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.
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.
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.
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!
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.
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.
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.
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.
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.
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.
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 ?
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.
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
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?
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?
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?
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 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,
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 ?
Hi JW, Where is the practical use of RCDs having I∆n=0.3A / 300mA. Does it gives protection against electric shock.? Should it can be used for residential applications.?
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 :)
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.
You said 100 mA RCDs are used for systems with high earth fault loop impedance. If the earth fault low impedance is high then potential leakage current is lower and in such circumstances we have to use a more sensitive RCD, which will trip for less than 30 mA, right? Could you please clarify this?
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
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.
Hi john, Another question. On a caravan site we connect to a pillar with our connecting leads if, for any reason, the earth in the cable or the supply pillar lost this connection to earth would the contact to earth by the caravan legs be sufficient to trip an RCD in the van under the same circumstances as my earlier post.?
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.
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.
Have you a video explaining how an RCD can be used where the earth looop impedance is too high. Is this an acceptable solution in a domestic situation where you do not want to install a larger cable etc etc etc Thanks
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.
Hi John, I thought I understood how most protective devices operate and you have confirmed with your excellent presentation that I actually did, however, my thinking became skewed when reading some posts on a particular site. First I believed that an RCD was complimentary to a good Earth system. I was aggressively informed that RCDs did not need a good earth to operate safely so if there was faulty earth you would still be safe. I understand the differences in the systems you elegantly described, however, so called electricians on the site did not answer my question which was:- If there is no earth present at say an appliance and a fault occurred how would the RCD detect an imbalance if there was no path to an earth. I assumed the path would soon become a apparent when a person touched the the appliance then the RCD would trip on contact if other things were in place of course. However, from experienced this 30ma used to trip it gives quite a jolt and from other sources I understand can result in problems for people with heart defects. What is your take on this?
+John W The imbalance occurs when someone or some other earthed object contacts a live part, current then flows through the person/object into the ground. This does mean the person may feel a shock, but the RCD will limit the shock to a very short duration. Although a 30mA RCD will trip at that level, it does not limit the current in any way, so it is entirely possible for the current to exceed that significantly, which may cause problems for some people. However disconnecting the supply quickly (less than 200ms for a typical RCD) dramatically reduces the possibility of injury or death. Having an RCD is still far better than not having one, particularly with the prevalence of double insulated appliances which do not have any earth connection.
Thanks John I have been aware that 200ms exposure at 230v can cause heart fibrillation and affect pace makers in vulnerable people. I would never dream of using a system without a combination of the two and was startled by Electricians even suggesting RCDs could be regarded as safe without an Earth presence.
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.
Thanks, very informative. I've looked at my fuse box and noticed the bathroom wall fans are not on RCD, only my kitchen appliances are on RCD. That was very irresponsible of the electrician. I then checked the RCD test button and it does nothing. Time to call the electrician. The MCB/RCD combined switch you showed is a great solution for the bathroom fans, didn't know they existed. As a point of interest. If you test on live wire that is on RCD using a neon screw driver, such as in your other video, should that not trip the RCD switch since the human body will earth some of the current and hence will not return to the RCD unit thus causing an imbalance in current between the line and neutral?
A very good question. A majority of RCDs have a fault current rating of 30mA. Now 30mA passing through your body is described in 17th Edition Wiring Regulations as "10-15mA: Muscular contraction, can't let go. 20-30mA: Impaired breathing". Etc etc. Now using Ohms law, from John's video, the resistor was measured at 1.535Megaohms (1535000ohms) and John was using 250VAC (or there about), so the simple maths is I=VR (250V / 1535000Ohms = 0.0001628A) or 0.16mA. 0.16mA is 'barely perceptible, no harmful effects' so an RCD would not trip in this instance, you'd need another 29.84mA for the RCD to trip. -Andrew
copelandaa Thanks for that explanation and calculation. I forgot about the tolerance before it trips. But are you saying that the built in tolerance level is actually lethal if it doesn't trip?
chinacane 30mA can certainly kill someone, it depends on the exact circumstances. - and if someone contacts a live wire, the current can easily be more than 30mA even with the RCD - the current is determined by the impedance of the fault. The RCD only limits the duration of the shock, not the current.
