Vintage RCD/GFCI teardown with story (weird sensing system)

[@CollectiveSoftware]

A perfect storm of mundane faults combined to make quite the mystery!

[@WineScrounger]

It’s clever really, no electronics at all, just clockwork and electromagnetism. It must have been great fun designing these.

[@joepollard8755]

Clipsal (and probably others) still make electro mechanical RCDs

[@rossbaus6816]

I don’t remember how I found this channel but I’m never disappointed listening to you explain these sometimes daft products. Keep it up Clive! ⚡️⚡️

[@petehiggins33]

That transformer core will be made from something like Permalloy which is basically 80% Nickel and 20% Iron. It was widely used for mains frequency and low frequency switch mode PSUs and probably still is. It has a very high permeability which makes an accurate current transformer. It's used in the form of a thin tape to reduce eddy current losses.

[@graemezimmer604]

Correct on all points: Tape wound transformer cores are not at all unusual, especially in Toroid form The thin tape forms laminations in order to prevent eddy currents The metal will be Nu-Metal or something similar (eg not steel) And it's a Current transformer, so one turn is sufficient

[@dhaen]

@@graemezimmer604 I think you meant mu-metal.

[@pizzablender]

@@dhaen Mu metal is malleable, permalloy seems to be harder. As mu metal loses its properties when bent it is not so practical. The name is confusing - the "perm" does not relate to permanent magnets it seems.

[@stridermt2k]

A wonderful exploration and this was from your house as well, in operation through the years. So cool!

[@bostedtap8399]

I replaced a mains "ELCB" circa 1980 in my house with TT system, with a RCD, I wanted to add additional earthing for a Hi-Fi system; adding additional earth's would have compromised it's function. Very interesting Clive, thanks for sharing.

[@Sylvan_dB]

As a young child (age about 10) I had a crystal radio grounded to an outlet screw (which we later found to be ungrounded), with an antenna run along the ceiling thru several rooms. I came home from school one day to find said radio a pile of slag and a line burnt into the carpet where the antenna made contact. Fault analysis determined my younger sister was to blame. :) An errant ball had knocked down the antenna, which made contact with a central heat register in the floor, which managed to drive a rather large current thru the crystal radio to the outlet screw "ground". Potential between the outlet screw and the heating register measured over 100 volts, with enough power to dimly light a 60watt incandescent. The furnace in the basement was newer than the 1950s upstairs wiring and was grounded. The outlet device was replaced which eliminated the "live" ground, and led to the discovery that there was no ground of any kind available to that outlet (only two wires, oilcloth outer jacket, no conduit). The original outlet was a triplex of 2-hole sockets and must have had an internal fault, but that my youthful disassembly was unable to discover.

[@PaulSteMarie]

Those boxes are comically thin from a US perspective. Ordinarily our boxes are about 3-3½” deep, which fits nicely inside of a stud wall. Boxes like those exist here, but they're very much a specialty item. The one time I ran into one it was a real PITA to deal with. Someday I'd really like to send you or John Ward a US equivalent to your "consumer unit". The innards are just so totally different in concept that I find it amazing. That core is acting as an amplifier for the magnetic field, so you're going to be getting more flux in the sense wire than you would without it. You're still dependent on the circuit being AC. Detecting a DC fault to ground would be a bit dubious, I think.

[@Monkeh616]

They're effectively the same as a three-phase DB over here, except they're still made like it's the 1960s. Nothing earth shattering.

[@rose-ey6ct]

About 4 years ago I had a call from my wife's friend. Her cold mains tap had hot water coming out of it. No RCD ( House circa 1955) and a short to gtround in the house. Entire house was a Faraday cage at 230v, and not a tingle anywhere. 8 ohms resistance on the "earthed" water pipe. 8kw flowing down the water pipe resulting in an 8kw soil heater. Isolated fault and asked how long the cold tap had been flowing hot water. - 2 weeks. She had an £800 electric bill for that quarter.

[@samuelfellows6923]

😬😯 - ⚠️

[@nutgone100]

Wow!

[@soupflood]

Woah

[@hovedd]

I remember these very well, late 70, early 80's while working for British Rail. While attending an electronics course at college, I had a project to build a ELCB tester to make sure they did trip, not only at the rated current, but also within the approved time limit. Since these worked on balancing the current through the sense coil, the tester allowed a small amount of current to bypass the the coil, hence giving an imbalance. Cant remember the circuit details, but it counted the peaks of voltage passing after hitting the 'test' button - giving a 'Pass' - 'NoPass' sort of test - very primitive, but I passed the course :) - by the way, great watching these vids Clive

[@Chris_Grossman]

It is called a tape wound core. That is how the toroidal cores for saturating (not resonant) Royer Oscillators are made. It is a torroid with a single turn.

