Residual Current Devices (RCD) - How they work
Вставка
- Опубліковано 15 лип 2024
- An explanation of what RCDs are and how they work.
These have other names in other countries such as GFCI, however the principles are the same.
► Support this channel:
Patreon: / jwflame
PayPal Donations: xo4.uk/?PPP
► Social Media:
Twitter: / jwflame
Facebook: / jwflame
Instagram: / jwflame
► Contact info, sending stuff in: etc.:
xo4.uk/?YTT
► Website - More on this video and many other subjects
Website: www.flameport.com
Page for this video: xo4.uk/?RcD - Наука та технологія
This is what you get when someone who really understands what he's talking about makes video explanations: great videos.
Thanks.
Excellent explanation - finally someone not faking it, but actually knows what they are talking about. Thank you ever so much
Great to listen to an expert who speaks clearly with correct pronunciation. (very refreshing). Thanks JW.
Excellent!, I love the clear and comprehensive instruction in all your videos JW. Makes a refreshing change from the yadder on voluminously in the hope something remotely accurate is transmitted. Thank you.
Just stumbled across this video while I have been trying to figure out my intermittent RCD tripping. It has helped enormously, thank you.
Great video. Held my attention right through. Well done, could listen to you all day.
Thank you John, all your posts are informative and well presented.
Thanks for making these videos, I'm finding them very informative!
Brilliant, thorough and clear explanations in all the Vid's. Thank you JW.
excellent series of video's...
passed them to my apprentice
saves me time
thanks
Thank you! Nice clear explanation with diagrams for us visual learners! Much appreciated!
Thanks for another extremely good explanation, I learned a lot today.
Wish I had an electronics teacher like your good self when I was at school and I wouldnt have left with half the knowledge I needed and had to learn it again by myself later in life!
Always very interesting and informative videos!
Thank you so much for this! Clear and concise! Be well, be blessed.
This guy should be on the TV reading the news :-)
Great explanation....
What a wonderful video. Thanks John.
Thank you again john. I was hoping you would do a little more on 3phase RCDs , explaining the principle with a 3 phase only type and the ones with 3phase and neutral supply. It is always a pleasure to watch your videos.
I always knew what they did, now I know how! kudos to you sir.
Thanks for this video and all your others. They've been very useful to me.
Very informative videos! Well done!
thank great explanation. i couldn't explain it better myself
Wonderful explanation sir!!!! Thanks for share this information about residual current devices also known in us as GFCI
Great explanation! Thank you!
You helped me today John. Thanks.
Useful and easy understanding, you are so great.
Thanks for sharing RCD, now i really know what it does.
Thank you John, have always wondered how RCB worked, and have first hand experience a few weeks ago where the newly installed consumer unit RCD tripped due to 'rain water ingress' into a light switch. I dread to think what should have happened to us or to our home if we hadn't had the CU upgraded. Than you for the clear and concise explanation.
Hi John. Thanks for that great explanation on how RCD works. Your tutorials are so clear and simple to understand.
On a different note i would have also mentioned that RCD do have their disadvantage in that if for example the neutral wire was cut then the device would be rendered useless in operation and if someone was to touch the active to earth then they would receive a severe electrical shock. The unit would not cut out.....!
Just something i would have mentioned in your video.
Keep up the good work. Cheers
@Walter Hess No the circuit breaker wouldn't trip. You would fry just like an electric kettle jug element heating you like a natural lamp and toasting you red raw.
respect to your effort sr.
Thank you for your videos, very useful.
Hi! Greeting from Argentina. In my country we know it as "Interruptor diferencial" or "differential switch".Excelent video!!!
Your explanation is great
Thank you so much for the great informations in the video
thanks for posting this.
Very good clear information.
Great explanation I always wondered how it worked. In my house, it says RCCB rated 100mA made by Hager
In offices here, we use what we call "alamats" Which is the same thing as a RCBO it is a breaker with RCD included. Even some household installations use these.
John
That was very interesting and informative video.
I wonder if you could produce video on RCBO use and operation.
Thank you for all the hard work producing these video I have enjoyed watching them.
awesome explanation
Excellent. Masterclass.
brilliant channel bud
very good clear information
great stuff
simply good... thank you.😀
Thank you, John. We just performed a few home inspections in Greece. And we came across these RCDs. And we wanted the information you just provided. Where can we find information about location requirements for RCDs? For the U.S., we refer to the International Residential Code and the National Electric Code.