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.?
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?
+Marius Ammann Newer installations (under 10 years) will have RCDs as they are required on virtually all circuits. Previously (10-25 years) RCDs were required for socket outlets only, and before that they were typically not used at all.
Hi Jon . How does RCD testing using a tester work, a tester for example inputs 2x and 5x voltage. ie how does it create the imbalance to earth? Thanks for the videos.
A tester simply has a resistor between the line and the protective earth. This creates the fault. This also means that a tester will not work if there is no protective earth. The test button on the other hand creates the connection between line and neutral bypassing the RCD so it does not need earth.
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.
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
Please can you clear up the loose cable argument you read about. I can’t see how a loose line or neutral can cause a trip surely total current flow will be balanced all be it unstable etc. Thank you for all you give to us in terms of education.
Thanks for the video, one question, it does matter how you wire the RCDs, the flow between blue and brown (life and zero) need to be opposite on the RCD. You cant just put the outside life and zero on the top contacts on the RCD, if I understand this correct.
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
my question to Mr Ward... does the earth connection can compensate for RCDs or vice versa??? what happens if both are existing in a appliance (e. g. geyser)? which one of them is the most important? thanks in advance....
I never really looked at an RCD before. I always assumed that they would work when they detect any current going through the earth but i suppose that would be dangerous if the earth was missing or had a faulty connection. So would i be relatively safe if i started to receive a shock from a mains socket that contains no earth? The RCD would see that some current is being used but not returning and thus trip my mains? I have been worried about many of my sockets not being earthed as it is a French house from the 70's. But since i have an RCD i should be safe anyway? What sized resistor should i use to test my RCD? If i touch a resistor from live to the floor of my house at some point that should trip the RCD 100Kohm?
RCDs don’t trip soon enough or with low enough current to protect you in all circumstances. 30 mA RCDs come pretty close, but electricity behind it can still, kill you if you’re really unlucky.
It is helpful video, thank you very much but I want to ask you some question: 1- how the current amount will be the same on neutral line back of load as phase line, in another words how the consumption of power will be on voltage or current amount ??? 2- how the transformer will be in one end 0V and the other end of transformer not effected and stay 230v when you connet the 0v end to the ground, although the two ends in the same wire??? I will be glad if you answer me
A transformer isnt just a wire with two ends.Its a coil and because of that there is a magnetic field.A magnetic field has always a zero and a live side.Even in Direct Current(DC)I hope i enlightened you with my poor English.
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.
Hi John, Great video. I am installing an electric shower in an upstairs bathroom and the consumer unit is downstairs. I have purchased a stand alone RCD which I want to install directly above the consumer unit as the shower cable goes up to the bathroom. Being A.C. does it mater which way round the power goes into the RCD ?. Obviously for simplicity I would like the power to go into the bottom of the RCD out of the top. Many Thanks...
+John Ward . Thanks for the speedy reply so late at night. The only difference I can see is that the internal circuitry of the RCD is powered down when tripped as they would now be on the "cold" side of the internal switch. Goodnight and thanks again.. Regards. Paul,
Hi John, want to understand what happened.... I switch the CB off for one circuit of a wall socket , other in use, and replacing the socket as it was broken, I think by mistake the N touched with the Ground, nothing happened, just the RCB went off . Is that because the returning current from other circuits ( all N are connected together in the panel ? ) found a shorter way to earth and caused an imbalance? Again No live on that circuit. Thanks
Yes, the neutral is still connected and due to current flowing in other circuits the neutral will have a slightly different voltage to that of the earth. Connecting the two together causes a small current to flow via earth instead of neutral, and the RCD detects this imbalance and trips.