[@aaaaaaaaaassssssssdf]

I had just bought those socket splitters for those hacked dollar store bulbs a couple weeks back... too much fun messing with cheap lights! thanks for inspiring, as always

[@rjmun580]

We were using these fault current operated devices in the UK in the early 1960s, sometimes still using mains water supply as the earth (ground) conductor. I pressed the test button on one at the same moment as the plumber was under the sink disconnecting the pipe. He became part of the earth circuit and was quite annoyed about it. We started using earth spikes for a time but they were soon superseded by the present fault voltage system.

[@johndododoe1411]

What does the "fault voltage system" use as zero reference if not some metal connected to mother Earth?

[@bigclivedotcom]

Some seem to measure voltage difference between neutral and earth.

[@johndododoe1411]

@@bigclivedotcom This was directed at RJ Mun calling RCDs outdated in favour of some system by that name, while simultaneously misunderstanding how RCD test buttons work. Still waiting for him to explain what he was on about, though it might be the IT system, or TN-S with an old school Earth current relay.

[@deltab9768]

A few months ago I was working on this parked trailer/cabin that had suffered a ground fault. It was plugged into this 50A plug that was grounded by a little brass strip going to the screws in the pedestal it was mounted in. The breaker feeding this plug had been disabled, the one inside the trailer didn't trip for some reason, and the brass strip worked as quite an efficient fuse, so the ground wire and everything "grounded" in the trailer became live. It took a while to figure out why turning this breaker "On" would cause a reading of 0 volts from live to ground.

[@alexanderkupke920]

ouch, that could give you quite an "interesting" experience, touching anything grounded...

[@deltab9768]

@@alexanderkupke920 Yeah I think the snow was just cold enough, and my boots were just dry enough, that I didn't become the new ground wire when I touched the metal cover of the outdoor panel 😂. The time where I was working near a pool and water had condensed into the breakers was another story...

[@wattsupmike7593]

Still got one these in my house. Had it fitted in 1976 and felt very modern as all the neighbouring houses on our new estate made do with wired fuses and nothing else. Still works using the test button or one of those plug--in test plugs with a RCCD test button.

[@stephensmith1118]

the shallow depth boxes where usually used on the lighting circuit, the 20mm box was for sockets, spur switches, whilst the extra deep was mainly for cooker, shower circuits... if you thought the e.l.c.b. was fun the older voltage operated circuit breaker where a hoot, a fault on one house could knock the power off for several neighbors too...

[@GodmanchesterGoblin]

There was a device a bit like that in my garage when we moved here 20+ years ago. First thing I did was press the Test button. It immediately went bang. I replaced it, of course, with a newer RCCB. I still press the test button, but no more bangs. :)

[@Quick_Fix]

Always when I see the carnage after an exploration like this of Clive I think: "Okay, now put it back together again". 🤣 And sometimes he actually did, when he shows the item, completely intact again, in a live stream where he mentions it as a soon to be released video, the Patreon supporters already have seen. 🙏

[@FrontSideBus]

I always love the dimpled metal plates that they used to use in old electronic gear. I don't know why, but I just find it pleasing... That rolled steel wrapped core is typical for any toroidal transformer that I've seen so far.

[@zstation64]

Still got that exact same “trip” and Wylex fuse board in use today at MIL’s in deepest, darkest N. Ireland. 😂

[@KarlHamilton]

Bout ye!

[@BHDelannoy]

Watching this video got me thinking about the old heating system we have in our house, wylex HiHeat, I tried researching it but couldn’t find anything substantial. It was fully electric heating controlled by timer and thermostats in each room. Wylex stuff really does last forever, it was still working when we moved in 10yrs ago

[@nutgone100]

I’d love to see a video on that!

[@MyProjectBoxChannel]

I find the history of RCDs fascinating. They were invented in South Africa, to protect people in the mines from electrocution. The early sensing circuit used a special vacuum florescent tube. South Africa was the first country to adopt RCDs as standard, in domestic installations. I think the UK was quite late to adopt RCDs ( Mabe fear of nuisance tripping?)

[@johndododoe1411]

When Denmark adapted them for new installs in the 1970s, the breakers were already a newer style DIN rail units, and any retrofit into existing installs might make it the only piece of DIN rail in the consumer unit. So I'm guessing this UK RCD is from an earlier decade. It may be older than Clive himself.

[@nutgone100]

We had older, voltage operated ELCBs in the UK for TT systems. They were terrible for nuisance tripping I believe (& I think they needed a separate earth rod?). Typical British industry probably just got stuck in its ways & didn’t want change.

