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Totally exploded Hager RCBO (RCD/GFI with overcurrent trip)
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- Опубликовано: 1 май 2018
- I've always pondered whether cramming the RCD/GFI circuitry into a breaker designed to break up to 10,000A of fault current was a compromise. It turns out it does open up the possibility of an internal flashover.
My guess for the fault scenario that caused this is that the switching contacts welded shut allowing current to continue flowing, the electronic module tried to trip the welded mechanism, and then burned out initiating an arc that allowed the live to flash over to the neutral.
John Ward featured a similar breaker failure. His video is here:-
• Failed Hager RCBO Tear...
I'd suggest resetting these breakers with extreme caution if you believe there to have been a major fault condition that may still be present. The presence of the Live and Neutral connections in the same enclosure raises the risk of plasma/explosion hazards.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.co...
This also keeps the channel independent of RUclips's advertising algorithms allowing it to be a bit more dangerous and naughty.
It's interesting that some RCBOs have the extra earth wire for sensitivity for loss of earth and Reverse polarity tripping and others do not. I have used Hager three phase disruption gear and never opened up an RCBO, too expensive with top brands when still working. Really interesting to watch and hear Clive show about the workings and it's components.
“The more you complicate the plumbing, the easier it is to stop up the drain” -Scotty
FlatBroke612 Scotty Kilmer?
That sounds like a scotty-ism.
@@HighestRank rev up your engine
@@HighestRank Montgomery Scott, Chief Engineer, USS Enterprise
Absolutely true that’s why my car has a carb and points and a manual trans if it fucks up you can fix it on the side of the road with basic tools that you have with you look at piston engine GA aircraft you aren’t allowed to have electronic ignition or electronic fuel injection (at least not on a certificated aircraft because I know someone is going to bring up experimental and ultralights)
I chuckled at the "JW here" impersonation, love it.
Clive, when you do eventually drill/cut/burn your hands on camera enough to require a hospital trip, remember to take your camera so you can continue to document the event. :)
Let's hope he never has to visit a proctologist.
Including the taking-to-bits of random hospital apparatuses!
That's assuming that superglue isn't able to do the job of repairing mild wounds.
I missed a trick there, I had a drill press whoops before Christmas and slashed a full thickness gap in my left hand. Would’ve made quite a good ‘tube.
@clive I did consider superglue, briefly, but it would have needed several of those little bottles and I thought ... nah. Not going to help me this time. Gonna have to be sutures. It sucked.
bigclivedotcom superglue your medical ID card to the camera right now.
When a circuit breaker becomes a fusible link.
At the right voltage and current, _anything_ can be a fusible link. Life goal: Never be that thing.
I mean, you can guarantee that you'll succeed in that life goal, if you're willing to measure your time of death as the instant before becoming that thing occurs.
Doug Sundseth no Clive said it looks like the fault was likely to have blown itself clear somewhere downstream, so the breaker didn't break the circuit like it should have if after faulting it became the weakest link.
Acting as a proper fusible link would be the _best_ case failure for a circuit breaker: _permanently opening_ the circuit internally.
In fact as near as I can see there was no fusing of _any_ kind involved in this failure, since the ease with which Clive separated the contacts indicates a cold weld (more similar mechanically to soldering or brazing) rather than the, um, _fusion_ of a proper weld.
The current spike probably spot-welded that thing together.
@@Azlehria that's so scary! honestly surprised breakers don't include a backup fuse to handle large faults that weld it closed
Very interesting that the first sign of a problem was nuisance tripping. I became involved with an installation where the main board was loaded with breakers of the same brand. It started with one nuisance tripping so I replaced it. After the third failure within two weeks the whole lot disappeared into the round filing cabinet. I replaced them all with Clipsal breakers and no problems since. Luckily none of the breakers in this installation moved on to the pyrotechnic stage. I have been using Clipsal breakers for a long time now and I have never had a problem.
I love your work Clive, thank you for the post mortem.
The way you went through the fault finding route reminds me of the tv program called "Air crash investigations". 😀
And in some cases I always wonder if I did come to the correct conclusion. And also wonder if those air crash investigations also came to the correct conclusion.
bigclivedotcom LOL!😁
So I learned two things from this video: 1. The breaker clip thing, and 2. Drilling out rivets. I have always punched them out with a hammer, but drilling them out is so much easier. Thanks Clive!
I've never seen so much magic smoke residue in one small component in my life.
