I have a couple tools I call breaker flippers, have to run them off a generator if I'm going to give them a hot supper because their operating current is higher than they should be drawing from a standard U.S. wall socket, they are also used to test generators to see how they handle temporary overloads.
@@lovotcore6946 haha, not a bad suggestion, but I know it's just cause I overdraw the current. I have two outlets in my whole shop. Adding two more circuits tomorrow!
@Blazin Redeye A "15A" abrasive metal saw will test your 20A breakers, so will an old "15A" Hitachi angle grinder, you will know it when you see it because the motor section looks like it belongs on a chop saw, it sounds like a saw on startup, and it's got more gravity in it than a plastic body tool should. The startup current for both is brutal, especially if the grinder has a cup wheel in it, that tests generators temporary overload behavior pretty well, either one will flip a 20A house breaker with heavy usage. The 2.5HP compressor is an even more aggressive temporary overload test for generators, but it doesn't tend to flip breakers when running.
@@QlueDuPlessis Assuming they've worked with Clive for more than a week, NONE of them would ever DARE show up for work within 3 Days of April 1st for fear of their very Sanity (and lives)...
Ah, excellent - yes, saw Chris's (CJR Electrical) video about this. One thing I love about UA-cam is the community atmosphere between so many diverse technical channels.
I've always been fascinated by RCDs, ever since I became a property manager and learnt what they were and roughly how they worked. I've been in a few situations where RCDs have saved the lives of people I know. Fortunately I've had no known deaths of tenants from faulty RCDs, so I'm glad about that. Thanks for the video, I found it quite interesting! Looking forward to seeing the burnt-out one.
Clive, I've enjoyed Chris's channel for awhile now. This is one of two videos I've seen where he said he was going to offer/send equipment to you to play with & diagnose.
back in the late 80s/early 90s there was a psychedelic techno artist who put out some awesome stuff (look up "No Idea" for a taste), called Earth Leakage Trip. I knew nothing about circuit breakers &co at the time and had a "whoa" moment a few years later when I got into electronics. the cover of the EP was a even b&w photo of a mains plug and socket but I didnt get the connection at the time
I saw a video from - I believe Applied Science - where an unsmoothened half-wave DC of the AC outlet voltage was needed (so AC rectified by a single diode). He mentioned that he was very careful not to toch the DC, because it might not trip the RCD. So if I understand it correctly, that is the case if you have an AC only RCD. Never thought about that. I don't test my RCD monthly. I have some Linux small board computers, like a firewall, who run in read/write mode. They don't like being powered off unexpectedly. If they are just writing some data to the SSD, files may get corrupted. So I have to shutdown them properly before I can test the RCD.
Did Chris do any sensible tests to try to find the tripping leak in that video ? Maybe he should have contacted (pun) an electrician ;) to find the wiring fault.
@@davenorth1265 That's my suspicions too - and is typical of today's workmen. Replace it whether broken or not. Take into account that he sent tit to BC to ask the question whether overload was the cause. An electrician would know it wasn't. My aunt's toilet wouldn't flush despite normal water in the cistern. Her plumber fixed the problem and unnecessarily replaced the float valve. A friend had a roof repair. The builder advised of another potential leak problem - and sure enough it leaked next time it rained. Pretty sure the builder caused it after his first repair to create more work.
@@davenorth1265 Actually he did do tests and there was indeed an earth-leakage fault in one of the outlets which he fixed (verified by re-testing), but iirc the RCD still kept tripping so he replaced it as well, after which all was good. It was way too small anyway for the load it had to carry.
"That can make them a bit sensitive to impact" . . . well there's the explanation, the kids in the house have learnt that a bang on the consumer unit trips the power off.
bigclivedotcom slightly disappointed it wasn’t showing signs of overload at all. I know when I tested the rcd with my Kewtech Kt63plus it failed on 3/4 tests and the one it passed on was a very high trip time. Definitely a few factors in the property rendering this rcd useless.
Check out SparkyNinja UA-cam video about Testing Hager RCCB/RCDs UPDATE, requiring a higher test current to achieve correct disconnection time. Fitting a type A RCD would not reduce tripping more likely to increase as the AC type may have been blinded by DC current and not operate in some situations. Strip MCB's out and fit Type A RCBO's is the way to go if the customer can stand the cost, however that may change when we have to fit AFDD's, Type F, EV,B,B+ RCD'S where will it end.
chris andrus - depends on the design of the hot water system, which also partially depends on the available mains water pressure. Where the hot water is provided by a hot water tank with cold water header tank (used to be extremely common in the U.K. in the past), the hot water pressure was far too low for a shower, and the capacity of the hot water tank would not support multiple showers. Hence if a shower was wanted to be provided, the easiest way is to install an electric shower, where the mains water is heated in the shower unit (mounted in the shower cubicle). Where the hot water system uses mains pressure for the hot water (and the system has sufficient hot water capacity available), then you won’t find any electrical showers.
@@Mister_Brown Not the showerhead. There is a box mounted on the wall with the heating elements in it. Clive has done a video taking one apart. The heated shower head ones are found in more 'third world' countries.
You had me worried there for a minute, but luckily all my RCDs are type A. Apparently type AC has not been allowed for new installations since 1996 here in the Netherlands.
@@bigclivedotcom only when installation guidelines are followed. even here i find many units with way more breakers on 1 rcd than allowed. even to the point that it makes me wonder why the main fuse is still working.
I do checking of that stuff regularly (german based) with specialized appliance tester/installation tester equipment. Judging from the setup and photo of the fuse box, I do not think that that RCD has been overloaded. Yes, the rated current in sum of all that RCCB is greater that 63A, but looking at the load behind that, it simply is unrealistic that they will draw that current over a longer period of time. Explanation: Usually cooking appliances will heat up for some minutes, but when the final temperature is reached, they will reduce the current draw resp. will give some short burst of energy every few seconds to maintain temperature. Same goes for ovens and that kind of stuff. As an example, where I did some measurements some time ago: You need about 0,5 kWh of Energy to boil some potatoes (one person meal...) in a pot in salted water. This takes about 20-25 minutes. Average value over time with 230 Volts=approx. 6 Amps. Even if you have 3 or maybe 4 platters going, you would not use 32A in average... Lighting is the same, so we don't talk about full throttle going on. Also the kitchen sockets usually are not used to full usage, so I would assume that sometimes that RCD has had a hard time going, but severe overload is different. A tripping RCD usually goes with leakage current going on, which can also occcur when lots of heating devices at the same time will do their thing- because some moisture between the coils generate some current path from L to PE and voila- you have your 15 mAmps that are sufficient to sometimes trip the breaker. At work we also use Hager RCD in our offices, and i found them to be quite fast- 20 ms tripping time and also near the low end of mAmps to trip them. A 30mA delta rated RCD is by standards allowed to trip at 15 mA, and has to trip at 30 mA.
Oh, wow. I just replaced one of these in my house. The RCD kept tripping randomly for a few years, but not too often. Then on the last occasion, it wouldn't reset, as it wasn't holding the contacts together tightly enough. I strongly suspect I still have leakage current somewhere, as the breaker for the top floor ring main also seems to trip sometimes. I don't have a proper clamp meter that will measure low enough, though, and don't really want to fork out £70 just for that one test. So I was going to suggest (to Clive) about maybe using the current transformer from the RCD to build a cheap leakage tester? Obviously it shouldn't be used for doing proper safety checks, but it could be made fairly accurate once calibrated against a multimeter. Or, I guess I could just break the connection from the ring main to the breaker, then shove the cheap "20 Amp" rated multimeter in series, but I'd rather not. lol
Side-note... When we last had an electrician here, to fit a Smart Meter (yeah, yeah, I know. lol), I asked him to install a full isolation switch for the whole distribution board / consumer unit. (which isn't a legal requirement in the UK, AFAIK, but he kindly fitted the iso switch anyway.) But interestingly, due to the RCD being on the left-hand side of the board (so the bus bar is on the lower-right terminal of the RCD), the Neutral wire from the incoming mains was hooked up to the left-hand terminal marked "L" on the RCD. AFAIK, this shouldn't matter, as the connections are in parallel inside the RCD, so as long as the Live connections stay on one side, and Neutral on the other, the specific RCD I bought should be fine. Obviously it's important to double-check that when replacing things, though. I made sure that the new RCD specifically stated that it didn't require a specific "polarity" for the connections, and pressed the Test button after installing the new one. Again, though with most RCDs of a similar design/type, you MUST keep the Live connections on one side of the RCD, and Neutral on the other. I just thought it was interesting to note. (The new breaker doesn't label the terminals specifically for "L" and "N" either.)
You could do a really cheap tester with a resistor (L to E)! If you chose the right value to give just under 30mA and it trips it would indicate eather an oversensitive RCD or an existing Earth fault!
@@totherarf True, I could just have a few different resistor values in a box, to do a ramp test. But I still need to determine which device or circuit is causing the problem. The RCD hasn't tripped for a few weeks now, so it's possible it was just the contacts in the old one heating up as well. It's just weird that the same breaker often trips at the same time, so that's probably worn out, too. I might just replace the whole consumer unit with a metal one. You can get the whole thing including a few breakers and two RCDs for about £80.
Just do an insulation test with 500VDC with a Fluke 1662 on a rainy Day. Before you test with 500 VDC, do a 250VDC runthrough and also messure N-PE first, before you continue to L-PE if N-PE was fault free. I am sure you can rent one for a Day. Good Luck.
Does the main switch capacity current be equal to the sum of the individual circuit breakers. The chances that all are on full capacity is slim. In my house (the Netherlands) the main breaker (from the provider) is 35 amps. If i add up all the groups circuit breakers together it comes to 128 A..
What are the main fuses of this building? The cables must be massive. Here in Sweden, a normal house has 400v 3x16A or 3x20A as main fuse. Mostly using 10A fuses for normal sockets.
