started to be mentioned they were pretty much non-existent in the UK, and although they are now available here, to fit an entire consumer unit with them could easily cost over £1000 (and a basic dual RCD consumer unit may cost as little as £350 to get it installed, and most people in the UK tend to go with the cheapest option, so unless the regulations change from "recommended" to "mandatory", then I cannot see them being fitted in mass, and even if the regulations did change, unless the prices came down, chances are, as most people wouldn't be able to afford them, then they wouldn't get fitted as often, and also, the regulations are not actually law in the UK)
Clive, I had never heard of a "ring main" circuit before and had definitely never encountered them here in the U.S. Seems to me they'd be potentially rather dangerous. As you said, the wire isn't rated for the total allowable current on the circuit. This isn't a problem as long as you have both paths intact to divide the current load across. But if one leg gets broken, you have, as you'd put it, a bit of a dodgy situation. The breaker allows current to flow up to the 32A limit but with only one leg of the loop supplying potentially all the outlets, you could easily exceed the safe capacity of the wire. Seems like a recipe for fires to me.
TBH, I dont get many RCD's that fail due to oversensitivy, but you'd be suprised how many I get that dont trip at all, pressing the 'Test' button is a requirement at testing, most homeowners have never pressed it, a simple thing to check a device that
could well save your life.
For the record, Im not a fan of Ring finals neither (Not ring mains :P)
Love your channel, a recent subscriber but believe me, im working through em.
Cheers L.
Fascinating look at your circular circuits. We don't have them in the US but in the mid 1960's, it was popular for the Bell Telephone installers to prewire telephone cable in a house in that manner. The idea was if a wire broke somewhere through the house the phone circuit could still work its way around the other way. Much of that cable was like 24 gauge and could break easily.
+CowboyFrankHarrell We have radial circuits too. In fact a few years back there was talk of them making a comeback. But in order to have the same kind of load as a 32A ring they have to be run in 4mm² cable, which is a bit of a fight to work with in a tight space like a 32mm deep socket back box.
The 2.5mm² cable ring mains are run in is a lot easier to use even though you have to deal with two cables at each outlet. Also if you want to add a single outlet to a ring you don’t necessarily have to break the into it - you connect it to the ring as an unfused ‘spur’ using a single 2.5mm² cable.
Hi Clive, I've had real issues with this particular meter and an even worse response from the company. I've tried allsorts of different scenarios and positions etc but Im just not getting the results I expect. In fact some of the results in the 200mA range far exceed the mA trip threshold of the RCD - and thats when testing it on a type A rcd. Ive also tested on type AC and the readings are all over the place. I contacted AMEcal who exchanged the meter after saying it was faulty - however the one they’ve sent ‘calibrated’ is exactly the same results. It took several months to get a reply from the director who then said testing the line and neutral together was not how you do it. After showing him the instructions in the book that comes with it he told me to xxxx off as I didn’t know what I was doing. Then I called straight back and got hold of the ‘test engineer’ who clarified the ones he tested also gives very erratic and unstable readings. All I wanted to do was put the meter around the line and neutral to measure the inbalance / leakage to earth. It even measured leakage with the cpc/ earth removed.
"In the flesh so to speak. ",
I loved that line.
Thanks Clive, I learnt something useful today!
That was a really useful video. Thanks, Clive.
Superb explanation, thanks for creating the video.
only 32 amps? thats like 7680 watts?
not sure in the states but in Canada we get 120V at 100 amps, we do not use GFIs/RCDs at all, it's all breakers. the only place you see GFIs/RCDs is in places with sinks where an electrical GFI outlet plug controls the lights and other plugs.
There is a curseword in German for painters, who are messing with your electrical installation... I learned it during cleaning german earth connectors in walloutlets... "Pinselquäler" which literally translates to person who tortures brushes.
Maybe this anecdote brings as much smile to your face as your amazing "it certainly wouldn't feel like you are a lightbulb" brought to mine.