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
You talked about imbalance tripping the RCB. So, with a 3 phase RCB trip if there are different loads on different phases (load imbalance), will it trip the RCB? Or, the zero sum rule is the real key and the RCB will trip ONLY when some current is leaked out to earth.
hi john. In my power box the active wire from my main switch- goes into the breaker- then the rcd- then into the house, rather than what seems standard; wire from main switch- rcd- breaker - then into house ..... is this ok? and I'm thinking if I put in another rcd for other breakers I will copy the existing rcd setup.. what do you think?
Doesn't matter, most consumer units are configured with the RCD first, but it will still work exactly the same the other way. Or use RCBOs which are the breaker and RCD combined into a single device.
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.
Making is when it is switched on, breaking when it switches off. If a load is connected there will be a high current pulse when switched on particularly with things like motors. If a fault occurs there will be a very large current flow for a short period. The contacts must be capable of connecting/disconnecting without being damaged by these current pulses.
Thanks for the RCD information. I live in a remote area with no mains supply. I have a solar panel set up with a converter giving 5 Kw max at 230 V. I installed the system myself and put in rings protected with 2 pole "trip" switches. The main input from the inverter passes through a Hager "Residual current device - int diferential". I assumed that this would protect people who touched a live wire and the circuit in case of a short. Neither of my cables is connected to earth hence both sides of the system are "live". Your video tells me that i got it wrong. What should I do? or where can I find the required information? I will be grateful for any help you can give.
Mac Mudie The RCD won't work, as there is no reference to ground. However this also means people would not generally get a shock from touching a live wire, unless a fault to ground has already occurred within the installation. There are various methods of protecting such installations, further info here: xo4.uk/x/ect178.pdf (PDF document).
Good video thank you I just got a 1500w inverter and was thinking of buying a plug in RCD for more safty. But now i see there is no point as it wont work thank you. saved me some money lol. Plus intresting video.
Videos are very good, but I'm dying to know what's the formula that dictates when and where In the video those copyright notices appear. They seem to just appear at random for 5 seconds for no discernable reason
Ok, the scenario with the Generator with having no fault current to earth doesn't result in an electric shock, but the 1 thing I really want to know is with wall power, if you touch just the active and you are standing on concrete floor with rubber boots on, will there still be a current path to earth? Also the rest of body is isolated so your not touching neutral or an appliance etc.
In theory no shock - but in reality it's more complex. All depends on how effective those insulated boots actually are, which will also depend on moisture, humidity and so on. There is also capacitance to consider, as an insulating layer between a live part and earth forms a capacitor, and the other possibilities of someone in that situation accidently being in contact with something else.
@@jwflame Interesting... thanks for info. It's just because at work there have been a couple electric shocks, mine was I actually had twisted a live conductor with no shock and it wasn't until I earthed myself I got a boot. The next 1 was a worker stripped a door heater back and it was live, 1 finger was on the metal of pliers and he instantly got a boot and he was standing 1 meter away from any earth with electrical boots on. (the heater is rubber outer so it is not earthed) I know electric shocks should never happen, but its complicated when you know the circuit breaker, but somewhere along the repair the active accidentally gets put of a different circuit. Always gotta re-test...
Hi JW! Great content. I installed the RCD and now I have a question: how can I test and be sure that it actually works? When something bad happens with the washing machine in the bathroom how can I be sure that the RCD will switch off? 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!
excellent explanation, I have a question on another topic, I hope you can help me, I have a pool pump that works with 2 wires 220V, 110V per wire, (without neutral), would you recommend me to put a differential circuit breaker? If your answer is affirmative, how would it be, since the circuit breakers bring phase and neutral, I would need a 3-wire circuit breaker (2 phases and 1 neutral) where I connect the output neutral, if the pump only requires 2 phases (110V), , waiting for your attentions, thanks a lot
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?
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.
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.
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.
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.
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.
This guy should be on the TV reading the news :-)
Great explanation....
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 John, all your posts are informative and well presented.
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
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 so much for this! Clear and concise! Be well, be blessed.
What a wonderful video. Thanks John.
Hi! Greeting from Argentina. In my country we know it as "Interruptor diferencial" or "differential switch".Excelent video!!!