Jakob Blomstrand they don’t supply houses with 3 phase here as most electricians would fuck it up with the dodgy ring mains.. competence isn’t learned in this country.. they buy it.
3x16 A or 3x20 A sounds small. In Finland it is either 3x25 A or 3x35 A with 3x63 A as an option but in many places that can cost up to 100 € more a month. In Helsinki they all are 5.51€ a month. New homes use 16 A on sockets, older ones have 10 A and can have lights on the same.
Interesting, thank you. Would the signal from the transformer be full-wave rectified before being applied to the solenoid? That would seem sensible if the residual magnetism in the solenoid has a specific polarity, as I presume it does. With full-wave rectification, why should tripping be more sensitive to one phase than the other? If half-wave rectification, why should it trip at all on the other phase? If no rectification, how does it work?
My house has an entire subpanel for the kitchen, my house was built in 1939 so we’ve needed to add various subpanels over the years we have a main panel that controls a lot of the replaced lines in the house, and we have a hall subpanel that controls all of the old wiring (knob and tube) and we have the subpanel in the basement that controls the kitchen.
4:00 where Clive asks why they don't just have one model of breaker at the higher rated current? It would be interesting to get hold of a couple and take them apart - maybe the only difference between them is the label on the front panel...
Don't know UK code, but in US, having multiple circuits that add up to more than the main isn't all that unusual. Sort of a 'duty cycle' thing. It'd be like saying, "Well what are the chances that both showers are in use at the same time someone is making tea in the kitchen and all the lights are on.... etc..." So although it could happen, the RCD current wouldn't exceed rated for very long and might only mildly heat up. And judging from the condition of those contacts, they didn't open under heavy load very often or ever. Love your video's BTW, watching you dissect things is a great way for me to get my 'tear stuff apart fix' vicariously. :)
Thanks Clive. Interesting to see inside an RCD. Did not know that RCD are not over current breakers. Explains a lot. Had a similar experience in a hospital theatre in Australia with an older RCD. It would trip on power up of a diathermy during its internal checking . The diathermy does a short internal high voltage/high freq (300volts 480khz) test. Turns out that the RCD was sensitive to HF leakage . The newer RCD replacement had no issues. Hospitals normally have 10mA trip current RCDs
Clive, I watched his vid the other day. Looks like he followed up and sent it to you. One of these days hopefully someone will send some breakers from the US for you to look at, especially a tandem breaker. It's not in the cards financially for me right now or I would go to the local big box home improvement shop and pick up a few of various types (brands are NOT interchangeable and different types between brands are NOT interchangeable as DIN rail systems are not used for residential panel boards here).
Practically speaking, no. Saturating the core can only decrease the inductance, not increase it. Since the high current winding already had a low enough inductance to pass mains AC without trouble, the effect you can get from saturating the core is minimal. However, you *can* saturate the core with a DC current through the high current winding, which causes the sense winding to stop responding correctly. This is the issue that Clive mentioned near the end. So you should be able to instead use the sense winding as a switch with the high current winding as a control. However, it's poorly constructed for that use since you'd both probably need a fairly high control current, and the useful current you can switch is going to be low due the regular ohmic resistance in that thin wire.
@@garbleduser It is a form of magnetic amplifier, however it is a differential amplifier, though it does saturate at high currents. Major difference between the 40, 63 and 100A versions is not the contacts, but the bigger permalloy strip coil wound in that plastic housing, as the higher current ones need a larger core area so that they do not go into saturation below the rated current, so as to keep the trip current the same. Permalloy is expensive enough for the manufacturer to keep the 3 stock units at a different price, even if the 100A covers all uses.
I had a RCBO keep tripping about 1 - 2 per week. I isolated each circuit "one at a time" and still it kept tripping.Then I replaced the RCBO and it hasn't tripped since. So I'm assuming that it was an oversensitive device??
Hey random question. When he calculated the current through resistor he just did voltage divide resistance. Ohm law. But don't have to do something with pf aswell like times result by 0.8? Or have I got a miss understanding.
@@bigclivedotcom so if factor in pf that would be peak avg. Think I need to read up again. Work on ships with split phase no neutral. Always equated in the pf. 🤦 Feel like student again.
Clive we have quite a few LED strip lights ect in my girls bedrooms and around the house. Would it be advisable to replace my breakers to include DC faults?
Change the RCD to a type "A" RCD they are all going that way now in UK because of LED lighting, and electronic SMPSU use in domestic & commercial installs now. DC on the mains supplies are becoming an issue now. Wait till EV charging comes in big time lol...
@@davey6024 With car chargers even type B could be necessary, depending on the type of car/charger. If enough DC leakage current (>6mA) flows to the car/charger, it could prevent a type A from tripping altogether, because it saturates the pickup coils.
Here in The Netherlands it's very common to have a large number of 16A breakers behind a 40A rated RCD. The main fuse is either 40A single phase or 25A three-phase so there is no need to have an RCD with a rating above 40A. Basically all breakers are always 16A, even for the lighting circuits. Chances that the water boiler, oven, washing machine, tumble dryer and dish washer are all heating at the same time is next to zero, but they can draw 16A each individually. If this situation would occur, the main breaker will trip and the RCD will still not see a significant overcurrent.
An oven/stovetop has only 6kW as Peak Power for a short time at heatup and it typically needs 3 Persons operating the 2 showers and oven/stovetop simultaneously, could be a rare case and only for a short period of time that this nominal overloading happened actually but not causing visible damage. Maybe even the setup of the RCD can sustain larger than 63A current when connected, as just the switching of the load is a larger problem
Yes, there’s a round permanent magnet on the top of the coil. The induced voltage cancels the magnetic field and releases the plunger, which trips the breaker
Clive, I have a socket and see dead circuit finder, I went to replace the battery and stupidly checked polarity on the PCB with the battery and probably blew a diode and it's dead now Do you want it?
In your older videos you could normally test 30mA RCDs without tripping your 100mA main.What happened that you need to use the neutral now not to trip it?
Okurka - depends on the circuitry, a clock that uses the mains frequency changes an internal counter every 20ms. A clock that uses a 32kHz crystal changes an internal counter every 31us...
MerryTrek - what, Brexit England do something sensible?! Not very likely me thinks... Would be fun if Scotland and Northern Ireland do dump the GMT/BST clock time zone change but England and Wales don’t!
What you said at the beginning confused me. If the RCDs are rated for 63A, they must be able to break that much fault current, right? What if it has close to its rated load running through it when a leakage to earth happens? It would still trip, and would have to break that current, right? I don't understand why you were saying it's just an isolator.
Do they run GFI circuit in your area? I'm curious. What I have learned, is if a breaker. It has been compromised. Should be replaced, because the next trip could be higher.
I saw that, what I found shocking was it took BT 2+ years to figure it out. Best RFI story I recall was interference on the uplink to an old TACS or maybe AMPS cell, turned out to be rusty diode effect from corroded screws on the door of a train carriage that passed by at different times.
Place where I worked, we had a lot of old-style electro-mechanical chart recorders fed from a circuit protected by GFCI (what we yanks call RCD's). When we replaced the recorders with solid-state electronic ones, the GFCI's started tripping a lot. We found that the newer recorders (since they have a lot of electronics and such) were equipped with heavy line-filters to ground to project them and these filter caps were drawing a fair amount to ground. Since the whole distribution panels were fed from conditioned power, we just clipped the line filter caps inside the recorders to solve it (not the best way I'm sure, but it solved our tripping problem).
This is a common issue in the entertainment industry. The electronic loads have to be broken down into a lot of smaller circuits. Which is a good thing to do anyway.
Question: Why is everything on an RCD? Is this standard UK code? Here in the US, only areas prone to leakage current (near water) get RCD/GFCI's: Showers, Kitchen sockets, pool equipment.
In the UK it's common to have two sections of the DB on a 30mA RCD each. But the option is there to have a combined RCD/GFCI and overcurrent device (RCBO) on every circuit. It provides extra protection against wiring damage.
Luis de Rivas - Yes, RCD protection is now required. We have moved from having individual sockets with RCD protection (typically only provided where an appliance used outside may be plugged in)(or plug in RCD socket adaptors) to having a consumer unit with a single RCD protecting all circuits, to a split load consumer unit with typically only the socket circuits on a RCD, and lighting and fixed wiring circuits on the non-RCD side, to split load consumer units with two RCDs, each protecting half the circuits. For a bit more money, increasingly, RCBOs are being used for individual circuits (these provide a RCD and a MCB in a single device). So for example in my consumer unit, I have a 32A RCBO for each of the 32A ring circuits (sockets), all the lighting is via 6A MCBs via a RCD.
In Finland we went in 10 years from no RCDs to everything on RCD. Before 1997 they were never required, then they were required on wet rooms and in 2007 on all. For grounding the same change took 67 years (from 1930 to 1997)
If it was only the clocks. Some Modern TVs, or just anything that pretends to be Smart does usually not cope too well with a sudden loss of power. In best Case it only takes ages to boot up again. I had situations where things lost their whole configuration. And I just figured out in a colleagues house, that TP Link Powerline Adapters and Wifi Repeaters set up their own little DHCP server because they boot faster than the router. No way to disable it, just have them boot with a DHCP server present...
The breaker will trip before any damage is done, so it's really only depends on your idea of ok🙃 The house I just moved to has a single 16A cirquit for the water heater, water pump and washing machine. Gets really annoying really fast.
I wonder if that small loop of "long wire" or the coil is responsible for these things tripping due to radio waves? I am a HAM radio operator and when I use my UHF radio (around 430-440 MHz), the shower trip flips every time. I have seen lots of posts online about smart meters tripping the RDC/GFCI. They usually send on mobile phone frequencies (around double that of UHF). I see absolutely NO RF shielding anywhere. It would be awesome to test one of those close to a cell phone to see if it trips. I bet it does. My appologies if you have already done a video about this as I am new to your channel. Awesome work! Respect - Gerald Magill B.Eng. in Electrical Engineering (Hons).