[@bigclivedotcom]

Just like we're still dragging our heels with the type-A RCDs, while the hobbyists at the IET invent ever more unlikely accident scenarios that must be protected against.

[@MyProjectBoxChannel]

@@bigclivedotcom they are a protection racket mafia! The stupid one day course to sign off real electrician's work. Don't get me started 😂

[@MyProjectBoxChannel]

@@johndododoe1411 DIN rail came much later for circuit breakers and RCDs, in South Africa. It's nice to see it all standard now. The stuff in the USA is very different, but interesting.

[@tazz1669]

Amazing how simple it is that there is enough power induced through that small wire to create the magnetic force which trips the mechanism. Considering the age of the device I wonder how much development went into making it, no electronics just a bit of electro-magnetic force to push that small pin out and the mechanism to release the breaker. Great seeing such an old bit of kit which no one would give a second thought to what went into it when it gets replaced. In a way it's good it failed so you could make this video for us as you would never have replaced it had it not failed.

[@markjewell2821]

Happy Sunday to you from Sioux Falls South Dakota!

[@PurityVendetta]

Oddly enough I have one of these 'protecting' a PIR light on the side of the house. The feed to it is taken from a lighting circuit on the, much more modern, split load, RCD consumer unit. Very interesting. I'd not given it's age much thought. It used to protect the garage when there was just a pendant light and a single 13amp socket.

[@markchristopher9515]

I called the electrician when you described the cascade of fun. Would've been easier for you to say "Colonel Mustard, in the Conservatory with a lead pipe".

[@Graham_Rule]

That three part lever system you showed at the end was fascinating. It looked like something that could have been around from before the days of steam. But surely resetting it would be complicated as each lever would need to be moved back into place in the right order (and not allowed to press against the wheel until it too was in place).

[@johndododoe1411]

Maybe applying force to the main contact will result in an inverted cascade of levers snapping into position?

[@gregorythomas333]

Pretty damn neat...I love seeing the older stuff and how they solved problems back when :)

[@drfill9210]

Great. I spent hours searching for this on yt. Eventually made my own vid with my best guess as to how these things worked- then i find they you- someone i have subscribed to and watch regularly have exactly tear down i wanted to research before doing my vids!

[@SeanBZA]

That coil is made from Permalloy, which is a magnetic foil used to make tape heads. Used as it is linear, but has a well defined saturation point. The magnetic coil will trip with 30mA of current, and has a tiny magnet that is adjusted to set sensitivity. The coil will only trip on one direction of AC current flow, as the magnetising from the coil increases and counteracts the small bias magnet field, till the armature is able to pull off with the spring tension. Other half cycle the field is reinforced and does not release. I have taken older units apart, Fuchs made ones, which also had that circuit, though the ones from the 1970's made by Heinemann included a small electronic circuit in them, which was a full bridge rectifier, using 2 10V zener diodes for half the bridge, a small tantalum bead dipped capacitor as smoothing, then a BRY39 gate controlled thyristor with a Rc network attached to the positive trigger circuit, so it would trigger and put a pulse of current through the coil if the leakage reached 30mA, or for larger imbalances the zeners would clamp the voltage, and the fast rise would trigger the GCS to fire and trip the coil. More modern ones (circa 2012) have an updated circuit, and use some mains power to have a small electronic circuit to compare the current in the sense winding, and use a small signal thyristor to trip the coil via resistors directly off the mains, so no need for a sensitive coil mechanism. This later one also has lost neutral detection, using a second set of diodes that allow neutral to float up to 1V2 above ground before tripping, so detecting loss of neutral inside the premises, though it does not work with TT systems, but only with TN-CS systems. Came with a set of MOV units inside, that would clamp spikes down somewhat, but would also trip out the breaker on prolonged high mains voltage over 300VAC. New breakers no longer have this, MOV or ground wire, so you can test them with an insulation tester in circuit, just turn off the breaker. Older ones you had to disconnect the outputs to do insulation test. The new ones also are feed agnostic, you can feed them from the base or the top and thy will not care, unlike the old ones which would burn out the trip coils.

[@chrisswindell7517]

We still have some of those huge Wylex RCD's at work, still working fine and passing trip time tests!

[@bigclivedotcom]

It's a very simple unit. No time delay other than a possible lag in the core.

[@danwhite3224]

It's always lovely when you take apart a very old piece of switchgear and a concerning amount of white powdery/crystalline substance falls out of it...

[@tomw6458]

Asbestos 😬😬😬

[@Ramog1000]

@@tomw6458 I would guess its more the shavings from him drilling out the pins

[@deltab9768]

Ah, well, I guess I'll clean it up asbestas I can...