HUGE POWER SURGE, aka lightning strike ;)
My y fronts look like that on the regular.....
That's something that used to happen where i worked, peiople would keep resetting the breaker thinking it would clear the fault.
I think that's what happened there, the continual resetting has caused some of the blackening, the rcd trip coil has been powered for a long time and that has overheated causing the bobbin to melt, seizing the plunger.
I can't remember where the neutral runs to get to the other end, my guess that it is clos enough to the live and flashed over causing the majority of the blackening and 'sputtering' of the copper.
We didn't like Hager, crabtree was preferred, you could get rcd modules to convert a mcb to rcbo, neutral didn't pass through the mcb section.
Yeah. People don't seem to understand what the circuit breaker is there for in the first place. If the breaker keeps tripping. Don't just turn it back on. Find out why.
In fairness, once you've welded the contacts, I find that "blowing up the RCD circuit" is pretty low on your worries list.
I usually lock the whole sub panel box been bitten to many times by people getting home and turning breakers back on when I'm working on the system...
TheMFrelly fuck that.... Hazards of the job eh!!!! I can't imagine anything worse than being hard at work, thinking your safe and getting a bolt....
TheMFrelly who in your household is going to a sub panel to check a circuit? They must want you dead.
Just what we see in the Southern US when we get a direct lightning strike to the mains or load. BOOM! I tried various lightning protection strategies, but the problem finally stopped when I built a large metal shed on the hill above the house.
exactly what I said in other comments, it looks 100% lightning/massive surge related to me ;)
It is interesting to see how the test circuit creates the imbalance to trip the circuit when tested. I had assumed (for no valid reason !) that the test button caused a current to earth that was detected and tripped the RCB. However that is not what happens - the test button causes the test current to bypass one side of the sensing coil thus creating an unbalance. However the test current is still flowing from Live to Neutral not to earth hence testing a downstream RCD does not trip upstream RCDs as they see the test current as balanced. Very clever when you realise.
Awesome teardown. Thanks.
Nowadays in Australia where I live the newer RCDs always have an overload breaker built in and they are no larger than a normal circuit breaker.
We remove RCD main switches because any ground fault cuts *all* the power to the house which is very inconvenient.
So we put RCDs on individual circuits instead. We also delibretally leave some circuits without RCD protection. Oven, Air conditioner and usually one power circuit.
John Thimakis Why leave an RCD off the oven and A/C? If the chassis went live and you touched it wouldn't an RCD be good?
Matthew Lindsay
Some devices like the air-conditioner tend to cause a lot of false tripping, possibly because the boards are exposed to humidity since they are outside. Even the indoor unit creates a lot of condensation that can cause the RCD to play up, ie falsely trip.
A fault to ground still causes the circuit breaker to trip because all metal chassis are grounded to the earth wire and all earth wires are connected at one point in the main board to the neutral wire.
This is known as the MEN system (multiple earth neutral). So if a live (active) wire touches an earthed chassis, you effectively get a short to neutral via the earth wire. So the breaker still trips.
well you need to get a less sensitive RCD for those devices then but none at all isnt just dangerous but in many countries actually illegal.
Chuckiele
We'll in Australia it is not illegal to have a breaker without an RCD feature.
The other point is that although you could probably get a less sensitive RCD, I've never seen one. They are all set to 30mA. Also it would defeat the purpose because more than 30mA through a human body is dangerous.
The scenario is that RCD trips and won't reset, but after a few hours, when the humidity has dried out it can be reset.
This becomes very inconvenient. So the best and most economical solution is to have a normal breaker on that circuit.
As I already mentioned this still trips the breaker if the chassis goes live. What it doesn't protect is if you happen to open the unit and touch a live part.
Well here in Germany its illegal to have any wire leave the distribution board without being ground fault protected. Thats why most households have a single insensitive 3 phase RCD from 30mA up to 100mA. They arent protecting someone from stripping off a cable, plugging it in and touching live and earth, but they protect you from dropping your hair dryer into the bath tub or a device failing internally and leaking to earth.
Me and my dad only use these in domestic settings. There's an amusement arcade our landlord owns about 10 yards round the corner from our house & the distribution board is a split load board for each section. There's 3 phases coming in with a split load board on each, powering about 6 areas of the arcade floor.
There's about 80A load on each split load RCD in total (they're 100A RCDs, 2 per board) and there's 2 Hager boards there (dad has always seen them as reputable and no issues to this day really). There's a Proteus board there as well (newer metal enclosed one because of the 17th edition 2015 update).