Was this RCD damaged by overcurrent? After tearing it into a million bits the answer is NO... Well thank goodness it wasn't damaged!!! Then Clive says "This RCD is not going back together again..." Yeah... Ya' think? LOL 😁 Anyway, we don't have that kind of electrical system in the U.S. I find these teardowns very interesting. Thanks Clive for showing us that.
I almost thought you were going to say rccb as in the ones on airplanes. They might have a switching power supply that the coupling capacitor from the low side to ground is on its way out to cause it to trip.
Tiny little magnet with a weak field in there, adjusted to get the correct field strength in the coil. In the top black protrusion, and turned to the correct trip current in the factory. This holds the armature just into position, so that the current through the coil is enough to reduce the field so the spring can release it. that is why it is in a small magnetic shield, as it is sensitive to magnetic fields around it, and without that shield it would be orientation sensitive due to the earth's magnetic field, and the current flowing in the busbars and wires near it. Circuit board is a pair of zener diodes to act as a voltage clamp, and some small capacitors to filter high frequency noise off the circuit. Likely yes the reason it was randomly tripping was DC in the system from half wave rectifiers and capacitive supplies, as they all have a small DC current flow from asymmetric rectification. This biases the permalloy sense coil into a non linear range and thus makes it act like a saturable reactor, so on one half cycle it will generate a current in the sense winding as it saturates, and randomly this current will be high enough along with harmonics to trip the coil.
Some clever engineering in RCD's I took apart a Wylex RCD as it failed RCD testing on my Kewtech KT65DL MFT, the sense coil was made of really fine layers of what looked like chromium leaves of flat wrapped material, strange...and it broke apart really easily.Still never figured out what it was lol. But it had similar minimal electronics like that Hager, just a few diodes and a resistor. Clever stuff! anyway, I replaced the wylex RCD and it tested out fine.
That would be Permalloy, wound into a flat tape toroid. Used because it has great permeability magnetically, and thin so there is minimal eddy current loss. Yes it is very brittle, and when you kink it it loses part of it;s magnetic ability. Used for many years as the premier material for audio heads till ferrite came into use because you could get the gap small, and it is cheap, but still in use for professional recorders today.
I was at an update meeting with a Hager rep last year (I think) and we were told that they are changing all of their 'standard' RCD's provided in split load boards to 100A rating, as generally that is the highest your cutout fuse will be and that is the only thing protecting the RCD should a fault occur with the RCD, that and to avoid this example of overload. I personally now fit RCBO boards where possible, much simpler when it comes to fault finding :)
I often use electric Installation Tester to measure different things. The measurement "loop impedance" can cause RCD-tripping. When i simply start the measurement between a Phase and the PE in a circuit with a RCD without changing the settings of the tester it would trip the RCD instantly. There is a function in the Tester to generate this DC current to saturate the Residual current transformer of a RCD to prevent tripping. Depending of the used Type of RCD you can set different options to block RCD's from tripping.
I've got a GFCI for each bathroom circuit. About once a year, one of them will trip for no apparent reason. It's so infrequent that I've never had an electrician check them out. You'd think that if there was really a problem, they'd trip more often. Maybe they're just getting old?
still right though - you could replace all 4 with the 100A type A. Why do they bother making and selling type AC any more either? I believe type AC is against wiring regulations in other EU country wiring regs due to how they can be rendered ineffective by pulsating DC currents.
@@millomweb Probably Type AC. Current ones have a pictogram on the front to indicate what type it is. Type AC has a sine wave in a rectangle, Type A has a sine wave plus a half-wave rectified sine wave.
If this is only rated for 63A, and it is not an overcurrent device, then are you supposed to not put more than a total of 63A of overcurrent devices on its bus? How else would you limit the current?
Star Gazer - the consumer unit will have a power company (or private building company) fuse between the supply cable and the meter, the consumer unit is wired to the meter. It’s normally good practice to have the switchgear rated at or above the rating of the power company fuse. The combined ratings of the MCBs is allowed to be greater because a diversity factor can be applied. It’s not likely that everything will be switched on at the same time. Although in this particular case, it does appear that the person who put this consumer unit in could have done a better job.
@@Mark1024MAK Thanks for the explanation. In the US, there's a main breaker inside the service panel to prevent overload in the event the total of the branch circuits do happen to exceed the supply rating.
It’s called diversity. Not everything will be running at the same time, and you should try to build the board so that both sides are equally loaded. It’s not impossible, but very improbable that both showers will be in use at the same time as the oven is heating up (not yet up to temperature, as the thermostat will cut it off) and four pans are heating up from cold. Plus there’s some tolerance built in, it takes everything some time to heat up to the point of tripping, and even more time to heat up to the point of causing damage. Also, the breaker rating is not the actual current draw.
I am wondering whether the RCD can actually sustain even larger currents than 63A when not switched, but just the switching of the higher rates is an actual problem for the contacts (so for example the extinguish capability of the resulting electrical arc)
@@mor4y Kingfisher Plc, it's an investment firm. They owned Comet, Superdrug & Woolworths before selling off what they believed to be non profitable parts of the group.
Why not use an Aus $14.50 MCB/RCD ( miniture circuit breaker / residual current device) on every circuit ? Why have separate circuit breakers and RCD's ?
What's the point of throwing two 40A shower breakers behind one 63A RCD. Won't the showers trip the RCD on over current all the time or are those 40A shower circuits grossly overrated for the actual shower units they connected too?
If I remember rightly, "core balance detectors", (RCD's) that were first introduced in Germany back in the early 1970's were of the passive type with a permanent magnet, the field of which had to be calibrated exactly to meet the 30mA trip point. The problems with the early permanent magnet type was the inevitable decay in the remnant magnetic field resulting in tripping at lower and lower imbalance currents but the outstanding hallmark being no electronics (SCR's, Triacs) and hence reliability and better immunity to tripping on transients. I don't like the modern electronic types at all and false tripping is a major issue especially with the cheap types that use high gate sensitivity SCR's as the switching element. I know of numerous people here in Australia that have lost refrigerators and freezers full of food whilst they were away on holidays due to RCD's tripping, usually the refrigerator or freezer has to be thrown out as you can never get rid of the smell. Due to the creeping "doctrinaire self righteousness" of modern "democracies", here in Australia RCD's legislation has been constantly changing from: no RCD's, to owner onus RCD's, to at least an overall RCD but with exemptions for refrigerators & freezers and life support systems to no exemptions to mandatory RCD's on all circuits and wired in from behind the main distribution panel so home owners cannot easily swap them out for just breakers or fuses. We had a tragic electrocution case in Western Australia two years ago where a little girl has suffered permanent brain damage (as well as other injuries) when the neutral wire to the house failed, because the neutrals and earths all come together on the main distribution panel using the MEN (multiple earth neutral) system the any RCD's (if fitted, I don't know if there were any) would not have detected the acive-neutral imbalance) The little girl was electrocuted outside the house touching a garden tap whilst standing on wet earth, obviously the wet earth presented a low enough path back to where ever the neutral was bonded to earth.
I'm not convinced that trip is being held by residual magnetism but is in fact hed by an 'over centre' spring akin to kettle trip bimetallic doodah arrangements.
I've had my share of nuisance tripping on RCDs. Interestingly I've used that very same RCD, it's actually fairly good quality (compared to the really cheap stuff), but still quite a bit cheaper than the really high end stuff (ABB). I discovered that modern appliances typically have surge arrestors and EMI filtering stuff in them that causes a small leakage to earth. If you have enough such appliances on an RCD, you get to the point where it's right on the brink. During times when we get rotational power cuts (known as load-shedding), it is quite common for the RCD to trip when the power returns after an outage. Backup inverters that have their own TN bonding relay also open the TN bond to test the relay (this is required by grid codes in many countries), and the act of removing the TN bond temporarily as well as passing a small DC test current through it all adds up to very frustrating and intermittent RCD tripping. That is when I learned about the various types of RCDs. There is type-AC (the one in this video) which is your traditional type, only really sensitive to AC leakage currents. Then there is type-A, which is better. Then there is a subset of type-A that has a small delay built in to avoid nuisance tripping on transients. ABB calls theirs "type APR", Gewiss calls it type IR (impulse resistant), Hager calls it HI (high immunity). These are quite a bit more expensive than a plain type-A, but must more affordable compared to what comes next. The next step up is type-F, and then type-B. These things are practically unaffordable. In my house I have the loads split over 2 RCDs (roughly 7mA standing loss over each one), and one of those RCDs (the one feeding computers and other switch mode supplies, things that traditionally have higher standing leakages) is an ABB type-APR.
Rotational power cuts sounds like some poverty shit. I can't believe it's being done in big US cities. Never a better time to turn on the AC and do some cooking than after a power cut.
TN-C and TN-C-S aren't novelties. In Germany it was permitted until 1973 (in East-Germany until 1990) to have a PEN conductor in final circuits, then this was changed that the PEN must at least have a size of 10mm² (copper) or 16mm² (aluminium). In the last version of the VDE 0100 were this was permitted, from the year 1969, the PEN should be connected to the earth-terminal of the outlet and from there a wire bridge connection to the neutral terminal of the outlet. The system is perfectly safe as long as there is no PEN breakage. This condition is a massive problem, because metal housings could become live at mains voltage. The most common systems here are TN-C-S and TT. But several DNO are now converting their TT-grid into TN-C-S, which is actually no problem for them. In case of this picture I can clearly determine how old this is, the combination black and green/yellow in a two core cable was only available between 1965 and 68: images.gutefrage.net/media/fragen/bilder/steckdose-anschliessen-mit-zwei-kabel/0_big.jpg?v=1544095332643 The outlet itself is not original, it was changed in the 1990s when screwless terminals for outlets came up. And actually it looks like someone didn't bother to install a box into the hole...looks like remnants of a hollow wall box are in there...