[@bigclivedotcom]

I assessed it for possible asbestos components as I took it apart. Usually Chrysotile.

[@nicholasvalentine3907]

My old cottage is about to have some work done to replace the consumer unit but at the moment it is an old brown Wylex fuse box (6 ways) and an old brown Crabtree earth leakage trip, the trip has a connection to earth and should, if still working as specified, trip if 50v is sensed on the earth. I did the last wiring here about 25yrs ago and yet testing last week with a modern insulation tester came up with good results. The earth stake I put in back then is still good, I intend to keep it as a stake as I do restoration of older pro audio equipment and a good stake gives a cleaner, quieter earth than PME etc. Soon I'm hoping to complete a home workshop which is going to have extensive wiring (more than the house) which is why I have to bring the house up to date.

[@seanet1310]

When Big Clive gets caught out, what hope do the rest of us have?

[@ooslum]

Once had a flat car battery, first time in 3 years. I would have charged it on the garage bench but it was packed with crap so stood it on a box with charger in the middle of the floor. Six hours later the electrics went out and finally found a "boiled over" battery. Stood for a while contemplating the purchase of replacement battery and charger along with fuse replacement only to get a drip on the head from the shower in the bathroom above that decided to leak perfectly in line 5 years after the installation. It felt like Final Destination.

[@daviddavidson2357]

I had a flat car battery once too. Luckily I had packed a hand pump in the car and was able to pump it back up.

[@thebrowns5337]

@@daviddavidson2357 hope you topped up your blinker fluid while you were at it?

[@daviddavidson2357]

@@thebrowns5337 Yeah. I also added some spring water to the shocks.

[@bramcoteelectrical1088]

had a car battery on a mk1 gte blow straight in half...amazing but scary no idea how it happened

[@captainchaos3667]

Earh leakage circuit breaker is still what these are called in the Netherlands ("aardlekschakelaar", literally earth leakage switch).

[@andrew1210931]

My CU has the later 30ma/63A load version of this - a rather decisive clunk/toing when they trip!

[@MostlyInteresting]

Your deepest box is standard in the US. The shallow one would only be allowed for low voltage like under 50, and not line power AC at all.

[@deltab9768]

The 5/8 inch "pancake box" is a thing here too. But it's only used under light fixtures that have a little room for connections in the back of the fixture. no way would an American switch fit in one of those!

[@johnmurrell3175]

From the circuit diagram on the label it looks as though the test resistor is disconnected as soon as the breaker trips assuming it is wired as instructed on the label with the incoming feed to the top of the unit. If the breaker does not trip when tested you probably need to change it anyway so if the resistor burns out it does not matter.

[@wreckervilla]

for such a sensitive mechanical system it makes sense now why it's mounted on rigid fiber glass composite sheets

[@chrisa2735-h3z]

I wish products these days could be this simple and reliable!

[@RobertHancock1]

Ultimately it wasn't reliable though, as it started failing intermittently, which is really bad for a device like this. I think using a pure magnetic trip mechanism for this is going to have reliability problems, the mechanicals involved are just too sensitive and prone to sticking.

[@SeanBZA]

@@RobertHancock1 That is why the modern ones use a mains operated trip coil, to get a high trip force. Drawback is that this coil can then burn out if the breaker is incorrectly wired, as it has it's supply power derived from the output terminals.

[@nomusicrc]

I don’t know why but I love your videos when you end them with the word indeed

[@gyrgrls]

Gotta watch out for those weasel lamps. They go "pop!".

[@SteveDurbin]

I fitted one of these when I rewired my house in 1982 - replaced it in about 90 when it failed in a similar manner to Clive's.

[@jondonnelly3]

We still have one. Seems to work fine. It does trip when it has good reason to.

[@yaidontknowwhattoput]

Audiophiles use those foil coils Usually made from copper either bare or tin plated. I used them for high current CDC circuits. You can shoot a construction nail clear across the room if you get the discharge timing just right.

[@galfisk]

That force multiplication mechanism reminds me of the three ring system for cutting away parachutes.

[@EricWillis77]

The TT system you described is very similar to what we have in the Tennessee Valley Authority system. We have a 8 foot ground rod at meter and on transformer pole that feeds the home. There is a ground wire run down every pole I’ve noticed lately. Maybe lightning protection? Interesting as always. Have a great day Big Clive ⚡️🏴󠁧󠁢󠁳󠁣󠁴󠁿⚡️

[@SeanBZA]

Yes lightning protection for each pole, and also your house ground reference, normally on the other side of the pole so the 2 ground rods do not touch each other directly. The primary side has it's own grounding rod and the secondary a separate one, plus the houses connected to the pole pig each have one at the meter, to reduce the rise in ground voltage with a close by lightning strike. There normally is either a spark gap or a surge arrestor stack by each transformer that shunts lightning induced overvoltage to ground, and spark gaps at the poles so that the energy is absorbed before it reaches the house wiring. Direct hit on the wires your electrics in the house are fried, but the wiring itself survives, which is what the power company cares about. You would need to add your own surge arrestors to the house side, and to appliances, to protect them. Generally the electric stove and heaters survive, though the clock in the stove might not, but anything with silicon inside dies, along with all light bulbs that are turned on.