Thanks for another extremely good explanation, I learned a lot today.
Thank you! Nice clear explanation with diagrams for us visual learners! Much appreciated!
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
I always knew what they did, now I know how! kudos to you sir.
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.
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.
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.
Great explanation I always wondered how it worked. In my house, it says RCCB rated 100mA made by Hager
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.
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.
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.
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 informative videos! Well done!
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
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.
Thank you so much for the great informations in the video
Reminds me of Kirchoffs Current Law ... the good ol' days of electronic engineering and electrical principles
Useful and easy understanding, you are so great.
This guy is a genius. He really is.
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?
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?
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?
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 for this video and all your others. They've been very useful to me.
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,
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 ?
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
Hi JW,
Where is the practical use of RCDs having I∆n=0.3A / 300mA. Does it gives protection against electric shock.? Should it can be used for residential applications.?
Protection against fire
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...
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.
You said 100 mA RCDs are used for systems with high earth fault loop impedance. If the earth fault low impedance is high then potential leakage current is lower and in such circumstances we have to use a more sensitive RCD, which will trip for less than 30 mA, right? Could you please clarify this?
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
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.
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.
respect to your effort sr.
Hi john, Another question. On a caravan site we connect to a pillar with our connecting leads if, for any reason, the earth in the cable or the supply pillar lost this connection to earth would the contact to earth by the caravan legs be sufficient to trip an RCD in the van under the same circumstances as my earlier post.?
+John W In most circumstances yes - however not guaranteed as it all depends on the condition of and type of surface the legs are in contact with.
+John Ward Thanks John and understood.
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.
Your explanation is great
haha.. I am so happy to see the BG's RCCB, Because we are the supplier in Wenzhou for BG.
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.
Have you a video explaining how an RCD can be used where the earth looop impedance is too high. Is this an acceptable solution in a domestic situation where you do not want to install a larger cable etc etc etc Thanks
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.
Hi John, I thought I understood how most protective devices operate and you have confirmed with your excellent presentation that I actually did, however, my thinking became skewed when reading some posts on a particular site. First I believed that an RCD was complimentary to a good Earth system. I was aggressively informed that RCDs did not need a good earth to operate safely so if there was faulty earth you would still be safe. I understand the differences in the systems you elegantly described, however, so called electricians on the site did not answer my question which was:- If there is no earth present at say an appliance and a fault occurred how would the RCD detect an imbalance if there was no path to an earth. I assumed the path would soon become a apparent when a person touched the the appliance then the RCD would trip on contact if other things were in place of course. However, from experienced this 30ma used to trip it gives quite a jolt and from other sources I understand can result in problems for people with heart defects. What is your take on this?
+John W The imbalance occurs when someone or some other earthed object contacts a live part, current then flows through the person/object into the ground. This does mean the person may feel a shock, but the RCD will limit the shock to a very short duration.
Although a 30mA RCD will trip at that level, it does not limit the current in any way, so it is entirely possible for the current to exceed that significantly, which may cause problems for some people. However disconnecting the supply quickly (less than 200ms for a typical RCD) dramatically reduces the possibility of injury or death.
Having an RCD is still far better than not having one, particularly with the prevalence of double insulated appliances which do not have any earth connection.
Thanks John I have been aware that 200ms exposure at 230v can cause heart fibrillation and affect pace makers in vulnerable people. I would never dream of using a system without a combination of the two and was startled by Electricians even suggesting RCDs could be regarded as safe without an Earth presence.
Very useful, thanks. But does the polarity matter - the hager and the British General (CUR63330A) are opposite ways round?
Depends on the manufacturer, some can be connected either way, others not.
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.
Thanks, very informative. I've looked at my fuse box and noticed the bathroom wall fans are not on RCD, only my kitchen appliances are on RCD. That was very irresponsible of the electrician. I then checked the RCD test button and it does nothing. Time to call the electrician. The MCB/RCD combined switch you showed is a great solution for the bathroom fans, didn't know they existed.