Thanks for your sharing 👍
The multiple earth neutral system is only used on land and small boats. In heavy marine applications they don't use the ships hull as an earth return because in marine applications that would cause a circuit breaker to trip and the electrical equipment to shutdown if one side shorted to the hull, also they do not want the hull to be a return path for electricity because it would cause metal electrolysis when shore power connections are made.
Yes I worked in crude oil tanquers an container ship vessels and there are not neutral in that's systems
i wish i found your channel and videos earlier amazing mate youve done a great job could you do a video explaining the breakers relationship to circuits and cable calculations and power factor ratios difference in three phases ad single and motors etc please much appreciated
haha.. I am so happy to see the BG's RCCB, Because we are the supplier in Wenzhou for BG.
great video.
nice videos . many thanks
Awesome info as usual!
I would like to ask if you could make a small video about properly grounding an outside TV antenna.
DVB-T is making its way to the rural areas here and I would like to install one but without the risk of a housefire in case a thunderstorm hits it :)
Many thanks in advance!
Had RCDs in four of the places where I've lived - there was just one, not on the lighting or heating circuits, in one place, another I think was the same. The next, none at all until the new shower was fitted and then only on the shower circuit. Two where I am now, with the lights and sockets being on different ones. My grandparents' house that they lived in for years had one fitted on a rewire in the 1980s - it frequently (but not always) tripped when my grandmother switched off the combination oven's socket, seemingly only if the oven was still warm, and it was "whole system" so it frequently meant a trip to the cupboard under the stairs in total darkness. Had they stayed there much longer I might have investigated - I suspect the socket was to blame as the same fault did not occur after they moved.
very good video
Nice one.
Would like you to comment/discuss the situation that nominally-latching RCDs (especially those from 1990s with single-RCD for whole-installation) that seem to operate fine, no nuisance-tripping, within current and time limits, have an annoying habit of tripping when outside power fails any any/much load attached. Have observed this with Wylex WSES RCDs for example.
Thanks a lot!
This guy is a genius. He really is.
Nice stick man J.W.
Reminds me of Kirchoffs Current Law ... the good ol' days of electronic engineering and electrical principles
Nice video boss
18:29 Residual Current Monitor or also called Line Isolation Monitor (LIM) .
Those devices have also a earth connection (earth is not connected to the installation behind this device)
and is only used for measure the impedance between each Live conductor (Phase or L1,L2,L3) and earth, and between Neutral and earth.
In short, this device acts like a Ohmmeter, but on a live circuit.
John would like to thank you for providing such good videos, is there any chance you could do a video on contactors?!
Yes, already underway.
great video john. dunno if u can help on installing into rcds , I wanna install new double socket & our rcd is right above the area I want the socket to be. is it matter of feeding new wires from the rcd to new socket down below? I can't spur off another socket becos the nearest one across the other side of the room.
thank you
Thanks Sir for this great video.
In fact, I know briefly the idea of work of the RCDs long time ago, but what brings me here is the confusion I am facing now and searching for an appropriate interpretation for.
The problem is that the RCD is supposed to sense the current returned from the neutral but the question is: what about the current consumed in the load? I mean, if the supply gives 2 amps and the load consumed 1 amps and converted it into heat or light .. whatever, should not I have only 1 amps returned current?
Also, I know from the university days that the neutral carries current only in case of unbalance. Of course the single phase distribution for homes out of the 3-phase source will ensure that there is a permanent unbalance in the system, but what I remember is that the neutral will return only the unbalance difference.
Finally, I would appreciate if you have experience in Operation Rooms safety and how the system of earthing to the PVC and the isolating transformers are related together.
Regards,
thank u sir
How about countries like the Philippines where sockets don't have a ground and the neutral/live can be on either pin, depending on which way you plug a two-prong lead into the wall? Can you still use these kind of plug-in RCD devices and get the same kind of safety? In another comment, you say an RCD can't work without a reference to ground but other sources online suggest it will still work.
Gadget Addict The RCD will still work, it does not require a ground connection at the socket. It just detects an imbalance between line and neutral caused by a fault to ground.
RCDs do require that the supply is referenced to ground, however virtually all electrical supplies are, usually at the transformer.
An RCD will not work on an isolated supply as there is no path for current to return via the ground - however in that case the RCD would not be needed as there would be no shock risk from a person touching either line or neutral.
Isolated supplies are rare, typically from some types of small portable generator or inverter.
***** Great, thanks for the reply John. I'm renting so swapping out the breakers or running new wires isn't all that practical. But replacing the sockets or buying plug-in RCD devices are :)
Well said and good video. I have a generator that puts out 6500 watts, should this be grounded? I run power tools and charge my battery up using it...
Thank!