If this happens more regularly with hager switch gear, i might consider switching them. All the stuff in our home is MK or Schneider luckily.
S.A. Smith I
Hi Clive :)
In France with our breakers if you can put a lock on a close one it's no problem. the lever on the front isn't directly driving the internals, it's only an indicator.
I already had some circuits breaking and all levers where up so i had to find the one tripped and close it by pulling down and up the lever.
So if it's a sensitive equipment that you don't want people to bring it up if there is a fault you can also lock it up and if it trips the breaker people without the key wont be able to do any action on it.
(it's a clever idea but not sure if all breakers has the same internal behavior)
tested with Hager / Legrand)
Clive's best line, (opens up the breaker) oh that's not happy is it.
bryce11544 'dumb-it-down-Clive'
Hager had big recall a year or so ago. From memory it was MCB's not RCBO's. Interesting video, especially as I have fitted Hager stuff for the last 20 years. On the whole they are reliable though in my experience.
Great analysis.
I had some experiences of my own with welded contacts in an industrial design project, but the contacts were those of heavy-duty relays. I learned a few things. It's a scary failure mode, particularly if there's nothing else downstream in the way of protective circuitry, fuses, etc., and the machinery in question poses a potentially major fire hazard. In our case there were protective circuits but their job was... to switch off the relay. The one with the welded contacts. :-/ Damn good thing the problem emerged in the prototype stage. The relay was SUPPOSED to be so over-rated for the purpose that no such failure was even possible. Got it sorted out in the end and the result was nice and bulletproof. Fixed it three different ways, actually. The design has remained in use now for 25 years in thousands of machines with zero failures of which I am aware.
It's always good to design in multiple protection against failure modes. And as a last resort in extreme cases, add a crowbar circuit to deliberately trip protection.
How did you solve the problem?
A mcb above the relay or a fuse link separator?
@@florind.5711 The primary problem was noise in a temp-sensing circuit that overwhelmed the built-in hysteresis. Probe wires were acting as antennae, picking up AC noise and switching noise as well. I even detected a nearby powerful AM radio transmission on some of the probe wires. We fixed that rather firmly with some hefty ceramic filter caps at the entry points of all the temp probe wires. The relay logic circuitry was modified to add further chatter protection by imposing ~150ms logic-state switching delays. And a thermal fuse for ultimate mechanical shutoff on overheat. The thermal fuses have never in any case been tripped to my knowledge in the decades since.
The welded contacts remind me of a time our old (1999) 10kVA UPS ran until all three battery cabinets were depleted. Once we got the mains back up, we had to run on bypass until the vendor could come out to give it the old crowbar and hammer fix.
I just replaced a Hager 10A RCBO 2 pole single width that failed to trip with the test button after only a couple of years. It would buzz and start smoking within a second of holding the button but not trip. I tore it down and discovered they had incorporated the RCD and overload coils in the one aluminium package. Some clever engineering in the linkage was supposed to trip the lever to half position to indicate an RCD fault and full off to indicated an overload in order to diagnose what had actually tripped it. In reality, the linkage ended up binding and preventing a trip on either RCD or overload. I could not see any thermal trip strip in there.
The resistor for the RCD test was still intact and measured 3250 Ohms so at 250V would draw 77mA and dissipate nearly 20W. No wonder it smoked after less than a second. It seems they tried to get a little too clever for the room they had to play with. It has tainted my faith in Hager products now.
I think the failure of the coil in the same way has caused catastrophic failure inside these breakers.
I think I agree with you, Clive: this doesn't seem to be a "one-time cause" catastrophic failure. Many, repeated trips with an inductive load is a good guess. Poor thing killed itself trying to open the contacts.
SigEpBlue Heroic thing killed itself clearing one last fault. While ugly this is a much better failure mode than the house or game machine burning down from an uncleared fault. The thing had already been abused to failure, and now the owner has no excuse but to call in an expert to replace and troubleshoot.
Actually after the contacts welded together Im quite sure the last fault was cleared by the main breaker :D
I innadvertantly back powered one of these whilst using a single circuit from the previous install whilst commissioning the new set up with much the same effect. I put the power on and heard a buzz for about ten or fifteen seconds (the time it took me to kill the power) and saw that is let the smoke out of the RCBO. Own fault and own money to replace the failed part. £25 lesson, well learned.