Rogue trippin' sounds like something interesting to explore. Could it include mushrooms? ;)
Edit: Really nice explanation of the inner workings of a GFI/RCD, best I've watched. Thanks Clive! :)
Rings are genius, they used to only fit 4 way wylex fuse boards (were talking 50 years ago). 1 way for the cooker, 1 for the lights, 1 for the immersion and 1 for the power - the ring main. This would be on a 30A rewireable fuse, so they would run a whole houses worth of 13a outlets on 1 circuit. Back in the day the standard was 1 outlet per room so this method worked well. Now everyone wants 4 or more per room so we are mainly fitting multiple radials per house/flat, and a ring in the kitchen and utility room
Good gadget! There are also DC versions too... as you say, very useful!
Thanks Clive that was a fantastic video!
Explained a lot to me. Informative. thanks Clive
Thank you very much for your clear and informative video.
Great Job !
Interesting! I always figured that the Test button just made sure the breaker could move properly; that's a pretty clever bit of electronics.
Great explanation. always wondered how they work.
I'm not an electrician so obviously I'd never work on the electrical system in the house, but when I am working on the electrical system in my house I always turn off all the breakers. Because I know I haven't got all of the proper insulated tools and all of the safety training, and sometimes there's a circuit where it's not supposed to be, so it's just safer that way.
I learn so much from your video content, from a wanna be Electrician....
When you're ready, try and get an apprenticeship. Better training and money while you do it.
When I saw that meter mentioned in the description I had a look around for it, but at this point in time (and for the forseeable future) I don't see me doing enough electrical work to justify the expense -- it IS a bit spendy. I have on hand here a short extension cord with one of those devices inline. The test button does nothing, so I figured that it wasn't working. Thanks to your explanation of how these things work, I might have to "take it to bits" and see what I can find out about why. :-)
I run a small electrical repair business and find the top trippers are
1. Kettle
2. Toaster
3. Oven
4. Hob
The other issue is small leakage so 2 or 3 appliances on at the same time can cause a trip and harder to find.
Last on was a oven and iron used at the same time
Great explanation! Thank you for that!
"it certainly won't feel like you are a lightbulb" :)
How many Buddhists does it take to change a light bulb? None. Change must come from within!
i wonder if they reurgitate coins at store...
I made an AC Line Splitter that is connected inline with, but after, an RCD. With a male and female plug and socket on either end. To be used after the power point and before the load. I.E. Socket-Plug-Lead-RCD-Lead-Active, Neutral, Earth Split-Lead-Plug-Load. It saves having to break the line of the load. And is meant to be used with a clamp meter when the load is too far from a power point and you can't see the power meter screen at the outlet. And you can measure the inrush on the load. And I double insulated everything with heat shrink and glueline breakouts to split the line.
What a super handy little tool. I think I must have one.
Superb video, all you need to know, nothing left to chance and no silly nonsense
Bloody brilliant, cheers for the info it is so timely
Nice bit of kit (I want one). I worked as an electrician in France for 10 years and got a LOT of critical comments (from the French) on the UK's use of the ring main. A LOT of Brits were coming over and wiring there house UK style. NOT legal here. I had to rewire a number of houses when this was discovered! Still, it kept me in work. :) Keep up the great videos please.
+Eric Gee That would be easy enough. Disconnect ring in middle and turn into two radials, each on their own breaker. I worked in France for a while too. Some other strange regulations. At the time they stopped me wearing a harness in a cherry picker because it was believed it was safer if it started to tip, to grab something and let it go down on its own without you being dragged to your death behind it.
+bigclivedotcom It's not that easy, because here (France), Black can, and often is Live. You could separate the loops and remark(Blue tape) the black wires, but they banned "Twin & Earth" as the Earth wire must be fully insulated here! On the plus side it's warm here (I'm from Sunderland) and the wine and cheese are cheap! Merry Christmas Clive. After saying all that, perhaps "Twin & Earth" is no longer Black & Red!
+Eric Gee The cheese and wine aren't just cheap in France. They are vastly superior to the stuff here. Sadly our wiring colours have been unified with Europe. Twin and earth is now blue and brown. But in the process they changed our vivid phase colours to bland ones. and swapped a phase and neutral colour, which still continues to cause significant electrical accidents.