Hi John, as a request, if you haven't covered this somewhere else already, wondering if you could do a vid on circuit discrimination/selectivity? Thanks
I almost fell asleep twice in the first 2 1/2 seconds but things really picked up
Hell Mr. John Ward, could you make a video to explain the functions of each component in RCCB, RCBO and MCCB?
Very good indeed. (RCP)
yes i design all parts for people to look at the many things what i have done. so i can learn you of things what i can do. so listing to the story are giving.
Ref statement at 20.04 - 100mA devices need LOWER earth loop impedance and are useful where leakage currents are higher, eg. main distribution followed by 30mA RCD at final sub circuits.
awesome
Hello JW, do you have any idea why bs7671 forbids using RCDs in TNC systems? I know that it's not a perfect protection but at least would increase the safety of old buildings which don't have any earthing and bonding.
hello john i enjoy watching your video's and i have learnt a lot,i have a problem now as i bought a 3500watt inverter not a cheap one and i had a transfer 3 way switch installed 1 being the grid 2 is off and 3 being my inverter/generator anyhow as soon as i turn the inverter on my new split load consumer trips i have 2 63amp rcd 30ma.It trips when i turn the downstairs sockets on the inverter as inlet and outlet 230volt and the inlet is turned off by the breaker in my garage where the inverter is mounted i also have a earth rod ground and all my equipment is grounded DO YOU HAVE ANY IDEA WHY thanks john
Hi J W , on the R C D ,there's a diagram on the face of it , it shows 4 poles with a broken line running through the middle, my question is how can you tell what side is the supply, and what side is the load? ,great video's ,I'm really enjoying, thanks Steve
Thanks.
Thank you, but Could you explain to me " what will happen when we touch the Neutral line ( load side)? is it still working fine familiar with we touch of the Live conductor(load side).
2/ when we change the load side, L(RCCB) is connected to N load, and N( RCCB) is connected to the L(Load). is it still working fine?
My understanding is that what we call an RCD in the UK in the USA they call a GFCI and as you say they monitor difference between live and neutral i.e current flowing to earth, they wont trip if an insulation breakdown is causing arcing between live and neutral. in the usa they have something called an AFCI (Arc Fault Circuit Interrupt) whiich can detect arcing between live and neutral. How do these work and how come we dont have such a thing in the UK?
Hello john
whether there are two CTs inside RCD connected deferentially means one CT connected at live conductor part(RCD) and other CT connected in neutral(RCD) and these both CTs connected to relay.
When leakage take place current flow to the relay.?
Please make a video on the working of Isolating transformer used in Hospitals.
Hello sir I am an electrician from Thailand. I would like to ask for information, according to the IEC standard, how long must the residual current circuit breaker be cut off?
I'm going to get a plug in type socket tester, they don't detect Earth/Neutrl reverse, I am not sure if this is a concern?
Some are a tenner and some are £20, is there a standard I need to check for before purchase?
UK 240 V domestic
Thanks John.
Great video. I think you have answered my question in a round about way. Just want to check.
This is the scenario
I'm building a 3D printer and adding a heater bed (keenovo brand) running a 2 wire 240v line to it ( separate cord on same domestic power to it.)
Would a RCD save my skin if one of the wires broke off and either touched the metal frame (may or may not be earthed) or it touched me?
I'm guessing I wold survive as there would be a amp difference and if it touched an earthed part it would also activate.
The RCD would trip in both circumstances.
However the primary method of protection should be the metal frame being connected to earth so that the fuse would blow / circuit breaker trip if a live wire contacts the metal frame. The RCD is there as an additional protection, not the only method.
ok i got a interesting question. I have a rcd on my fuse box and then the manual said i should install a rcd spur socket for the electronic underfloor heating. which i realized later i don't need as fuse box has one. But what i dont understand why does the main fuse box rcd trip when i pressed the t button on the spur switch for underfloor heating. Also i have outdoor garden rcd sockets which work fine when i press the t button. Another issue i have is when i connect the yellow 110v transformer the rcd trips sometimes ?
Hello Sir , initially really I'm very thankful of you for your very helpful video series , you present your nice videos look alike "sport events tellers" and sometimes understanding your accent is a little bit hard for none natives and specially a challenge for me, anyway I love British accent and by listening you my English listening skills would be improved as well...LOL... , could you please answer these questions , on 4:54(time of video ) in the book we have RCD and RCBO , it seems that RCBO is better than RCD because RCBO does somehow operation and in this way "save life of people" and also protect the devices such as TV and washing machines and so on , yes ?? So what is the difference between RCD and RCBO?? which one of them for home is better and most suitable ? each ones RCBO for TV and washing machine is needed separately ? each one should has which specifications/ amperage ? each RCBO can cover how many devices ? sorry a lot of questions !! I am contacting from Kiev in Ukraine and by answering my questions you will solve a lot of problems for me and at the same time it is a very big favor, Your fan , your supporter , Afshin Heydari
Hi john, would an rcd still operate if there was a cross polarity?