That would have been the trip coil activating, but failing to break the power due to being fed from the wrong side. It's a common cause of these things exploding.
C3 also limits inrush current to the thyristor trigger. We had problems with that issue, especially on higher power devices (6 to 8 inch diameter chips) and, in an extreme case, the Silicon can actually splinter off the top surface, in a saucer shape, taking the gate contact with it. The solutions to the problem included multiple trigger contacts on the Silicon surface, plus careful Silicon doping design, and external inrush protection components, such as that cap, C3.
I just want to say thank you for these videos, I may not be into electronics (although I've learned a few interesting things from these vids), but I find these videos along side some smooth jazz or lounge music make for the perfect background noise while studying, with the music combined with your calm voice and the various clicks and whirs of your equipment.
Its very common for old CRT arcade machines to leak a small amount of current to earth in operation, so when you have a large number of them, they like to randomly trip RCDs, even type C, we've done alot of experimenting with it and it definitely is the monitors
Thats a little scary when the contacts weld closed
I would call this type of incident a "Hard Failure"
As in...when the fault trips the unit but the contacts have welded together.
I used to work at Bulldog electric in Detroit, in the lab where we UL tested circuit breakers and starters. Lots of burn marks on the wall, and good fun.
love the smell of burnt breakers early in the morning and terrified late at night !
@6:38 When Clive said, "oh dear" - and you don't hear that often from him - you know somethings fu****up
I like when you share extra knowledge while opening circuits or other.
Heat the beans Martha, it's toast.
Looked like someone discharged a large cap bank, damn that thing is cooked. Never thought they can blow up this bad just from normal use.
If you keep resetting the breaker several times without investigating the fault, that's hardly what i would consider as "normal use".
That's actually why i prefer regular fuses over these breakers: The average user tends to call an electrician when the fuse blows second or maybe third time.... With these breakers (or as they are generally called here: autofuses), people tend to try numerous times to reset it, resulting in major damage to the breaker. Or even worse a fire.
big cap bank discharge.
Or a big cap bank charge? If it was switching on a row of computers with capacitative filtering on the intakes, you’d get a strong surge of current straight away.
Regarding "average users" and fuses - that's how you end up with fuses "augmented" with aluminium foil / thick stranded wire / straight up nail whenever folks run out of fuses. Calling an electrician? Not so much.
@John Rasmussen I have to disagree. A couple of years ago every houshold had normal fuses but most people did not call an electrician. Instead they wrapped aluminum foil and other stuff around the fuses and put them back in. There is a reason why we don't use fuses anymore.
Had to be a Voltage back "SURGE" I found, over years GFI, Outlet devices, with MOV, "Metal Oxide Varisters" really, "Draw" the surge to circuit boards. Electrician for 45 years.
Breaker locks where one of the best investments I ever made.
This is an expensive little device, I had to think few times to have more than one installed in my house but safety is the most important aspect to be considered here.
That was definitely turned into charcoal, must have made a nice bang when it went... :P
I like that method of fault notification: "a loud bang."
Probably not locally unless the breaker was energized and circuit live while it was inserted, and the panel connection made the noise.
The generic device is RCD - Residual Current Device
There are two varieties of RCD:
RCCB - Residual Current Circuit Breaker
RCBO - Residual Current Breaker with Overcurrent protection
However, RCBO's are newer/less common than RCCB's, so it became usual to refer to an RCCB as an RCD when there was only one type of RCD in general circulation.
So now we have RCD and RCBO.
I've trained to be an Electrician, my guess is IF the Breaker Contacts welded shut due to a dead short somewhere in the Branch Circuit its supposed to be protecting, the next thing to trip would be the Mains Breaker protecting the entire Distribution Panel (hopefully before the Branch Circuit wiring caught fire from WAY too much Current flowing through it).
Tripping the Mains Breaker would also have the fun side effect of killing power to the entire building...
I would love to see the insides of an MCCB sometime soon.
Even better, a breaking up of an ACB. They seem to have the same technology as a satalite nowadays.
Daymn, that's so smoked I can smell it from here!
(Not completely joking either, I know that smell well enough that I can 'almost' smell it)
Clive, The name RCBO always made sense to me because I called normal (human safety) RCDs RCCB - Residual current circuit breakers which I believe is the more specific term, you can have other type of RCDs I think.