[@EricWillis77]

@@SeanBZA Yep I’ve had lightning run in the old house I used to live in and it actually burned holes in the edison base screw in glass bulbs. Right through the glass! Also blowed a fist size hole through the steel back of stove! Not a good experience! After the noise and smoke and underwear change and blown fuses replaced all was good. Miraculously LOL

[@stereotypicalLame]

That wire between the poles is called the skywire

[@EricWillis77]

@@stereotypicalLame We just call them overhead lines. Two actually where I’m at. Top is 13,800 volts bottom wire is neutral. At least that’s what a lineman told me once.

[@stereotypicalLame]

@@EricWillis77 I'm not talking about the power lines. I'm talking about the very top, thin wire

[@thijsvanleeuwen]

Guess that is why in the Netherlands the boxes (and tubes) that sit in the wall are always made from PVC. Only old houses (where the copper wire may even be wrapped in paper and canvas) you would find steel tubes and boxes, however the switches would then be on top of the wall instead of inserted leaving room for cables still.

[@chapelchicks8851]

I came for the story...wasn't disappointed :)

[@bigclivedotcom]

One aspect of the story I missed out was my concern that since it apparently wasn't earth fault current (it was) it must have been live to neutral current instead, and 2kW is a lot of heat. My brain then obliged by adding the smell of non-existent smoke itself!

[@kwinterburn]

BigClive if you like the simplicity and elegance of this, you need to do a Gas Valve with a thermocouple flame failure

[@bigclivedotcom]

I'll keep an eye out for that. I'm guessing the thermocouple will power a small coil directly that retains a trigger flap.

[@TechGorilla1987]

A video showing off the new electric kit would be cool.

[@tntgrunf]

6 downvotes (at the time of viewing)? Who the hell downvotes Clive's videos? Seriously

[@graemezimmer604]

They are not necessarily down-votes as such. For many, a down-vote is the only way to stop the youtube algorithm recommending things.

[@alistairboyer]

Ralphy!

[@dcallan812]

Bit odd, I missed this last week, oh well.Great video what ever time it shows up.

[@dottybonkers]

this is the first time for me to comment to a creator. I'm N4IOG, a ham geek scrivenor living in Victoria 🇨🇦. I love your videos, Big Clive. I'm not yet a supporter, but it will happen. I particularly enjoyed a video with you and Ralphie taste testing clubhouse remixes (vodka with designer flavours added). Please let Ralphie know he's much loved too! I always tend to avoid letting components age too much. We had two 1969 thermostats for electric strip heat and we were either turning them on or off. The thermo was a clunky, high current hot system, so we let a Spark replace them as I have a strong preference about working on hot circuits. Anyway, as part of maintenance, everything is a consumable over time. I'm glad to see every time you post something new.

[@jimsvideos7201]

Nice little roll of shim stock hiding in there.

[@petersage5157]

There's a good PSA here - if an RCB doesn't trip when you press the button, manually switch it off and on and try again. You'll still want to replace it sooner than later, but you'll know the reason it wasn't tripping was mechanical.

[@mhbh1979]

Standard Wylex RCD. The coil of iron is a tiny CT. Pretty simple but very clever thing. The 125mA ones for farms and stuff don't even have the test resistor. They kind of rely on the resistive voltage drop on the neutral. Only for the test button mind. I have had a few occasions where the button doesn't work but it tests fine. Earth faults🤣 can have you running in circles. Thing is though, on a lighting circuit unless it's a catastrophic meltdown how is a simple bulb fault going to trip the RCD? The bulb and it's holder, unless metal, has no earth anyway.

[@Keeping_IT_Simple]

What else would Isle of Man house have but TT Earthing?

[@Brian_Of_Melbourne]

en.wikipedia.org/wiki/Earthing_system#TT_network

[@28YorkshireRose12]

When it comes to making illuminated antlers, don't use those cheap LED bulbs - They're no good in the rain, dear! I'm made mindful of an old quote "For the want of a nail, a shoe was lost. For the want of a shoe, a horse was lost. For the want of a horse, a cannon was lost. For the want of a cannon, a battle was lost. For the want of a battle, the war was lost. And all for the want of a nail" - In modern parlance, a cascade failure?! I don't suppose you'd have one of the really old ELT (Earth Leakage Trip) circuit breakers lying around - To explore? I've often wondered just exactly how much they differ from an RCD. I know the mode of operation is different, but until now, never really thought it worth a look-at.