You are lucky in the UK that almost all the residential breakers are Standardized, here in the US there’s so many brands and profiles. Both of our subpanels are standard Square D but the main panel is an FPE (Federal Pacific Electric) and the breakers are outrageously expensive, it’s like $150 for a 20 amp breaker, although they do trip like they should. The electrician that we hired to wire the kitchen and some of the basement wasn’t the sharpest knife in the drawer, he put an outlet in the basement on the same circuit as the outlet for the microwave, and we have a very powerful microwave, it’s more powerful than most microwaves on the market, but I’ve found that if you run the microwave and a vacuum cleaner in the basement then the breaker will trip.
Had one RCD do odd things. Once it had a 20-30A load in it if you just switched on a socket with any appliance attached it would trip. It would pass an RCD test which is usually ramp tested. Got to the point of testing with a static leakage with a homebuilt device that could switch in 5mA at a time. At 35mA it still hadn't tripped. Usually you'd expect them at around 20mA to have gone. RCD swapped and never had a problem again since. No other leakage was found on the system past the background few mA - checked with a clamp leakage tester.
Would be interesting to do an overload test! Apparently they become unbalanced and more sensitive when overloaded which would make an split load boards safer for overloads.
Hi mate, you don't have to populate a C/U in order of load anymore. The thickness of the busbar renders that unnecessary. For sure the installer should have split the showers between the RCDs but it doesn't surprise me that the RCD is fine. It's quite new and an AC type. It's far more likely that the issue is related to items plugged in to the kitchen circuit. If he had tested properly no doubt he would have found the problem. Love your videos Clive!
I've had problems with RCDs tripping in circuits which use half wave rectification or poll the mains to use only one half of the sine wave. This results in the detector coil becoming magnetised rendering it more sensitive to leakage currents. With the Electric vehicle charger I first had this problem with we found that when thr battery reached 50% charge the charger halved its output power by only drawing power from the mains on the positive going side of the waveform. After about 15-20 minutes the RCD tripped and we measured the leakage current at 5mA, pretty much what was leaking from the whole house.
Because they're breakers are rated differently than our us ones. Like a 32 amp for a ring circuit. Because here in the US we just keep with the five or zero at the end of our breaker ratings for simplicity. But I think they have 63 amps. Because two ring circuits together would be 64. Since their standard power incoming is either 60 or 100 amp service. That would get to the maximum demand.
Chris Snyder - see en.wikipedia.org/wiki/Renard_series This gives us a preferred list of standard values. In the mainland U.K. most homes are provided with a single phase 230V (existing infrastructure is actually still 240V) 60A, 80A or 100A feeds. So older switchgear is often rated at 60A, 80A or 100A. Since then, most switchgear, fuses, circuit breakers etc. uses the Renard series (1, 1.25, 1.6, 2, 2.5, 3.15, 4, 5, 6.3, 8 and 10) unless a particular standard overrides this. Diversity then allows for a higher total of the fitted MCBs in a consumer unit compared to what you may expect. Although as Clive says, with a split load board, it should normally be evenly distributed between the two RCDs. Examples of where standards override the Renard series are BS 1363 plug fuses (available in 1A, 2A, *3A* , 5A, 7A, 10A and *13A* ratings, although only the 3A and 13A are preferred values, shops typically stock 3A, 5A and 13A). Similarly the standard for consumer unit MCBs allows unusual values like 32A.
Residences in Canada and the USA use 120V single phase mains while the UK uses 240V single phase. The higher Voltage means a device draws less Current (Amps) for a given Wattage. Watts = Volts x Amps (Amps = Watts / Volts) so a 100W bulb would draw 0.42A in the UK but 0.83A in Canada and the USA.
@@HappilyHomicidalHooligan actually most residences and small businesses in the US use 240 volt main which is split by a center tap into two 120 volt legs which operate in anti-phase to each other. This allows larger appliances like electric dryers furnaces and some machinery to be operated as 240 volt appliances.
Thanks you for always explain clearly and concisely the projects on your videos. Why do I need an isolation transformer? I recently purchased a $250 such, but I am afraid to let my young son use it. It will protect the scope,, but not his life. If he happens to touch both Live and Neutral on the workpiece then what? In my house I have 22 off MCB/RCD's on on each circuit. Can you please tell me why RCD isn't enough to save the scope, I know it will save the life from shock,,,tested it many times. Will 15 mA for a duration of say 30 m/seconds damage the scope? If not, then why use an I/T?
The isolation transformer will defeat the RCD because there is no path for current to ground. It protects the oscilloscope from that same path to allow probing of mains voltage equipment. I'd suggest letting your young son work with low voltage projects first until he is old enough to fully understand the hazards of mains current.
@@bigclivedotcom Many thanks for your reply and advice. I understood all you said but I didn't get the answer: will 15 mA for a duration of say 30 m/seconds damage the scope? If not, then isn't that 2 birds with one stone. I know the RCD will protect lives, that I have tested many times. Will it be possible for you to try what I am curious about,,, namely use a RCD for supply to the scope and the work piece??? again many thanks.
I find these devices so fascinating. The complexity is mind-boggling. And considering the intensive labor to assemble, the price is a bargain.
This circuit breaker ain't going back together again.
Now called a "Circuit Broken"
My shop breaker gets tested regularly! How it’s tested, I will not say, only that it’s doing it’s job. 😂
I have a couple tools I call breaker flippers, have to run them off a generator if I'm going to give them a hot supper because their operating current is higher than they should be drawing from a standard U.S. wall socket, they are also used to test generators to see how they handle temporary overloads.
@@lovotcore6946 haha, not a bad suggestion, but I know it's just cause I overdraw the current. I have two outlets in my whole shop. Adding two more circuits tomorrow!
@Blazin Redeye A "15A" abrasive metal saw will test your 20A breakers, so will an old "15A" Hitachi angle grinder, you will know it when you see it because the motor section looks like it belongs on a chop saw, it sounds like a saw on startup, and it's got more gravity in it than a plastic body tool should. The startup current for both is brutal, especially if the grinder has a cup wheel in it, that tests generators temporary overload behavior pretty well, either one will flip a 20A house breaker with heavy usage. The 2.5HP compressor is an even more aggressive temporary overload test for generators, but it doesn't tend to flip breakers when running.
@@lovotcore6946 ahhhh yes..
You must have the big floor sander 🤔
In the U.K. this is typically caused by a single phase air compressor with an M6 grub screw in the plug top fuse.
(shovels breaker bits into baggie and mails back to owner with note "Works perfectly fine.")
"No Fault Found"... ;-)
Shorts the output terminals internally and returns with note. " tested OK - reinstall".
Imagine being Clive's co-worker on the first of April. 😂🤣
@@QlueDuPlessis Assuming they've worked with Clive for more than a week, NONE of them would ever DARE show up for work within 3 Days of April 1st for fear of their very Sanity (and lives)...
As a software engineer I'd say "could not reproduce" and close the issue ;-)
Tripped accidentally; yeah, that's my story and I'm sticking to it!
Arrr, cosmic rays innit.
Me after I've been playing around with a couple of MOTs.
69 likes. Nice
Ah, excellent - yes, saw Chris's (CJR Electrical) video about this. One thing I love about UA-cam is the community atmosphere between so many diverse technical channels.
"Definite signs of sadness". Class. I might have to steal that phrase!
I've always been fascinated by RCDs, ever since I became a property manager and learnt what they were and roughly how they worked. I've been in a few situations where RCDs have saved the lives of people I know. Fortunately I've had no known deaths of tenants from faulty RCDs, so I'm glad about that.
Thanks for the video, I found it quite interesting! Looking forward to seeing the burnt-out one.
Clive, I've enjoyed Chris's channel for awhile now. This is one of two videos I've seen where he said he was going to offer/send equipment to you to play with & diagnose.
Super-Sensitive Magnetic Trip would be a pretty good bandname
back in the late 80s/early 90s there was a psychedelic techno artist who put out some awesome stuff (look up "No Idea" for a taste), called Earth Leakage Trip. I knew nothing about circuit breakers &co at the time and had a "whoa" moment a few years later when I got into electronics. the cover of the EP was a even b&w photo of a mains plug and socket but I didnt get the connection at the time
Screwfix is the most disappointing escort agency I've ever used.
Also the rape helpline wasn't what I thought.
@@barrybritcher "This is a crisis helpline for the victims, not a tips hot line" Were the words I heard.
I saw a video from - I believe Applied Science - where an unsmoothened half-wave DC of the AC outlet voltage was needed (so AC rectified by a single diode). He mentioned that he was very careful not to toch the DC, because it might not trip the RCD. So if I understand it correctly, that is the case if you have an AC only RCD. Never thought about that.
I don't test my RCD monthly. I have some Linux small board computers, like a firewall, who run in read/write mode. They don't like being powered off unexpectedly. If they are just writing some data to the SSD, files may get corrupted. So I have to shutdown them properly before I can test the RCD.
I saw Chris' video about this and was hoping for you to make the "follow-up" - interesting to see that the RCD was apparently fine!
Agreed, nice to see this UA-cam channel relay!
Did Chris do any sensible tests to try to find the tripping leak in that video ? Maybe he should have contacted (pun) an electrician ;) to find the wiring fault.
I wouldn't think he did any tests. Will have just decided that the problem is the RCD.
Very poor.
@@davenorth1265 That's my suspicions too - and is typical of today's workmen. Replace it whether broken or not. Take into account that he sent tit to BC to ask the question whether overload was the cause. An electrician would know it wasn't.
My aunt's toilet wouldn't flush despite normal water in the cistern. Her plumber fixed the problem and unnecessarily replaced the float valve.