Mike was playing with his destruct-o-tron again ;)
"Oops" :)
by 6:50, that had to be a direct or nearby lightning strike with huge voltage and surge currents. I'm betting it arced from the wire passing through sense coil to the control circuit and up stream as it tripped. I've seen many GFCI outlets look the same way from direct power line/pole strikes ( above ground electric here) lost random devices all over my own house in the past, it hit the whole street of people randomly killing devices also.
I'm betting the same thing occurred on "John Ward's" video you linked, only it didn't trip catastrophically, only damaged the control circuit and went kaboom, when tested.... which is exactly why they say "test weekly" on all the GFCI's in USA. the one you had looked to be obliterated instantly, Johns looked to be a death trap that could have electrocuted someone!
Yeah, our family ran a pinball machine (and some other arcades) hall back in the -70 and -80’s and i remember we had huge problems with power, nothing a screwdriver fuse couldnt fix!
Pinballs have high inrush to their transformers. The best approach is a lot of circuits. That way only a few machines go off if a breaker trips.
bigclivedotcom yes I remember it was extreamly important what machine was plugged into what extension cord in order to balance it out on the phases. I really liked the electronics in the old pinball machines, one of my jobs was to clean and spray contacts that eroded constantly.
Yeah, until the building burns down because you didn't have a proper fuse and an electrical short occurred! I tried fixing an older pinball, where the owner had bypassed multiple fuses. Several transformer outputs were dead and the motherboard was fried. I didn't bother.
Sophisticated electrian slang "totally exploded" 😂
I would suggest the power lines were subject to a lightning strike and the resultant surge has destroyed the breaker.
damn, these appear to be the same model I use at work.
Reckon this is an isolated issue, or something I should consider getting rid of, and finding a different model/brand replacement for?
In my setup, these are connected to modern monitors, no degaussing coils.
They should be fine if they are being used within their ratings and are wired with the feed at the correct side.
Like Clive said, the issue with this one is that the owner kept resetting the breaker through the fault. That caused arcing and burned the contacts until they welded together. Most likely they turned all the machines off at the end of the night with this breaker and it arced every morning when they turned them on. The real fix would be to put in another breaker and split the load, but then they'd have to run new wires.
Cheapest solution is to turn off enough machines on the circuit to bring the load down on startup either at each machine, or wiring in a time delay startup relay or manual cutoff switch into the line to cut power to like half of the machines until the other machines are started. I'd check if current on the breaker was close to it's rating though to make sure that circuit wasn't over loaded though.
Time delay relay ruclips.net/video/nTx9n8BNhgQ/видео.html
Rapid make-break cycles is worst of all. When contact is broken (switched off) arcing is sometimes at its worst. If it's switched back immediately (or god forbid, it chatters), the hot contacts have a much better chance to weld.
Alternate Solution if you want to keep the luxury of switching all machines off and on from the Distributor (or another easily acessable location): Add a Switch + a Contactor for each Circuit and toggle the Switch instead of the Fuses - no new Cabling needed, and the Wear is moved to the Contactors which are actually intended for this purpose
The casing contained the shrapnel very well possibly preventing it catching fire?
It did do a good job of containing the bang.
Had a similar situation with a mem3 rcbo, like the Hagar you've got it has vent holes on the side. The energy vented into the rcbos next to it via the vent holes and damaged those also. Consequently we no longer use mem3 due to this design flaw. 😀
Imagine if the energy did not vent. The breaker would explode.
Prehistoricman different manufacturers have better ways to dissipate the energy in a different direction. Schneider for instance, I've never had a similar problem with their rcbos.
I couldn't find any info on their vents. That said, I'm skipping through this video here and I don't see a vent at all.
I think I understand your first message now. You're saying that the cases of these MCBs have weaknesses that tend to blow out.
Oh that isn't happy!
I think I have a board full of these protecting my house...
Briarhook Gaming shut up, you cretinous waste of space and oxygen.
Makes me wonder about the *2-pole* 1-module RCBOs available from some manufacturers (although to be fair, those are only rated to break 6kA at most).
If the test resistor contributed to the bang, then using a fusible type should help. Adding a fuse in series with the solenoid (possibly a thermal fuse mounted to the coil) could also improve the situation (although it would have to be chosen carefully to avoid blowing when it shouldn't, which would be nasty in its own right)… I suppose the welded contact is bad enough on its own, though.