[@millomweb]

11:25 Whatever you do Clive, don't cut the red wire ;)

[@johndododoe1411]

Actually chuckled

[@millomweb]

@@johndododoe1411 I'm pleased you're on my wavelength :)

[@pineappleroad]

I remember when i lived in market weighton, at one point after it had rained quite a bit (and the town cenre ended up flooded, athough i didnt see the flooding in person, from what ive been told the flooding only really prevented vehicles from passing) the RCD in our house tripped after waiting a minuite and resetting it, it tripped again, and eventually it got to the point where it woudlnt even reset fast foward a few days, afte the circuit causing the problem has been identified, the MCB for that circuit is left off (it was a L to E fault from what it seems) fast foward a few more days, i try turning the MCB back on to see if the fault went away on its own, nope, RCD instantly trips, and either the MCB tripped immidiatly as i turned it on, or i hadnt moved the lever on it far enough up for it to latch when the RCD tripped and so it turned off again when i released it, so i reset the RCD fast foward a few more days, an electritian comes in, and they find some old wires (red and black) connected into the light in the kitchen (these wires went off to a different light somewhere, the house had been rewired before we got it, so there shouldnt have been any old wires, the electritian disconnected the wires, and after the power was switched back on, the RCD didnt trip

[@drfill9210]

I've now taken dozens of these apart and I've also pulled the core apart s well. The plastic shield is actually quite easy to remove. I was scrapping the thing when i made my vids, so i had barely any idea what was going on, but it seems i got it mostly right.

[@k4be.]

The single wire passing through the current transformer actually makes the trip coil current higher! More windings in modern RCDs work to reduce output current in a current transformer. Here you have 1:1 ratio so a 100mA fault current would (ideally) pass 100mA through that trip coil.

[@deltab9768]

I tore down a US outlet GFI on my channel.. It had a pair of 16 or 18 gauge wires running through the sense coil, not much for something rated 20A. I guess its OK when there's only a few cm of it and the sense coil works as a heatsink? The trip mechanism had a microchip, a thyristor, then this little solenoid that draws over half an amp, of 120v, for half a cycle of 60Hz and directly releases the clip that holds the contacts down under spring pressure. I'm impressed that someone made a mechanical device that would trip on 100mA and a fraction of a volt.

[@eDoc2020]

Manufacturers can get away with putting more current through a wire because it is a tightly controlled setup. There's a question on the DIY Stack Exchange where somebody noticed a 12AWG wire in their 50 amp transfer switch and contacted the manufacturer.

[@deltab9768]

@@eDoc2020 Exactly. Single conductor, connections rated more than 60C, embedded in free air or heat sinking components instead of a wall full of thermal insulation, etc.

[@uploadJ]

AND all that extra solid-state circuitry is RF sensitive - sensitive to 1,000W of RF energy and sometimes as little as 100Watts on 60 meters for me anyway ...

[@v8snail]

Fascinating stuff. I lost faith in the Hager brand after a relatively expensive RCBO failed to proceed after only 3 years. I pressed the test button to be presented with a buzz, burning smell and smoke after less than 1 second instead of the reasurring click you expect.

[@bigclivedotcom]

Unfortunately that's common with Hager breakers. The trip button initiates the trip sequence, but it fails to trip, and the coil which is only rated for very brief operation is left running. That can result in much more than smoke.

[@v8snail]

@@bigclivedotcom Especially if the smoke is emanating from someone hanging off the circuit it was supposed to trip for...

[@dragonrider4253]

Quite a neat sound at around 9:00 when the device 'tripped'.

[@firsteerr]

i feel so old as i used to fit these when i was starting out !!!!

[@bigclivedotcom]

By our standards they're not that old. Electrical fitements have evolved a lot with time - but not always in a good way.

[@alexanderkupke920]

You mentioned the resistor not being disconnected after pushing the test button. I somehow lost track and wonder which side terminals those red and green wire go to. (I agree, the insulation on those seems to be ridiculously thin. I wonder how far an insulation tester could push those.) Are those hooked to the input terminal or the output terminal? If they are on the output side, the resistor would be disconnected as soon as the test button tripped the device. I could not make out any kind of "direction" from markings or the label as well and technically speaking, for this device it would not matter anyways regarding function. But I can imagine, feeding in from the top and connecting all the breakers to the bottom would kind of achieve this.