A friend had a roof repair. The builder advised of another potential leak problem - and sure enough it leaked next time it rained. Pretty sure the builder caused it after his first repair to create more work.
@@davenorth1265 Actually he did do tests and there was indeed an earth-leakage fault in one of the outlets which he fixed (verified by re-testing), but iirc the RCD still kept tripping so he replaced it as well, after which all was good. It was way too small anyway for the load it had to carry.
"That can make them a bit sensitive to impact" . . . well there's the explanation, the kids in the house have learnt that a bang on the consumer unit trips the power off.
Very interesting thanks Clive.
Were you disappointed that there wasn't anything more conclusive?
bigclivedotcom slightly disappointed it wasn’t showing signs of overload at all. I know when I tested the rcd with my Kewtech Kt63plus it failed on 3/4 tests and the one it passed on was a very high trip time. Definitely a few factors in the property rendering this rcd useless.
Check out SparkyNinja UA-cam video about Testing Hager RCCB/RCDs UPDATE, requiring a higher test current to achieve correct disconnection time. Fitting a type A RCD would not reduce tripping more likely to increase as the AC type may have been blinded by DC current and not operate in some situations. Strip MCB's out and fit Type A RCBO's is the way to go if the customer can stand the cost, however that may change when we have to fit AFDD's, Type F, EV,B,B+ RCD'S where will it end.
A most excellent exploration!
Thanks Clive!
Hi Clive do you run a Q&A forum. I have a question about what the life is of an RCD. Are they meant to last? Or should they be replaced every so often
It took me a minute to realize that in the UK a lot of people have heated showers and that's why your showers use electricity😂
not heated showers, the showerhead is the waterheater
ohh thats why. i was also confused
About 8.5kw for an instant shower. I don't think two of those should be on the one board.
chris andrus - depends on the design of the hot water system, which also partially depends on the available mains water pressure. Where the hot water is provided by a hot water tank with cold water header tank (used to be extremely common in the U.K. in the past), the hot water pressure was far too low for a shower, and the capacity of the hot water tank would not support multiple showers. Hence if a shower was wanted to be provided, the easiest way is to install an electric shower, where the mains water is heated in the shower unit (mounted in the shower cubicle). Where the hot water system uses mains pressure for the hot water (and the system has sufficient hot water capacity available), then you won’t find any electrical showers.
@@Mister_Brown Not the showerhead. There is a box mounted on the wall with the heating elements in it. Clive has done a video taking one apart.
The heated shower head ones are found in more 'third world' countries.
You had me worried there for a minute, but luckily all my RCDs are type A. Apparently type AC has not been allowed for new installations since 1996 here in the Netherlands.
That puts you guys ahead of the UK in that area of safety.
@@bigclivedotcom only when installation guidelines are followed. even here i find many units with way more breakers on 1 rcd than allowed. even to the point that it makes me wonder why the main fuse is still working.
I do checking of that stuff regularly (german based) with specialized appliance tester/installation tester equipment. Judging from the setup and photo of the fuse box, I do not think that that RCD has been overloaded. Yes, the rated current in sum of all that RCCB is greater that 63A, but looking at the load behind that, it simply is unrealistic that they will draw that current over a longer period of time.
Explanation: Usually cooking appliances will heat up for some minutes, but when the final temperature is reached, they will reduce the current draw resp. will give some short burst of energy every few seconds to maintain temperature. Same goes for ovens and that kind of stuff.
As an example, where I did some measurements some time ago: You need about 0,5 kWh of Energy to boil some potatoes (one person meal...) in a pot in salted water. This takes about 20-25 minutes. Average value over time with 230 Volts=approx. 6 Amps. Even if you have 3 or maybe 4 platters going, you would not use 32A in average... Lighting is the same, so we don't talk about full throttle going on.
Also the kitchen sockets usually are not used to full usage, so I would assume that sometimes that RCD has had a hard time going, but severe overload is different.
A tripping RCD usually goes with leakage current going on, which can also occcur when lots of heating devices at the same time will do their thing- because some moisture between the coils generate some current path from L to PE and voila- you have your 15 mAmps that are sufficient to sometimes trip the breaker.
At work we also use Hager RCD in our offices, and i found them to be quite fast- 20 ms tripping time and also near the low end of mAmps to trip them.
A 30mA delta rated RCD is by standards allowed to trip at 15 mA, and has to trip at 30 mA.
Oh, wow.
I just replaced one of these in my house. The RCD kept tripping randomly for a few years, but not too often.
Then on the last occasion, it wouldn't reset, as it wasn't holding the contacts together tightly enough.
I strongly suspect I still have leakage current somewhere, as the breaker for the top floor ring main also seems to trip sometimes.
I don't have a proper clamp meter that will measure low enough, though, and don't really want to fork out £70 just for that one test.
So I was going to suggest (to Clive) about maybe using the current transformer from the RCD to build a cheap leakage tester?
Obviously it shouldn't be used for doing proper safety checks, but it could be made fairly accurate once calibrated against a multimeter.
Or, I guess I could just break the connection from the ring main to the breaker, then shove the cheap "20 Amp" rated multimeter in series, but I'd rather not. lol
Actually the RCD I have here is the Hager CD 284U, so the 100A version (30mA trip).
Side-note...
When we last had an electrician here, to fit a Smart Meter (yeah, yeah, I know. lol), I asked him to install a full isolation switch for the whole distribution board / consumer unit.
(which isn't a legal requirement in the UK, AFAIK, but he kindly fitted the iso switch anyway.)
But interestingly, due to the RCD being on the left-hand side of the board (so the bus bar is on the lower-right terminal of the RCD), the Neutral wire from the incoming mains was hooked up to the left-hand terminal marked "L" on the RCD.
AFAIK, this shouldn't matter, as the connections are in parallel inside the RCD, so as long as the Live connections stay on one side, and Neutral on the other, the specific RCD I bought should be fine.
Obviously it's important to double-check that when replacing things, though. I made sure that the new RCD specifically stated that it didn't require a specific "polarity" for the connections, and pressed the Test button after installing the new one.
Again, though with most RCDs of a similar design/type, you MUST keep the Live connections on one side of the RCD, and Neutral on the other. I just thought it was interesting to note.
(The new breaker doesn't label the terminals specifically for "L" and "N" either.)
You could do a really cheap tester with a resistor (L to E)!
If you chose the right value to give just under 30mA and it trips it would indicate eather an oversensitive RCD or an existing Earth fault!
@@totherarf True, I could just have a few different resistor values in a box, to do a ramp test.
But I still need to determine which device or circuit is causing the problem.
The RCD hasn't tripped for a few weeks now, so it's possible it was just the contacts in the old one heating up as well.
It's just weird that the same breaker often trips at the same time, so that's probably worn out, too.
I might just replace the whole consumer unit with a metal one. You can get the whole thing including a few breakers and two RCDs for about £80.
Just do an insulation test with 500VDC with a Fluke 1662 on a rainy Day. Before you test with 500 VDC, do a 250VDC runthrough and also messure N-PE first, before you continue to L-PE if N-PE was fault free. I am sure you can rent one for a Day.
Good Luck.
That's another good channel I watch...glad he caught that /before/ something had a meltdown.
I stopped watching him when the channel became a running advert for ITS.
Does the main switch capacity current be equal to the sum of the individual circuit breakers. The chances that all are on full capacity is slim. In my house (the Netherlands) the main breaker (from the provider) is 35 amps. If i add up all the groups circuit breakers together it comes to 128 A..
What are the main fuses of this building? The cables must be massive. Here in Sweden, a normal house has 400v 3x16A or 3x20A as main fuse. Mostly using 10A fuses for normal sockets.
Jakob Blomstrand they don’t supply houses with 3 phase here as most electricians would fuck it up with the dodgy ring mains.. competence isn’t learned in this country.. they buy it.
3x16 A or 3x20 A sounds small. In Finland it is either 3x25 A or 3x35 A with 3x63 A as an option but in many places that can cost up to 100 € more a month. In Helsinki they all are 5.51€ a month.
New homes use 16 A on sockets, older ones have 10 A and can have lights on the same.
Interesting, thank you. Would the signal from the transformer be full-wave rectified before being applied to the solenoid? That would seem sensible if the residual magnetism in the solenoid has a specific polarity, as I presume it does. With full-wave rectification, why should tripping be more sensitive to one phase than the other? If half-wave rectification, why should it trip at all on the other phase? If no rectification, how does it work?
Thanks Chris Cjr and thanks you Clive for the Tare down was very interesting
My house has an entire subpanel for the kitchen, my house was built in 1939 so we’ve needed to add various subpanels over the years we have a main panel that controls a lot of the replaced lines in the house, and we have a hall subpanel that controls all of the old wiring (knob and tube) and we have the subpanel in the basement that controls the kitchen.
I love how Tom is like the gold standard of electrician UA-camrs that everyone is compared to
He’s pretty good tbh
..."showing definite signs of sadness."😂😂😂
Awwww, it just needs a hug 🤗
A hug in an asbestos mat.
@@Agent24Electronics 😂 asbestos-you leave it alone👍
4:00 where Clive asks why they don't just have one model of breaker at the higher rated current? It would be interesting to get hold of a couple and take them apart - maybe the only difference between them is the label on the front panel...
Don't know UK code, but in US, having multiple circuits that add up to more than the main isn't all that unusual. Sort of a 'duty cycle' thing. It'd be like saying, "Well what are the chances that both showers are in use at the same time someone is making tea in the kitchen and all the lights are on.... etc..."
So although it could happen, the RCD current wouldn't exceed rated for very long and might only mildly heat up. And judging from the condition of those contacts, they didn't open under heavy load very often or ever.