Use the Force, Big Clive! :P
Tripping and not catching reminds me of the one breaker in my old apartment...which controlled 2 bedrooms, 1 bathroom, 1 hallway, and half the livingroom.
Addition to the electrical lexicon "Plungery" :)
I suppose all you would need for overcurrent protection alone would be a shunt resistor and a spring loaded relay. The coil of the relay with the shunt resistor across it, 'live in' on one side of the switched output, then looped back to the coil, 'live out' on the other side of the coil. If too much current is drawn, enough current will flow around the shunt that it will trigger the relay.
Contacts welding together sounds like the worst way a breaker could fail.
Now we're all waiting for the next video of you repairing that thing :D
The big unknown. What's the history of the device? Constant resetting on a fault? Lightning strike? Wired up wrong?
And the device, while it did blow up, stayed intact, nor did it catch fire. But then any device being subjected to fault currents tends to leave black marks somewhere. I've seen the results of a whole switch panel blowing up. Just a hollow shell left with copper busbars splattered everywhere. Same with a lightning strike on a house where it was a total rewire due to the cables melting together. Faults happen.
You mentioned that it came from an arcade....well, most arcade games use switch mode power supplies (basically like home computers) and older machines use regular power supplies with transformers. Switch mode power supplies usually draw a very brief but extremely high current on power up to charge the mains capacitors...and of course transformers also have inrush, but of an inductive nature. Having worked on arcade games, and seeing how arcades operate, here is my theory on why this burned up: They used that breaker to turn ALL of the games (and/or lighting) on and off at the same time, instead of using the individual circuits. The combination of capacitive inrush, combined with inductive inrush (and resulting capacitive/inductive currents creating resonate overvoltages) finally hit critical mass and blew it up. Even a standard Non-RCD breaker's contacts will fail with such abuse. I have had to replace many breakers in arcades for this very reason. If the viewer who sent this to you is reading this: Tell the arcade to change their daily routine or it WILL happen again.
That's highly probably. And not helped by the high current to the degaussing coils at power up on the older games too.
I have had this exact problem on a high in rush load circuit that a breaker was used as a on off switch for. Repeated use leads to it over time weakening the breaker until it eventually welds itself like this. The solution was to put the load on a MDU that turned on in a staggered way
Great autopsy, some people think resetting; is holding it in the on position for several seconds, even though the mechanism is trying to switch off.
Thankfully standards, and better training/certification for electrical installers has greatly improved since my first foray into domestic installations circa 1970's. But idiots do breed ( rather well, if truth be told).
My best story of attending a customer, was being called to a lady's house, who complained that her new TV picture was smaller than it should be ( Vacuum set), her TV supplier said it was fine. Within a few seconds, the cause was obvious, the surface socket of round pin 5 amp type, had been wired directly to a 16 amp fuse with "Bell Wire " having a current rating of maybe 3 amp max). Lucky, the lady didn't own a vacuum cleaner or electric fire ( this was the only socket in the room) or there would have been a lovely burnt pattern under the wallpaperd wire.
So, a new 13amp socket, wired in 2.5 T/E channels with steel capping, and she had a nice full screen picture. In asking who had installed the unsatisfactory item, she said it was a friend of the family who worked for the local electricity supply company ( MEB - Midlands Electricity Board)!!!, Asking around, it transpires that this was true, but his job was digging holes!!!.
Quality of electrical training peaked in the 80s. It's been in decline since. You can now go from zero electrical knowledge to a fully certified electrician in one week.
bigclivedotcom , I agree. It should be law that any trades person, Electrical, Plumbing, & Building etc should be regulated/licensed to work on/in on any property when providing a service, for larger projects, some semi-skilled labour is allowed.
Enjoy the channel, and learning electronically stuff, especially the inventive Chinese products, very inventive, especially with over a million university qualified graduates per year.
That plunger would have been buzzing so fast just before this blew.
"JW Here.." Best part :). Good grief, What a mess!! Is this from a reputable manufacturer?
Prominent brand here.
Hager is also very common in Germany. Yes, they have a good reputation.
As long as people aren't tearing these things apart and becoming incensed at their shortage of failure modes during a fault, the reputation will be based solely on the lack of escaped soot.