+bigclivedotcom Thanks for the update. A swear the people who make these changes have never wired a house etc.
+Eric Gee I don't like the L2 phase being black in Europe, it is identical to negative of DC circuits. I do however prefer the new scheme with brown to L1, (black to L2) and grey to L3 rather than the old UK scheme. I would have preferred having L2 purple or any other colour except yellow, red, green, blue or black (to avoid confusion)
Great explanation, Clive. One of the 2 RCDs on my consumer unit is tripping out very intermittently so I bought this tester and it is indicating leakage on a number of circuits. The highest reading is on the cooker circuit (100mA+). As the RCD is only rated at 30mA does that mean the cooker needs replacing?
+Chris Hale That is a lot of leakage, but I would have expected the RCD to trip all the time at that leakage. Is the RCD definitely 30mA? You can do an overall test if you can get a clamp meter round the live and neutral meter tails if they're accessible, then switch circuits on individually to see the differential.
I've checked the RCD and this is definitely marked 30mA (MK RCD model 7860s). With the meter clamped around live and neutral meter tails there's an 'ambient' reading of 20mA. Switching all other circuits off except for the cooker the reading drops to 6mA. With both ovens plus hotplates switched on the meter reads 200+mA, but the RCD doesn't trip.
Did some further diagnosis today and found that when I switch off the mains isolator for the consumer unit I can still see a 200mA+ meter reading when I clamp it around the earth wire. Looks like this could be an issue with the earthing of the mains gas pipe because when I disconnect the earth bond to the gas pipe the meter shows zero current. Any ideas on what might be causing this current to flow to earth when the bond to the gas pipe is in place?
Bonding to Gas pipes is no longer legal practice.
Sounds like you need the earthing in your house sorted out.
The last time I took apart an RCD I found some interesting mechanism for the test button that would be worth a video: Instead of closing some connection there was an inductor wired into the line and the test button would lower a metal tab onto the core of it, closing some short through the inductor, massively changing its inductance and thus causing a short imbalance in current flow
Great review, I just bought one of these testers on the strength of this very good video
Why did the test wire not trip your house wiring trip switch?
+Cashpot
Say RCD "trip switch" is confusing term... Because extra 3mA not enough to trip the "30mA" RCD (which normally takes about 20-25mA typically).
He might have a isolation transformer which isolates the earth return
He could have an non RCD protected circuit for his bench.
Good explanation. When did the ring main get uprated to 32 amps or has it always been rated at that ?
+BillyNoMates1974 It's always been 30/32A - fuses were marked 30A, MCBS are marked 32A. Same for lighting circuits - fuses 5A, MCBs 6A.
Thanks! I had thought GFCI used two torroids and tested the ballance; but I see now one would be much easier to calibrate against itself.
Is there a requirement for RCD protection in the UK now, particularly on lightning circuits? I entered a saturated, humid room (hot tap left on) in a building and got a shock off the light switch before I realised the room was damaged and the switch wet. Should that have triggered the RCD? Because it certainly didn't.
Brilliant explanation, thank you for your time making this video,
I had some really weird tripping because of the street cars(tram)They had big stray currents that found the earth pins of home owners.Really weird problem,but when we tested it soon became clear the thing tripped when a streetcar was pulling from a stop.
Hi Clive.
Interesting video, i was not aware that UK installations was different from the ones in Denamrk, with breakers rated at 32 Amps and loop installation, and i am an elctrician my self :-D
In Denmark the Ground fault interupter breaks at 3mA (By law, since 1975), and the lighting groups is rated at 10 Amps, with 1,5 mm2 cabels, with no loop.
Also in Denmark, usually there is one 3 fase group, with 3 x 16 Amp fuses, 2,5 mm2 cables, in each household.
Love your videos, keep up the good work.
Thank you and happy Christmass, from Denmark.