Love your video's BTW, watching you dissect things is a great way for me to get my 'tear stuff apart fix' vicariously. :)
It's called diversity factor here. Based on not everything being in use continuously at once.
The old style wire fuses used to provide over current protection didn't they? Do we not have that anymore except for individual fuses in each plug?
Thanks Clive. Interesting to see inside an RCD. Did not know that RCD are not over current breakers. Explains a lot.
Had a similar experience in a hospital theatre in Australia with an older RCD. It would trip on power up of a diathermy during its internal checking . The diathermy does a short internal high voltage/high freq (300volts 480khz) test. Turns out that the RCD was sensitive to HF leakage . The newer RCD replacement had no issues. Hospitals normally have 10mA trip current RCDs
Clive, I watched his vid the other day. Looks like he followed up and sent it to you. One of these days hopefully someone will send some breakers from the US for you to look at, especially a tandem breaker. It's not in the cards financially for me right now or I would go to the local big box home improvement shop and pick up a few of various types (brands are NOT interchangeable and different types between brands are NOT interchangeable as DIN rail systems are not used for residential panel boards here).
If you put low voltage dc on the sense coil, will the core and the spot welded wires act like a saturable reactor?
I don't think it would make much difference to the current going through it.
Practically speaking, no. Saturating the core can only decrease the inductance, not increase it. Since the high current winding already had a low enough inductance to pass mains AC without trouble, the effect you can get from saturating the core is minimal.
However, you *can* saturate the core with a DC current through the high current winding, which causes the sense winding to stop responding correctly. This is the issue that Clive mentioned near the end.
So you should be able to instead use the sense winding as a switch with the high current winding as a control. However, it's poorly constructed for that use since you'd both probably need a fairly high control current, and the useful current you can switch is going to be low due the regular ohmic resistance in that thin wire.
@@bigclivedotcom It made me think of magnetic amplifiers.
@@Gameboygenius Wonderful response, thank you!
@@garbleduser It is a form of magnetic amplifier, however it is a differential amplifier, though it does saturate at high currents. Major difference between the 40, 63 and 100A versions is not the contacts, but the bigger permalloy strip coil wound in that plastic housing, as the higher current ones need a larger core area so that they do not go into saturation below the rated current, so as to keep the trip current the same. Permalloy is expensive enough for the manufacturer to keep the 3 stock units at a different price, even if the 100A covers all uses.
I had a RCBO keep tripping about 1 - 2 per week. I isolated each circuit "one at a time" and still it kept tripping.Then I replaced the RCBO and it hasn't tripped since. So I'm assuming that it was an oversensitive device??
Each brand has its quirks. Some are sensitive to vibration, and some are just over sensitive.
Hey random question. When he calculated the current through resistor he just did voltage divide resistance. Ohm law. But don't have to do something with pf aswell like times result by 0.8? Or have I got a miss understanding.
I calculated it as an RMS current value.
@@bigclivedotcom so if factor in pf that would be peak avg. Think I need to read up again. Work on ships with split phase no neutral. Always equated in the pf. 🤦 Feel like student again.
Clive we have quite a few LED strip lights ect in my girls bedrooms and around the house.
Would it be advisable to replace my breakers to include DC faults?
Change the RCD to a type "A" RCD they are all going that way now in UK because of LED lighting, and electronic SMPSU use in domestic & commercial installs now. DC on the mains supplies are becoming an issue now. Wait till EV charging comes in big time lol...
Today with so many SMPS in everything should be type A everywhere
Sad only few manufacturers have them in catalog
Hopefully they will become more readily available as car chargers become more common.
@@davey6024 With car chargers even type B could be necessary, depending on the type of car/charger. If enough DC leakage current (>6mA) flows to the car/charger, it could prevent a type A from tripping altogether, because it saturates the pickup coils.
Ah but, did it trip, or was it pushed?
Well, I've learned something today, and I'll bear that in mind if I encounter the same kind of issue.
Here in The Netherlands it's very common to have a large number of 16A breakers behind a 40A rated RCD. The main fuse is either 40A single phase or 25A three-phase so there is no need to have an RCD with a rating above 40A.
Basically all breakers are always 16A, even for the lighting circuits. Chances that the water boiler, oven, washing machine, tumble dryer and dish washer are all heating at the same time is next to zero, but they can draw 16A each individually. If this situation would occur, the main breaker will trip and the RCD will still not see a significant overcurrent.
Given ~8kW per shower, and around 5-6kW per stovetop/oven Id say it was potentially grossly overloaded depending on who was showering and cooking.
An oven/stovetop has only 6kW as Peak Power for a short time at heatup and it typically needs 3 Persons operating the 2 showers and oven/stovetop simultaneously, could be a rare case and only for a short period of time that this nominal overloading happened actually but not causing visible damage. Maybe even the setup of the RCD can sustain larger than 63A current when connected, as just the switching of the load is a larger problem
There may be a permanent magnet at the other end of the core and when the coil energises it may cancel it out?
Maybe the permanent magnet is on the bit that swings (e.g. N) and the coil produces another N and same poles repel !
@@millomweb maybe
Yes, there’s a round permanent magnet on the top of the coil. The induced voltage cancels the magnetic field and releases the plunger, which trips the breaker
Clive, I have a socket and see dead circuit finder, I went to replace the battery and stupidly checked polarity on the PCB with the battery and probably blew a diode and it's dead now
Do you want it?
I have tested my breaker near monthly, after watching the Technology Connections video on these.
In your older videos you could normally test 30mA RCDs without tripping your 100mA main.What happened that you need to use the neutral now not to trip it?
The original 100mA breaker became unreliable (failing to trip when tested). The installation now uses the more recent dual 30mA RCD arrangement.
Was that a wylex breaker that was on the recall a few years back?
It wasn't affected by the recall. It was the lower current ones.
you only need to test rcd's six monthly, i always find it is a good time to test them when the clocks change.
The EU voted to scrap clock changes from 2021 and it is thought that the UK will do the same...
Okurka - depends on the circuitry, a clock that uses the mains frequency changes an internal counter every 20ms. A clock that uses a 32kHz crystal changes an internal counter every 31us...
MerryTrek - what, Brexit England do something sensible?! Not very likely me thinks... Would be fun if Scotland and Northern Ireland do dump the GMT/BST clock time zone change but England and Wales don’t!
@@Mark1024MAK Now Imagine Ireland reinstating "double summer time", aka the Berlin timezone.
You don't 'need' to test RCDs at any given interval. It's just a good idea :)
Never knew Screwfix and B&Q owned by the same company, had to pause the video and go and look. Mind blown!!
love your work Clive :)
What you said at the beginning confused me. If the RCDs are rated for 63A, they must be able to break that much fault current, right? What if it has close to its rated load running through it when a leakage to earth happens? It would still trip, and would have to break that current, right? I don't understand why you were saying it's just an isolator.
It won't detect overcurrent on a load. Just leakage. The current rating is just for the contacts and internal wiring.
@@bigclivedotcom Right, but if there was leakage while a large current was flowing, it still trips, right?
@@AureliusR Yes. The fault trip current remains the same regardless of the load being powered.
Do they run GFI circuit in your area? I'm curious. What I have learned, is if a breaker. It has been compromised. Should be replaced, because the next trip could be higher.
We call GFCIs RCDs here. A good breaker should not be significantly compromised by tripping.
Whick is the new electrical system you mentioned that allows conding neutral to ground at 5:40?
It's not new. It was experimentally used several decades ago. It's not as safe as the more common ones used now.
@@bigclivedotcom Do you mean the TN-C?
Have you heard about the TV in Montgomeryshire causing the DSL to not function correctly? Would love to see a video about it on your channel!
I saw that, what I found shocking was it took BT 2+ years to figure it out.
Best RFI story I recall was interference on the uplink to an old TACS or maybe AMPS cell, turned out to be rusty diode effect from corroded screws on the door of a train carriage that passed by at different times.
Place where I worked, we had a lot of old-style electro-mechanical chart recorders fed from a circuit protected by GFCI (what we yanks call RCD's). When we replaced the recorders with solid-state electronic ones, the GFCI's started tripping a lot. We found that the newer recorders (since they have a lot of electronics and such) were equipped with heavy line-filters to ground to project them and these filter caps were drawing a fair amount to ground. Since the whole distribution panels were fed from conditioned power, we just clipped the line filter caps inside the recorders to solve it (not the best way I'm sure, but it solved our tripping problem).
This is a common issue in the entertainment industry. The electronic loads have to be broken down into a lot of smaller circuits. Which is a good thing to do anyway.
Question: Why is everything on an RCD? Is this standard UK code? Here in the US, only areas prone to leakage current (near water) get RCD/GFCI's: Showers, Kitchen sockets, pool equipment.
In the UK it's common to have two sections of the DB on a 30mA RCD each. But the option is there to have a combined RCD/GFCI and overcurrent device (RCBO) on every circuit. It provides extra protection against wiring damage.
Luis de Rivas - Yes, RCD protection is now required. We have moved from having individual sockets with RCD protection (typically only provided where an appliance used outside may be plugged in)(or plug in RCD socket adaptors) to having a consumer unit with a single RCD protecting all circuits, to a split load consumer unit with typically only the socket circuits on a RCD, and lighting and fixed wiring circuits on the non-RCD side, to split load consumer units with two RCDs, each protecting half the circuits. For a bit more money, increasingly, RCBOs are being used for individual circuits (these provide a RCD and a MCB in a single device). So for example in my consumer unit, I have a 32A RCBO for each of the 32A ring circuits (sockets), all the lighting is via 6A MCBs via a RCD.
In Finland we went in 10 years from no RCDs to everything on RCD. Before 1997 they were never required, then they were required on wet rooms and in 2007 on all. For grounding the same change took 67 years (from 1930 to 1997)
6:38 I don't test it that regularly because you have to set the time on the oven again, and the time on my alarm clock .....