Which BtW I think they try auspiciously to contain rather than implement any backup plan.
breaker idea: get a slightly beefier SCR on that RCD output, and on trip, just short the output of the breaker. that way you can simplify the mechanism since the short circuit will fire the overcurrent solenoid, and it might even be safer since it practically instantly crowbars the output to / close to 0V with no mechanical delays.
although, I'm guessing breaker manufacturers know what they're doing and an SCR that could survive that load would be impractical
That type of cirquit is found in almost all high power audio amplifiers with mor than 1000W per channel as DC protection. Smaller ones use an relay to disconect the output, but above 20A the relays get impracticaly large. And yes they are an one shot device, shorting out from the massive current surge provided by the defective output stage.
That's a neat lock out.
So, to prevent electric shock, when a ground fault is detected, melt down the entire breaker panel. When the copper bus bars melt, power is lost to all circuits terminating in the panel. Rendering all circuits safe. I never thought of those bus bars as fusible links.
Very scary to use those breaker failed to trip
The problem with circuit breakers is folk switch them back on without 1st switching everything down stream off, reducing the load from the contacts.
That switch had been repeatedly reset over time resulting in wearing the contacts out.
Wonder if they are now wearing the new breaker out instead of tracing the earth leakage fault?🤔 🤠
I need one of those breaker locks. I often have service calls in assisted living building and If I shut a breaker off to work on a range or dishwasher, it seems someone always wants to turn it back on.
You can get universal ones on eBay that clamp onto the switch with a screw.
Good to know! Now maybe I will stop getting 240v shooting up my arm!
But lockout tagout takes all the excitement out. Health and safety gone mad.
Having witnessed an angry joiner storm into a distribution room of a building nearing completion and rip all the tape off the breakers and turn them all on, you have to allow for complete idiots.
Holy crap! Did that lackwit get anyone hurt?
I'd say you have to find a way to put destructive murderers to prison before they get a job where they can do that.
Instead of tape on the breaker, run the live up to the handle. Keeps those pesky fingers away, eventually.
ya lol, just connect mains to the door of the breaker box. Lifehack
hope they fixed the issue in the circuit it was feeding, something clearly wrong there. then again maybe a lightning surge harmed the device and made it randomly trip..
afterthought, maybe they used the thing as a "daily power switch" which breakers are not meant for! I've seen that kill many.
by 6:50, that had to be a direct or nearby lightning strike with huge voltage and surge currents. I'm betting it arced from the wire passing through sense coil to the control circuit and up stream as it tripped. I've seen many GFCI outlets look the same way from direct power line/pole strikes ( above ground electric here) lost random devices all over my own house in the past, it hit the whole street of people randomly killing devices also.
In parts of the world where UL standards govern, breakers can be designed to be used as a power switch for lighting circuits and are marked SWD, for "switching duty".
Kind of gives a new meaning to exploded view
This is a good example of over thinking a simple fuse
A Fuse can never protect you against most of the faults this can. Plus it can be reset.
Nope, MCBs, RCD's and RCBOs have no doubt saved hundred's of lives in the UK alone. At the end of the day it failed, but it failed safely - as it was designed. This issue was most likely due to it being operated outside of ints intended design parameters (100 or so actions in its lifetime).
If a rewire-able fuse had been fitted, I'm sure someone would of over-rated it by now and we could be talking about a building fire with loss of life.
Edward - Clive said it was from an arcade, so most likely they were shutting the machines down every night and turning them on with it and getting large inductive loads from older machines and tripping.
You know the rest of the story. Click, *trip, click, *trip, click, *trip, click, *trip, click *BANG.
In your discussion of CRTs and degaussing coils, you mentioned a temperature-dependent resistor that would limit the current when it got hot... I've seen super-cheap CRT driver circuits that used a small *light bulb* for that purpose, believe it or not. Works great until years later when the light bulb filament burns out...
My Rockola jukebox uses a lamp in series with the selector motor to act as a DC brake controller. Sudden high current burst and then fading off to protect the motor.
I wonder what happens to the IC when the fault current is so large? Could the transformer-coupled voltage (sense voltage) be large enough to damage the IC and cause the triac to stay on until "bang"?
Good question. At first I thought, surely it would have zener diode protection on the transformer´s outputs. But it doesn´t look like it.
I guess they´re relying on that signal never getting that big, which is probably fine since other components would fail first if there was this much fault current.
I am happy with that lock out equipment. I work allot with lockout tagout on work because of safety.
i would hazard the welded contact meant the solenoid trip circuit was running full time when it is only rated to for a very small duty cycle as it kills it's own supply. The solenoid heated up , melted wires and caused all manner of secondary smoke.