+Morten Rolsing I think the odd "ring mains" thing are to the UK as "wire nuts" are to the US (well, wire nuts, split phase, open carry, the list goes on). Australia has similar wiring conventions: 10A for lighting, 16A over 2.5mm2 for power points, although you're allowed a 20A breaker if the cable isn't covered by insulation. 3 phase is typically available in residential areas, but not commonly connected (only a single phase mostly), except for specific loads like a big-arsed aircon.
RCD's in Denmark switch at 30mA not 3mA
RCD's in Denmark switch at 30mA not 3mA
RCD's in Denmark switch at 30mA not 3mA
Your videos are perfect for my peanut brain, thanks Clive
Lots of reasons for ring mains, including a) greater current handling, b) reduced cost at distribution board, c) even heating effect (especially in conduit), greater cable flexibility. Not saying that the pros outweigh the cons, but just saying those were the reasons. BTW, current drawn through the circuit doesn't vary according to where it is measured (which I'm sure you knew). Love the videos though
Very well done... was expecting the Amecal would be taken to bits before the end of the video!! ;)
Clive, do you have experience with Arc-fault breakers in the UK? These are now recommended for additional safety in homes with 12/2 aluminum wire branch circuits (typically homes built in North America between 1968 and 1977), when copper became very expensive. While the wires themselves are perfectly safe, aluminum is absolutely intolerant of poor installation workmanship. Wires being nicked, terminals not being tightened to the correct torque, being in contact with incompatible alloys resulting in oxidation, cold creep etc. Which all lead to overheating connections, and ultimately fires. I found it interesting, an arc fault breaker has been designed which can detect this, and disconnect the circuit quickly, just like a RCD/GFI does with ground leakage.
i lived in one of those houses as a child. Fortunately, my father smelled the burning electrical insulation *through the wall* before the house caught on fire. i did some armchair research on it, and i agree with you.
the only thing i'd like to add is that homes have hundreds of electrical connections, most of which are near flammable materials and almost none of them can be inspected easily.
AND, in the early to mid 70's, the construction trade did not fully understand just how fussy aluminum wiring is. these factors combined practically guarantees a bad connection somewhere.
I really enjoyed your video thanks for creating the content.
That all makes sense now, is ring mains perhaps one of the reasons you have fuses in UK plugs!?
+PuchMaxi1988 Yes, because the ring main is rated for 32A but most appliance leads are only rated for 5A or 13A, you need a fuse to protect the appliance lead if a fault in the appliance tries to draw, say 20A through the appliance lead.
+PuchMaxi1988 I think it is the only reason. You can't protect a 0.75mm2 cord with a 32A breaker.
+MrOpenGL Surely not the ONLY reason. As we could just as well still have 32A circuits just using a higher grade wire, the appliance cables would still need protecting.
Alex Atkin
But AFAIK it's the only reason to have fuses in the PLUG, not in the appliance. In any appliance, the fuse is either internal or is on the appliance itself. In the UK, in addition to the internal fuse, there is also a fuse in the plug, to protect the flex.
But what would happen if you accidentally short out the socket? That's a toasty 7680W of unfused power! at 240VAC 32A.
I learn something new with each video of yours Clive. Not sure I will remember it all, but that's okay. Here in the USA (at least in all the houses I have lived in), the GFI is only found within 3 feet of a wet location (IE near kitchen sinks, in bathrooms etc.). Is this also true in the UK, or are the GFI's or RCD's only on the mains breakers?
Great explanation Clive!
15:50 made me bust out laughing! it doesn't matter what part of the world you're in. Electricians hate painters!
Painters and plasterers also.
@@EsotericArctos Plasterers hate painters and electricians......and plumbers.
Plasterers are the real cun%s
It's the plumbers... always the plumbers.
Nice, the lowest setting on my current clamp is 2 A resolution is 1 mA (it can AC and DC) Thumbs up :)
Alex
Oh Clive i've got a good question for you. Here is the scenario:
Someone builds a campervan with wall sockets so they fit an RCD after their bus bar and inverter. To do this they build a neutral to earth / ground bus bar and then wire the earth pins of the sockets back to the neutral ground bus bar and also to the local ground which is the chassis and or frame of the vehicle.