That seems to apply to a lot of homes.
An other has posted that they test theirs 6 monthly - just before the clocks alter ;)
@@millomweb That is a BRILLIANT suggestion.
I have now put "Test RCDs" on the list of instructions for resetting every damn clock in the house and car
@@tararat It's not as brilliant as my first suggestion - abolish BST ! Leave the clocks alone - and those that want to get up earlier still can do!
If it was only the clocks. Some Modern TVs, or just anything that pretends to be Smart does usually not cope too well with a sudden loss of power. In best Case it only takes ages to boot up again. I had situations where things lost their whole configuration. And I just figured out in a colleagues house, that TP Link Powerline Adapters and Wifi Repeaters set up their own little DHCP server because they boot faster than the router. No way to disable it, just have them boot with a DHCP server present...
Nice the double winding thru the sense coil ring. But would it not easier (and uses less copper) to double the sense wiring?
That's actually very nicely built unit.
wow, those things are complicated, but cool. here we don't have any residual current breaker, only 80A overload, and that's that.
Interesting! My cooker and shower are wired into the same breaker. They are never in use at the same time, so that's ok isn't it?!
The breaker will trip before any damage is done, so it's really only depends on your idea of ok🙃 The house I just moved to has a single 16A cirquit for the water heater, water pump and washing machine. Gets really annoying really fast.
@Blazin Redeye sound like you're pretty well off by my standards
I wonder if that small loop of "long wire" or the coil is responsible for these things tripping due to radio waves? I am a HAM radio operator and when I use my UHF radio (around 430-440 MHz), the shower trip flips every time. I have seen lots of posts online about smart meters tripping the RDC/GFCI. They usually send on mobile phone frequencies (around double that of UHF). I see absolutely NO RF shielding anywhere. It would be awesome to test one of those close to a cell phone to see if it trips. I bet it does. My appologies if you have already done a video about this as I am new to your channel. Awesome work! Respect - Gerald Magill B.Eng. in Electrical Engineering (Hons).
All the Queen's horses and all the Queen's men couldn't put RCD back together again.
There was a recall on them wylex mcbs for burning. What’s the rating and batch code ?
The 32A one wasn't in the recall.
What’s to stop you using single way RCBOs for every circuit in the house?
Nothing.
Cost
Was this RCD damaged by overcurrent? After tearing it into a million bits the answer is NO... Well thank goodness it wasn't damaged!!! Then Clive says "This RCD is not going back together again..." Yeah... Ya' think? LOL 😁 Anyway, we don't have that kind of electrical system in the U.S. I find these teardowns very interesting. Thanks Clive for showing us that.
Don't have it in my house either, LOL !
I almost thought you were going to say rccb as in the ones on airplanes. They might have a switching power supply that the coupling capacitor from the low side to ground is on its way out to cause it to trip.
I wonder if you ha fired the demonstration so the supply was from the bottom feed as the norm if the result would have been the same?
Could that "smooshed up " wire have been inducing a magnetic field in the sense coil, as it was twisted into a loop and was right next to it?
Tiny little magnet with a weak field in there, adjusted to get the correct field strength in the coil. In the top black protrusion, and turned to the correct trip current in the factory. This holds the armature just into position, so that the current through the coil is enough to reduce the field so the spring can release it. that is why it is in a small magnetic shield, as it is sensitive to magnetic fields around it, and without that shield it would be orientation sensitive due to the earth's magnetic field, and the current flowing in the busbars and wires near it. Circuit board is a pair of zener diodes to act as a voltage clamp, and some small capacitors to filter high frequency noise off the circuit.
Likely yes the reason it was randomly tripping was DC in the system from half wave rectifiers and capacitive supplies, as they all have a small DC current flow from asymmetric rectification. This biases the permalloy sense coil into a non linear range and thus makes it act like a saturable reactor, so on one half cycle it will generate a current in the sense winding as it saturates, and randomly this current will be high enough along with harmonics to trip the coil.
Some clever engineering in RCD's I took apart a Wylex RCD as it failed RCD testing on my Kewtech KT65DL MFT, the sense coil was made of really fine layers of what looked like chromium leaves of flat wrapped material, strange...and it broke apart really easily.Still never figured out what it was lol. But it had similar minimal electronics like that Hager, just a few diodes and a resistor. Clever stuff! anyway, I replaced the wylex RCD and it tested out fine.
That would be Permalloy, wound into a flat tape toroid. Used because it has great permeability magnetically, and thin so there is minimal eddy current loss. Yes it is very brittle, and when you kink it it loses part of it;s magnetic ability. Used for many years as the premier material for audio heads till ferrite came into use because you could get the gap small, and it is cheap, but still in use for professional recorders today.
@@SeanBZA cool, I never knew that 😎👍
I was at an update meeting with a Hager rep last year (I think) and we were told that they are changing all of their 'standard' RCD's provided in split load boards to 100A rating, as generally that is the highest your cutout fuse will be and that is the only thing protecting the RCD should a fault occur with the RCD, that and to avoid this example of overload. I personally now fit RCBO boards where possible, much simpler when it comes to fault finding :)
I often use electric Installation Tester to measure different things. The measurement "loop impedance" can cause RCD-tripping. When i simply start the measurement between a Phase and the PE in a circuit with a RCD without changing the settings of the tester it would trip the RCD instantly. There is a function in the Tester to generate this DC current to saturate the Residual current transformer of a RCD to prevent tripping. Depending of the used Type of RCD you can set different options to block RCD's from tripping.
I've got a GFCI for each bathroom circuit. About once a year, one of them will trip for no apparent reason. It's so infrequent that I've never had an electrician check them out. You'd think that if there was really a problem, they'd trip more often. Maybe they're just getting old?
It can be something as simple as a bug strolling through a junction box.
I'd bet on condensation, there's a poorly located one in my kitchen that inadvertently gets splashed sometimes and trips itself a couple times a year.
What's the size of the DNO fuse on the incomer ?
I remember watching Chris’ video on thisn👌🏼 love the calculator BTW
On that Screwfix screenshot the top two are Type AC, the bottom two Type A.
still right though - you could replace all 4 with the 100A type A. Why do they bother making and selling type AC any more either? I believe type AC is against wiring regulations in other EU country wiring regs due to how they can be rendered ineffective by pulsating DC currents.
What type is it if the RCD doesn't specify ?
@@millomweb Probably Type AC. Current ones have a pictogram on the front to indicate what type it is. Type AC has a sine wave in a rectangle, Type A has a sine wave plus a half-wave rectified sine wave.
@@Graham_Langley That's my thought too.
If this is only rated for 63A, and it is not an overcurrent device, then are you supposed to not put more than a total of 63A of overcurrent devices on its bus? How else would you limit the current?
Put another breaker on the line that suppose to trip on overload condition
Not really, the addition is only reached never... so it's just fine. Although better balancing would be advisable.
Star Gazer - the consumer unit will have a power company (or private building company) fuse between the supply cable and the meter, the consumer unit is wired to the meter. It’s normally good practice to have the switchgear rated at or above the rating of the power company fuse.
The combined ratings of the MCBs is allowed to be greater because a diversity factor can be applied. It’s not likely that everything will be switched on at the same time. Although in this particular case, it does appear that the person who put this consumer unit in could have done a better job.
@@Mark1024MAK Thanks for the explanation. In the US, there's a main breaker inside the service panel to prevent overload in the event the total of the branch circuits do happen to exceed the supply rating.
It’s called diversity. Not everything will be running at the same time, and you should try to build the board so that both sides are equally loaded. It’s not impossible, but very improbable that both showers will be in use at the same time as the oven is heating up (not yet up to temperature, as the thermostat will cut it off) and four pans are heating up from cold. Plus there’s some tolerance built in, it takes everything some time to heat up to the point of tripping, and even more time to heat up to the point of causing damage. Also, the breaker rating is not the actual current draw.
You say usually the higher current ones are right to left but mine seemingly go the other way, you think I should change that?
It's not that critical. If it works, don't fix it.
@@bigclivedotcom oddly enough, its how I try and put them plugs in an extention cord...
I am wondering whether the RCD can actually sustain even larger currents than 63A when not switched, but just the switching of the higher rates is an actual problem for the contacts (so for example the extinguish capability of the resulting electrical arc)
It's rated to break a very high current. The rating is for continuous current. Possibly contact or wire sizing internally.
Just for audience clarity Screwfix ISN'T owned by B&Q, it's owned by Kingfisher Plc who own many hardware type business's throughout Europe.
And who owns b&q? 😉
@@mor4y Kingfisher Plc, it's an investment firm. They owned Comet, Superdrug & Woolworths before selling off what they believed to be non profitable parts of the group.
ZanderKaneUK - read en.wikipedia.org/wiki/Kingfisher_plc for the history...
@@Mark1024MAK still not owned by B&Q though? Yes I wasn't correct about timeline, but its essentially a investment/holdings firm.
Why not use an Aus $14.50 MCB/RCD ( miniture circuit breaker / residual current device) on every circuit ? Why have separate circuit breakers and RCD's ?
We do have RCBOs over here, but they have their own issues. Mainly jamming too much into a small case.
What's the point of throwing two 40A shower breakers behind one 63A RCD. Won't the showers trip the RCD on over current all the time or are those 40A shower circuits grossly overrated for the actual shower units they connected too?
The RCD does not have overcurrent sensing. That's its continuous rated current.
nice calculator Clive :D
If I remember rightly, "core balance detectors", (RCD's) that were first introduced in Germany back in the early 1970's were of the passive type with a permanent magnet, the field of which had to be calibrated exactly to meet the 30mA trip point.
The problems with the early permanent magnet type was the inevitable decay in the remnant magnetic field resulting in tripping at lower and lower imbalance currents but the outstanding hallmark being no electronics (SCR's, Triacs) and hence reliability and better immunity to tripping on transients.