Great tear down and expaination of what went wrong, maybe the simpler circuit would be better in the long run.
My doorbell button stuck on one day when a package was delivered and the same thing happened to the solenoid: it melted. I came home to my entire house smelling like burnt coil windings. Thankfully it didn't start a fire. The step down transformer in the garage was fine but oddly enough I don't think it ever tripped the breaker.
I've seen some contactors , fuses , triacs and thyristor blow but never actually a RCD / GFI DR ( PT_PT Disjuntor Residual ) blowing this violent. That must be some on / off events, arc's passing enought energy to weld the joints. Must be some sort of surge load such inductive load ( pump motor) and the thyristor is not snubbered properly for that appliance, even that has the right class
It was so much simpler in bygone days when you could just put a penny behind the glass plug fuse. And we really did do that.
What also works in a pinch is sections of 1/2" copper pipe where the cartridge fuses would normally go. Instant upgrade from a 100
amp fast-acting fuse to a 20,000 amp time delay. I'm talking about NEC/CEC switchgear.
@@briangrainger2264 "20,000 amp time delay" LOL
I'd have thought that large PF Correction Caps are more likely to have large or excessive in rush currents.
it let out all of it's magic smoke!
I used to have hair clippers that would almost always pop the GFI in my bathroom when I switched them off. The device was "double-insulated" (no ground/earth prong) but had a polarized plug. I guess it was a residual magnetic field collapsing and inducing current over the neutral line?
It may have been the inductive voltage spike causing an over sensitive breaker to trip or quite possibly another faulty appliance or bit of wiring to arc over briefly if the live and earth connections were very close.
No other appliance was attached to the GFI. And it was always when I switched the clippers off. I never saw any arcing, but that could have been my own lack of observational prowess. ;)
I've had that happen a few times at my place, except it happens on rare occasion (about twice a year) when one particular LED lamp is turned on. Reset GFCI and it works fine ... weird!
My mother complained about a sensitive GFI that would trip when she shut off her hair dryer...I suspect something similar was occuring to what you are describing. Anyway, the GFI was original to the house so I simply replaced it and that solved the issue. If it has a similar design to the 4141 that Clive showed, I suppose its possible the delay caps have failed after 15 years and instead of providing a delay it simply lets the SCR fire instantly.
I have hair clippers that do the same thing. I rarely use then these days but when I did use them the GFCI outlet they were plugged into would pop sometimes when I turned it off.
Hmm a saying at a factory i worked at: 'If it's brown it's cooked, if it's black its fu*ked'
It was for motor windings, but it seems to apply here too lol.
It should have had more ventilation slots, there were not enough to let all the smoke out!
Grrrrr.......LOTO......pain in the bum. Interesting video. I knew there was degaussing coils in old crt's but not how they worked, though the more I think on how crt's work it does make sense. Still, learned something new. Nice
And that breaker is properly cooked !!....
Definitely gone with a nice bang 👍👍
The fault current must have been huge to weld those contacts.
Dead short on the 277 leg will smoke about everything. High voltage makes a lot of service companies a lot of money .
Btw tool for locking is a MasterLock S2391...
Yay a JW mention! Thanks for watching.
2:18 Don't say that Clive!! I've done it! 6mm bit straight through my hand! Had to put it in reverse to get it out! Bad memories.
I am happy that such electronic RCD s are not allowed in Germany, Austria and Switzerland. So our RCD (RCCB/RCBO) has mechanic/magnetic tripping unit. And so fare I have never seen a foult Like that.
I've heard a friend refer to the breaker lock as a lockout-tagout.
Lockout-tagout is jargon in the safety industry for the entire area of electrical isolation.
9:47 Even if you wire it in the "wrong way" the breaker will also break the current going thru the test resistor. So as long as the breaker isn't closed there will be no current going thru the test resistor.
Not on all breakers. Some have the test link wired from either side to avoid the issue, but many have the circuitry powered from the output side.
@@bigclivedotcom Interesting. But shouldn't that be considered as a flaw in the design? I mean you want your design to be as "idiot proof" as possible.
I have personally never seen one that doesn't go thru the breaker contacts, or at least haven't noticed it, then again maybe this is considered a safety hazard here and may not be sold here (Belgium).
Also most, if not all, RCDs sold here may be wired either way.
On a side note, in Belgium a circuit breaker MUST break all lines (live and neutral). In "older" houses we often have 3P 220V, which means that both wires of your 220V are actually live.