Now they also decide that they want a way to plug in to an external power source for campgrounds or from their house to use the vehicle as a spare room on their driveway.
As soon as they plug in, the RCD in the main building trips because it sees some power trying to flow back down the earth wire (since neutral and earth are now joined in the van). So they are forced to disconnect the neutral from the bus bar each time they plug in externally.
Not only is this annoying but what if you forget and you trip the RCD during the night or a time that there is nobody there to reset it. Now normally i assume one should install an inverter that can detect an external power source and automatically switch out the bus bar in the van (or i assume it would be built into the inverter).
I see many people building their own camper vans with inverters and i'm just wondering how many people know how to run both an RCD in their camper van and also want to have a way to plug in to an external power source without investing thousands in expensive auto switching inverters.
Many people don't plan to use more than one or two devices from an inverter and a floating neutral with one or two appliances lowers the risk of shock substantially but when you have multiple wall sockets or extension leads the risk is greatly increased.
Just wondering if you have a simple solution, what would you recommend to people building such a vehicle with multiple wall sockets from an inverter and also have an external power in hook up option?
I really doubt that most people have a clue and even i can't see a simply solution other than having an inline plug and socket between the RCD and the wall sockets and this is where you would have to unplug so as to plug the wall socket side of the vans wiring to make the connection to the external power source. And even then you would want to test the RCD in the main building because if it didn't want to trip there could be a break in earth somewhere between or it may in some cases not even have an RCD.
In this case if the RCD in the main building wasn't tripping i would revert to the Vans RCD and bus bar and possibly even drive in your own earth stake in case you are using power on the exterior of the vehicle.
Does all this sound accurate? Perhaps it could make an interesting video.
If the inverter has its neutral referenced to ground then the answer might be to have the wiring normal with separated earth and neutral, and then plug into either the inverter or the external supply.
@@bigclivedotcom Yes i think the best solution is to have an inline plug and socket that you must unplug from your inverter if you wish to plug into external power. I'm sure than not many people are aware of what they are doing when they wire up home built camper vans.
Really good explanations ! I'll test my clamp with the same method. Which 120 k ohms resistors did you use ? 1/4 W (should be enough) or 1 Watt to be on the safe side ? Any tips on how to build your "6 resistor" device ? Thanks !
I was told in training that using radial circuits with heavy loads would cause to much voltage drop to the last connected device/socket, connecting both ends means little or now voltage drop on any given point
+78Ratje I'm not familiar enough with branch circuits outside of North America, but single-feed 15 Amp branch circuit losses at 120 Volts
14/2 Copper . . . 0.255 Ohms / 100 FT = 3.8 Volts dropped
12/2 Aluminum . . . 0.261 Ohms / 100 FT = 3.9 Volts dropped
But either way, that's about 55 watts lost to heat when running an 1800 watt load on a 100 FT circuit. Therefore 3% waste. *Maybe* ring main helps reduce power wasted as heat in branch circuits. While 3% is only of minor significance for one home, this is a significant amount of power when an entire city is considered.
Thanks for the video! I definitely want one of those. Can you get them at a discounted price?
love your vids Clive. when i wired my parents house as a third year apprentice i did both power circuits as ring mains (thought i was very clever lol) each circuit is on a 20a mcb rcd. didnt know it was actually a thing in england.
England?
Rizwan Ahmed
That example with the plugging in the kettle actually happened to me. We did think it was the kettle, but then we got an electrician in to make sure and of course it wasn't the kettle.
19:09 I agree with that as it actually happened to me once. Basically we had a job of replacing lights in a welding factory and I was in a cherry picker working on disconnecting old lamp from a junction box while the power was on as the factory was working and they needed the lights. Anyway, at one point I turned around to say something to a co-worker in another cherry picker and when I grabbed the steel I-beam construction with my left hand I got a shock of a lifetime to say the least because I didn't notice that my right forearm was touching the disconnected neutral wire coming from the old lamp while the live wire was still connected and ''live''. Vision goes black, can't let go of the I-beam and thinking to myself ''now I'm fucked'' isn't really something I wanna experience ever again. God I hate working on old factory wirings where they don't have an RCD or even proper grounding as neutral and ground are the same wire.