Excellent video, John. I've got several extension cables that have mains filters on them. Can these contribute in causing the RCD to trip? Thanks.
mtahirfilms They can, as filters usually contain one or more capacitors between line-earth and neutral-earth. The current which can flow to earth is limited to a small value by the filter design, but if many of these filters are connected to a supply from a single RCD, the combined current can be enough to trip the RCD.
Thanks John. We've had RCD trips for the last week or so. We're trying to find out what the problem(s) are. We've removed all the surge protected extension leads. We've pretty much removed everything from the wall sockets in the house. Is there a way to do some simple tests using a multimeter on the surge protected extension leads to see if they're ok?
Between RCD & ELCB which one is more reliable and safer to use?
I heard RCD is the upgraded version of ELCB, is that true?
ELCB can mean RCD - RCDs are current operated and ELCBs can also be current operated.
However ELCB is often used to mean older voltage operated types which will only trip if a fault occurs between line and the installation earth. They will not trip if someone touches a live wire or if the fault is between line and the actual ground..
Current operated types and RCDs will trip for faults between line and the actual ground so are far better, as they will disconnect if someone touches a live wire.
Voltage operated types have not been used in the UK since the 1980s.
*****
Oh I see, that's why RCD is preferable.
Thanks. :)
Hi John, if the value of Ampere does not trip on overload then what is the purpose of the value in selection of my installation 20A, 32A, 40A, 63A
It would like to see you do a presentation on how arc fault interrupters work. They're all the rage here in North America now; I don't know about the UK.
It's on the list to do. They are virtually unknown in the UK, although changes to regulations from 2019 recommends them for some situations.
Can you please tell me if it is possible to connect an RCD the other way around? I mean for simple circuit breakers it doesn't make any difference. Is that the case for RCDs?
Usually yes - but check with the manufacturer to confirm.
excellent video, is there any chance you could explain why a ECLB wont operate if someone is to touch the line conductor?
That depends on how much current is flowing when you touch the line.If its more than 30 mA,then it will switch,provided its a 30 mA device.And of course only on the line coming out of the device,not the line coming in.
Thats why in medical classes the line is protected with lesser mA devices,like 15 mA..And the Earth line has a lesser resistance to earth.Big big rods to earth.
Further to my remark about working on live cable supply to replace my old supply panel with a new RCDO protected panel my professional sparks has explained to me that the cut out fuse you mentioned is located inside my big 3 phase mains cable supply manifold. Instead he told me he worked live on the junction box he found already installed downstream of the meter to disconnect the old panel and connect the new panel using suitably insulated tools. I guess this was a sensible solution ?
meandmymouth Yes, it can be done that way. What is better all depends on the exact situation.
***** Many thanks again.
John could you tell me if its possible to add rcd protection to a 30 amp rewirable fuse that is housed in a metal wylex consumer unit. I was thinking that if the load went through a stand alone rcd outside the board and then was connected to the existing 30 amp rewirable that might work. Your thoughts please.
Mark
Yes that's fine - just take the line and neutral for the circuit through the RCD. Earth permanently connected as before.
John, on a related topic, what do you consider the best means of rigging a warning buzzer for when an RCBO trips? There's a possible water ingress in our garage circuit with the very heavy downpour a couple of days ago and it tripped but now appears stable. I would like to fit a warning device. What do you think of RCBOs with auxilary contacts in order to fit a buzzer/light? If I can actually find one, that is, as I can see it mentioned online but rather difficult to find...
Aux contacts are not likely to be available for domestic RCBOs or anything else intended for a domestic consumer unit.
Probably easier to use something which detects the loss of electricity, a random example: www.instructables.com/Power-Failure-Alarm-for-Freezer/
@@jwflame indeed, it's just that I have an aversion to devices that sit there consuming energy - even if a tiny amount - when doing nothing 99.99% of the time! The idea of a switch physically connected to an RCBO is more appealing from that point of view. When I designed a one-shot/extendable timer for the pond-fill solenoid valve I deliberately did it with a zero standby current with some jiggery-pokery.
In an off grid situation would I be able use an RCBO if I connected the neutral from the inverter to a ground?
+Grimfan dingo Yes, but before making such a connection check the inverter carefully, as some are already wired like that.