[@mikenewman4078]

Clive, I was just thinking after reading some of the excellent comments below that if you were on a NEM system, and the RCD / ELCB jammed like this, the fuse may have looked just a little different. In fact a little smoke may have decided to holiday or even take up residence in the wall box.

[@acrodrigues1]

I wonder if the new rcd allows you to electro-fork sausages again?

[@RobertHancock1]

Surprised that they are still using that sort of electromechanical trip mechanism in RCDs. I don't think that has ever been used in GFCIs on this side of the pond. Of course the trip threshold is also lower at 5 mA so it might well be impractical. Certainly not possible today with all the requirements for self testing and line-load reversal detection etc.

[@theoldbigmoose]

The end part is, I think, the crux of the failure. A little skookum on those pivots etc. will stop the trip. Another recommendation to cycle your breakers say once a year, to keep all the innards from taking a set.

[@ryanroberts1104]

I always find it interesting how early you guys were using those. Big ones only started showing up as standard circuit breakers in the US pretty recently. My house isn't that old and it only has GFCI outlets in the bathrooms and that is it! I wonder if one country reports more "accidents" than the other?

[@bigclivedotcom]

We've used main RCDs/GFCIs for a while, and they will often prevent fires by tripping when smouldering compromises the insulation and causes rogue current flow to ground.

[@ryanroberts1104]

@@bigclivedotcom It's such an interesting comparison - I think of these as modern, high tech devices...while you were still using them with hand wound fuses! I don't think we ever used fuse wire here - just the old edison base fuses. I'm going to have to do some research now, I'm really curious if I can find some numbers for fires/electrocution comparison between the two systems.

[@mikenewman4078]

ELCB means earth leakage core balance, which is a clearer description than RCD.

[@simonschertler3034]

F&G RCD relabeled as wylex. It was one the standard RCD here in Austria. Some guys say that it was made in gdr

[@DaddyBear3000]

My in-laws still have one of these on the feed to their outbuilding. I would have replaced it already, but the armoured needs replaced completely.

[@workmandan87]

Good to see you test your RCDs at regular intervals ;)

[@davidv1289]

Big clive, did you check the resistance through the test switch circuit with the breaker in the tripped position? The contact operating lever (large red piece) looks like it could also operate a set of contacts at the base of the test switch to open the circuit when the main contacts open. Thank you for another interesting video. Regards, David.

[@johndododoe1411]

Given it has it's own winding, I wonder if something in the ciecuit structure limits it's power once tripped.

[@vancouverman4313]

That's a nicely made unit, of British manufacture. Simple but effective, probably has lasted 40-50 years and just wore out from use. It could probably be rebuilt.

[@rexsceleratorum1632]

Recently took a 3 phase unit apart, and the principle was essentially the same, obviously with four wires going through the core instead of two. There was some additional passive electronics to condition the induced current though.

[@rexsceleratorum1632]

I found that the test winding had evaporated complete with _skidmarks_ (probably lightning), but the actual protection system seemed intact. Oh well.

[@bigclivedotcom]

On modern units, when they fail to trip the coil is often destroyed.

[@rexsceleratorum1632]

@@bigclivedotcom The protection system was galvanically isolated, and that might explain why the surge didn't kill it. This unit was only six years old. I don't know if newer ones are different here in India. For example the major brands all still only sell lighting with switch mode drivers in India, possibly because no one wants more resistive heating when it's already 32 degrees C, but more likely because the mains voltage can vary a lot. Thank you for the response and always a pleasure to watch your videos Clive

[@russellhltn1396]

I'm missing something. In the US, the neutral and the third wire ground are bonded together at the main fuse panel for the building. If there's a short from hot to ground, it won't have to go all the way back to the substation. Just to the panel. It will trigger a breaker on overcurrent.

[@bigclivedotcom]

That depends on the system. On this overhead system the neutral and earth are not connected. The earth is acquired locally with an earth electrode.

[@Brian_Of_Melbourne]

en.wikipedia.org/wiki/Earthing_system#TT_network

[@russellhltn1396]

@@Brian_Of_Melbourne Interesting. At a glance, I'm not seeing the US system. It would be closest to TT but with the ground rod and neutral connected at the first panel where the power enters the building.

[@MrDbone75]

Good Monday evening to you sir from wellington Somerset

[@chrismaplethorpe6781]

Rewirable fuses are a pain to sort specially the 5 amp wire. Is that thin is easy to break when replacing it. If having to use the fixing screw as the earth screw a ring crimp makes a better connection.

[@chrissnyder2091]

There's a type of toroidal transformer that is used in high frequency switching power supplies and the toroids are constructed with a high permeability tape round in the Taurus shape.