Is not having an RCD even legal? For industrial settings they specifically make RCDs with higher fault currents so they can tolerate a bit of stray leakage from the various machinery but still trip if someone's about to bite the dust.
I'd say installing an RCD should be the first thing to do if they don't already have one.
@@demoniack81 It was an old factory 40+ years and all the wiring was still original. Back then they didn't even use proper ground. All cables are 4 wire (3 phases and 1 common neutral/ground). Nowadays everything has to be by the code and properly grounded. In that situation we were only replacing the lights (cheaper option) but in others where we did a complete overhaul (lights, wiring, fuse cabinet) we included RCDs and proper wiring and more if they opted in for DALI smart system.
My old apartment (built in the 80's, complete with those fugly sprayed on ceilings) didn't have RCD's, just ceramic and wire fuses..
We've got those (the artex is on the walls though), but someone has fitted an RCD to the "sockets" fuse holder. The rest use fuse wire in holders.
This is a great tester to use. The only thing is it is a badged up CEM instrument, the DT-9810. This can be found badged under many names on the internet the most popular being the Metrel Handyman version TEK775 . I bought mine from Testermans after returning my AMECaL version along with the leads they sold me. The testers are fine, however the quality of their Fluke 3 wire to 240V plug was terrible. It was bodged together with heatshrink and hot glue where the plasic gland that splits the lead should be! They had not interest when I brought this up with them and they actually shouted at me! Good CEM products but terrible customer service.
Fantastic video. One question. If I put this around the earth cable coming out of the consumer unit and I can see say 28mA, what is that telling me? Is that the aggregate earth leakage of all of the circuits in that consumer unit? Thx
The concept of ring mains is absolutely terrifying to me.I'm from Chicago, we may be the murder capitol of the United states but we also have strict electrical codes.We use conduit in all structures, commercial and residential.When painters break wires off of receptacles they contact a grounded housing and trip the breaker. Don't get me wrong, there are plenty of hack "electricians" here. I take pride in my ability to bend and install conduit, I think it should be common practice everywhere.
+Aaron nutter Even 6Vvac DC coax now is NEC required to be in conduit no.... Wrings out a bid and the customer ends with a just fine and safe but illegal low bid. GTFO of Illinois. Unless you can pay to play for variances from the inspectors. "ring mains" do not even mention the idea state side.
Does this work on 3 phase circuits....you clamp around L1,L2, L3 and neutral?
I notice Clive mentioned 32A for a ring main, but our older places are 15A wire fuse ring mained per floor of a normal house, (unless you invested in replacing the fuse wire with RCD type fuses at 16A which was a popular thing to do, much bigger than old fuses so you often left the front cover off). So for example the ground floor (lounge, kitchen, hallway etc) wall sockets would be one ring rated at 15A fuse wire, 16A RCD, and then 1st floor (Master bedroom, kids room, landing etc) wall sockets would be a separate ring main rated at 15A fuse wire, 16A RCD, again, each using 2.5mm cabling, old or new colouring. The lighting circuits would be separate ring mains also, one for downstairs rated at 5A fuse wire, 6A RCD, one for upstairs lighting rated at 5A fuse wire, 6A RCD, I think this was 1.0mm cabling, so four individual fuses at the distribution board just for the basic essentials, then separate fuses for a kitchen cooker, another fuse for a electric shower, another fuse for a 24hr immersion heater, another fuse for a night storage heater on a separate feed, another fuse for a mains doorbell with built in transformer.
In new houses they seem to combine the up and down stairs sockets to a 32A RCD fuse yet using the same 15A 2.5mm cabling, a awful idea I think, and combine the up and down stairs lights onto a 15A RCD fuse using 1.0mm or 1.5mm cabling. I would far sooner pay the extra and have a larger distribution board with more fuses! Which is safer? combining the two or having more fuses and more control?