I don't like the modern electronic types at all and false tripping is a major issue especially with the cheap types that use high gate sensitivity SCR's as the switching element. I know of numerous people here in Australia that have lost refrigerators and freezers full of food whilst they were away on holidays due to RCD's tripping, usually the refrigerator or freezer has to be thrown out as you can never get rid of the smell. Due to the creeping "doctrinaire self righteousness" of modern "democracies", here in Australia RCD's legislation has been constantly changing from: no RCD's, to owner onus RCD's, to at least an overall RCD but with exemptions for refrigerators & freezers and life support systems to no exemptions to mandatory RCD's on all circuits and wired in from behind the main distribution panel so home owners cannot easily swap them out for just breakers or fuses.
We had a tragic electrocution case in Western Australia two years ago where a little girl has suffered permanent brain damage (as well as other injuries) when the neutral wire to the house failed, because the neutrals and earths all come together on the main distribution panel using the MEN (multiple earth neutral) system the any RCD's (if fitted, I don't know if there were any) would not have detected the acive-neutral imbalance) The little girl was electrocuted outside the house touching a garden tap whilst standing on wet earth, obviously the wet earth presented a low enough path back to where ever the neutral was bonded to earth.
Screwfix is actually owned by Kingfisher which is the parent company of B&Q, Castorama (France) and Brico Depot (Poland)
Did you receive Jordans from an external car charger.
I'm not convinced that trip is being held by residual magnetism but is in fact hed by an 'over centre' spring akin to kettle trip bimetallic doodah arrangements.
I've had my share of nuisance tripping on RCDs. Interestingly I've used that very same RCD, it's actually fairly good quality (compared to the really cheap stuff), but still quite a bit cheaper than the really high end stuff (ABB).
I discovered that modern appliances typically have surge arrestors and EMI filtering stuff in them that causes a small leakage to earth. If you have enough such appliances on an RCD, you get to the point where it's right on the brink. During times when we get rotational power cuts (known as load-shedding), it is quite common for the RCD to trip when the power returns after an outage.
Backup inverters that have their own TN bonding relay also open the TN bond to test the relay (this is required by grid codes in many countries), and the act of removing the TN bond temporarily as well as passing a small DC test current through it all adds up to very frustrating and intermittent RCD tripping.
That is when I learned about the various types of RCDs. There is type-AC (the one in this video) which is your traditional type, only really sensitive to AC leakage currents. Then there is type-A, which is better. Then there is a subset of type-A that has a small delay built in to avoid nuisance tripping on transients. ABB calls theirs "type APR", Gewiss calls it type IR (impulse resistant), Hager calls it HI (high immunity). These are quite a bit more expensive than a plain type-A, but must more affordable compared to what comes next. The next step up is type-F, and then type-B. These things are practically unaffordable.
In my house I have the loads split over 2 RCDs (roughly 7mA standing loss over each one), and one of those RCDs (the one feeding computers and other switch mode supplies, things that traditionally have higher standing leakages) is an ABB type-APR.
Rotational power cuts sounds like some poverty shit. I can't believe it's being done in big US cities. Never a better time to turn on the AC and do some cooking than after a power cut.
You pulled out the sense coil and I thought "That is a beauty of engineering"
TN-C and TN-C-S aren't novelties. In Germany it was permitted until 1973 (in East-Germany until 1990) to have a PEN conductor in final circuits, then this was changed that the PEN must at least have a size of 10mm² (copper) or 16mm² (aluminium). In the last version of the VDE 0100 were this was permitted, from the year 1969, the PEN should be connected to the earth-terminal of the outlet and from there a wire bridge connection to the neutral terminal of the outlet. The system is perfectly safe as long as there is no PEN breakage. This condition is a massive problem, because metal housings could become live at mains voltage.
The most common systems here are TN-C-S and TT. But several DNO are now converting their TT-grid into TN-C-S, which is actually no problem for them.
In case of this picture I can clearly determine how old this is, the combination black and green/yellow in a two core cable was only available between 1965 and 68:
images.gutefrage.net/media/fragen/bilder/steckdose-anschliessen-mit-zwei-kabel/0_big.jpg?v=1544095332643
The outlet itself is not original, it was changed in the 1990s when screwless terminals for outlets came up. And actually it looks like someone didn't bother to install a box into the hole...looks like remnants of a hollow wall box are in there...
Take it to bits, Get ma spudger, One moment, please. All perfect toolbox stickers! Get it to it! Lol.
You are lucky in the UK that almost all the residential breakers are Standardized, here in the US there’s so many brands and profiles. Both of our subpanels are standard Square D but the main panel is an FPE (Federal Pacific Electric) and the breakers are outrageously expensive, it’s like $150 for a 20 amp breaker, although they do trip like they should. The electrician that we hired to wire the kitchen and some of the basement wasn’t the sharpest knife in the drawer, he put an outlet in the basement on the same circuit as the outlet for the microwave, and we have a very powerful microwave, it’s more powerful than most microwaves on the market, but I’ve found that if you run the microwave and a vacuum cleaner in the basement then the breaker will trip.
Square D, 50 years ago were an industry standard. No longer! Now Just crap!
All my kitchen sockets are on the same RCD, the cooker is gas however and that's ALL that RCD does.
Sounds interesting would like to see a gas RCD. 😀
Had one RCD do odd things. Once it had a 20-30A load in it if you just switched on a socket with any appliance attached it would trip. It would pass an RCD test which is usually ramp tested. Got to the point of testing with a static leakage with a homebuilt device that could switch in 5mA at a time. At 35mA it still hadn't tripped. Usually you'd expect them at around 20mA to have gone. RCD swapped and never had a problem again since. No other leakage was found on the system past the background few mA - checked with a clamp leakage tester.
Would be interesting to do an overload test!
Apparently they become unbalanced and more sensitive when overloaded which would make an split load boards safer for overloads.
Hi mate, you don't have to populate a C/U in order of load anymore. The thickness of the busbar renders that unnecessary. For sure the installer should have split the showers between the RCDs but it doesn't surprise me that the RCD is fine. It's quite new and an AC type. It's far more likely that the issue is related to items plugged in to the kitchen circuit. If he had tested properly no doubt he would have found the problem. Love your videos Clive!
I've had problems with RCDs tripping in circuits which use half wave rectification or poll the mains to use only one half of the sine wave. This results in the detector coil becoming magnetised rendering it more sensitive to leakage currents. With the Electric vehicle charger I first had this problem with we found that when thr battery reached 50% charge the charger halved its output power by only drawing power from the mains on the positive going side of the waveform. After about 15-20 minutes the RCD tripped and we measured the leakage current at 5mA, pretty much what was leaking from the whole house.
Clive why is 63 amp's seem to be some kind of standard we don't have that here in the US and I'm curious as to why
Because they're breakers are rated differently than our us ones.
Like a 32 amp for a ring circuit.
Because here in the US we just keep with the five or zero at the end of our breaker ratings for simplicity.
But I think they have 63 amps.
Because two ring circuits together would be 64.
Since their standard power incoming is either 60 or 100 amp service. That would get to the maximum demand.
Chris Snyder - see en.wikipedia.org/wiki/Renard_series This gives us a preferred list of standard values. In the mainland U.K. most homes are provided with a single phase 230V (existing infrastructure is actually still 240V) 60A, 80A or 100A feeds. So older switchgear is often rated at 60A, 80A or 100A. Since then, most switchgear, fuses, circuit breakers etc. uses the Renard series (1, 1.25, 1.6, 2, 2.5, 3.15, 4, 5, 6.3, 8 and 10) unless a particular standard overrides this. Diversity then allows for a higher total of the fitted MCBs in a consumer unit compared to what you may expect. Although as Clive says, with a split load board, it should normally be evenly distributed between the two RCDs.
Examples of where standards override the Renard series are BS 1363 plug fuses (available in 1A, 2A, *3A* , 5A, 7A, 10A and *13A* ratings, although only the 3A and 13A are preferred values, shops typically stock 3A, 5A and 13A). Similarly the standard for consumer unit MCBs allows unusual values like 32A.
Residences in Canada and the USA use 120V single phase mains while the UK uses 240V single phase.
The higher Voltage means a device draws less Current (Amps) for a given Wattage.
Watts = Volts x Amps (Amps = Watts / Volts) so a 100W bulb would draw 0.42A in the UK but 0.83A in Canada and the USA.
@@HappilyHomicidalHooligan actually most residences and small businesses in the US use 240 volt main which is split by a center tap into two 120 volt legs which operate in anti-phase to each other. This allows larger appliances like electric dryers furnaces and some machinery to be operated as 240 volt appliances.
Thanks you for always explain clearly and concisely the projects on your videos. Why do I need an isolation transformer? I recently purchased a $250 such, but I am afraid to let my young son use it.
It will protect the scope,, but not his life. If he happens to touch both Live and Neutral on the workpiece then what? In my house I have 22 off MCB/RCD's on on each circuit. Can you please tell me why RCD isn't enough to save the scope, I know it will save the life from shock,,,tested it many times. Will 15 mA for a duration of say 30 m/seconds damage the scope? If not, then why use an I/T?
The isolation transformer will defeat the RCD because there is no path for current to ground. It protects the oscilloscope from that same path to allow probing of mains voltage equipment.
I'd suggest letting your young son work with low voltage projects first until he is old enough to fully understand the hazards of mains current.
@@bigclivedotcom Many thanks for your reply and advice. I understood all you said but I didn't get the answer: will 15 mA for a duration of say 30 m/seconds damage the scope? If not, then isn't that 2 birds with one stone. I know the RCD will protect lives, that I have tested many times. Will it be possible for you to try what I am curious about,,, namely use a RCD for supply to the scope and the work piece??? again many thanks.
@@cookieboi4449 Most scopes are grounded. They should not have live mains circuitry probed.