[@johndododoe1411]

Bull shape or torus shape?

[@chrissnyder2091]

Lol not a Taurus shape.... Autocorrect strikes again.....

[@jtveg]

Thanks for sharing another interesting device teardown. 😎👌🏻

[@Mr.T4LLY-0]

Old as the dust it's collected over the decades. Nice teardown. Would be nice to hear from any people out there that were in the manufacturing process of some of these items. Anonymously if it's a teardown of shame XD

[@rossthompson1635]

How long was it sitting in that fault state? 8 Amps or about 2kW, that could be a hefty electricity bill. Good job the fuse finally melted, rewireable fuses will sit with an overload for a surprisingly long time. That type of fault on a 30 Amp circuit could be very expensive if you had been out of town, or didn't have a power monitor.

[@bigclivedotcom]

Thankfully I don't think it was long. But it could so easily have been sitting there at the fuses maximum ability to maintain the current for a very long time. Very annoying that the power monitor had decided to lose communication at that time. (It does so from time to time, possibly due to something locally jamming the signal.)

[@Mark1024MAK]

So Clive, when did you last test that ELCB before you discovered it not working correctly? It’s not unknown for me to trip my RCD when working on the lighting circuits in my home, I do switch off the MCB for the circuit, but it’s the neutral that is still connected that does it! My spilt load consumer unit has RCBOs for the ring circuits, the RCD protects the lighting circuits, the cooker and the immersion heater.

[@bigclivedotcom]

Fairly frequently. Often accidentally. So it was a genuine surprise when it failed to trip.

[@EasyOne]

Very well explained

[@vancouverman4313]

The "Blue Collar Trash Chandelier" looks like a pacifier for Quintuplets.

[@ralfbaechle]

So the trigger mechanism contains what is a kind of a mechanical darlington amplifier. Neat indeed.

[@LadyLexyStarwatcher]

Lolz, my bedroom has one of those ceiling fan lamps with five light sockets. I have five of those LED bulbs with the strip of LEDs held up by wires you know. Center is red, then round the outside are orange, yellow, green, and blue. =P I have a thing for rainbows. Funny, they average out to white when they are all on, but shadows in my room are really crazy and colourful. I have to have the blue facing away from me because it makes my vision all blue and hazy...It seriously causes things to fluoresce.

[@xtevesousa]

I hope you don't really mean literally fluoresce, because that plus your other details would point to a UV bulb, which will cause you eye and skin damage! BigClive has a video about an incident were UV bulbs were used in a public space, check it out to see if that's what you got.

[@eDoc2020]

@@xtevesousa Given that UV-C LEDs are seriously expensive that's probably not what the OP has.

[@Aristo12]

Thanks for reminding me to regularly test them.

[@farmersteve129]

I'm surprised that you went for a split load board - RCBO boards are very reasonable these days & being on a TT setup N-E faults can be a right pain to diagnose - aside from the hassle of having half the house without power!

[@bigclivedotcom]

I'm not thrilled by how much they're jamming inside RCBOs. I've been sent a few that have failed with an internal arc flashover initiated by electronic failure.

[@markfergerson2145]

Thirty ohms between your home and the power station... how many meters would that be, roughly? I know it's quite damp most of the time on your Isle but that's very low soil resistance compared to what I'm used to. You don't see power circuitry like that in the US much these days because we get actual summers and the ground resistance climbs rapidly. I used to live in Phoenix Arizona (in the Sonoran Deseret, hint hint) where there were thousands of miles of copper wire just for the ground return in all of the city's power circuitry. When copper prices started climbing, thieves would go out and cut what they could from LIVE LINES in obscure locations. This had fairly obvious effects so some of the smarter... I mean slightly less stupid... ones began stealing ground return wire which had as you can imagine somewhat stranger, harder to trace effects. Oh, that thing you were marveling at looks like a minimalist current transformer. Damn things always struck me as black magic what with using theoretical "A fields" instead of ordinary mundane B fields.

[@bigclivedotcom]

It's not a huge distance, but was still impressively low.

[@dimitar4y]

wow they don't teach you in school about tiny copper spikes causing faults in summer. Nice timebomb!

[@Nuts-Bolts]

Ye not in Scootlund noo Clive. TT stands for “International Auto-Cycle Tourist Trophy”

[@MD4564]

How come it's TT but not IACTT ? for politically correct acronym ?

[@iamdarkyoshi]

That end bit is what I'd call a mechanical darlington pair

[@poellot]

Did the fault cause the power meter to work incorrectly?

[@bigclivedotcom]

No. It would be registering the fault current as being consumed.