As a point of interest. If you test on live wire that is on RCD using a neon screw driver, such as in your other video, should that not trip the RCD switch since the human body will earth some of the current and hence will not return to the RCD unit thus causing an imbalance in current between the line and neutral?
A very good question.
A majority of RCDs have a fault current rating of 30mA. Now 30mA passing through your body is described in 17th Edition Wiring Regulations as "10-15mA: Muscular contraction, can't let go. 20-30mA: Impaired breathing". Etc etc.
Now using Ohms law, from John's video, the resistor was measured at 1.535Megaohms (1535000ohms) and John was using 250VAC (or there about), so the simple maths is I=VR (250V / 1535000Ohms = 0.0001628A) or 0.16mA.
0.16mA is 'barely perceptible, no harmful effects' so an RCD would not trip in this instance, you'd need another 29.84mA for the RCD to trip.
-Andrew
copelandaa Thanks for that explanation and calculation. I forgot about the tolerance before it trips.
But are you saying that the built in tolerance level is actually lethal if it doesn't trip?
chinacane 30mA can certainly kill someone, it depends on the exact circumstances. - and if someone contacts a live wire, the current can easily be more than 30mA even with the RCD - the current is determined by the impedance of the fault.
The RCD only limits the duration of the shock, not the current.
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.?
How much would you estimate the cost to change an old Wylex for shower to RCD parts and Labour any idea ?
You helped me today John. Thanks.
Great explanation! Thank you!
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?
will electricity boxes in houses (in the UK) have RCDs in them or is it just circuit breakers.
+Marius Ammann Newer installations (under 10 years) will have RCDs as they are required on virtually all circuits. Previously (10-25 years) RCDs were required for socket outlets only, and before that they were typically not used at all.
Hi Jon . How does RCD testing using a tester work, a tester for example inputs 2x and 5x voltage. ie how does it create the imbalance to earth? Thanks for the videos.
A tester simply has a resistor between the line and the protective earth. This creates the fault. This also means that a tester will not work if there is no protective earth. The test button on the other hand creates the connection between line and neutral bypassing the RCD so it does not need earth.
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.
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
What is the switching mechanism used ??
Please can you clear up the loose cable argument you read about. I can’t see how a loose line or neutral can cause a trip surely total current flow will be balanced all be it unstable etc. Thank you for all you give to us in terms of education.
Thanks for the video, one question, it does matter how you wire the RCDs, the flow between blue and brown (life and zero) need to be opposite on the RCD. You cant just put the outside life and zero on the top contacts on the RCD, if I understand this correct.
Some RCDs can be wired either way, others not. Check the manufacturer's information.
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
my question to Mr Ward...
does the earth connection can compensate for RCDs or vice versa???
what happens if both are existing in a appliance (e. g. geyser)?
which one of them is the most important?
thanks in advance....
The earth is most important. An RCD is for additional protection, not an excuse for a missing earth.
I never really looked at an RCD before. I always assumed that they would work when they detect any current going through the earth but i suppose that would be dangerous if the earth was missing or had a faulty connection. So would i be relatively safe if i started to receive a shock from a mains socket that contains no earth? The RCD would see that some current is being used but not returning and thus trip my mains? I have been worried about many of my sockets not being earthed as it is a French house from the 70's. But since i have an RCD i should be safe anyway?
What sized resistor should i use to test my RCD? If i touch a resistor from live to the floor of my house at some point that should trip the RCD 100Kohm?
RCDs don’t trip soon enough or with low enough current to protect you in all circumstances. 30 mA RCDs come pretty close, but electricity behind it can still, kill you if you’re really unlucky.
It is helpful video, thank you very much
but I want to ask you some question:
1- how the current amount will be the same on neutral line back of load as phase line, in another words how the consumption of power will be on voltage or current amount ???
2- how the transformer will be in one end 0V and the other end of transformer not effected and stay 230v when you connet the 0v end to the ground, although the two ends in the same wire???
I will be glad if you answer me
A transformer isnt just a wire with two ends.Its a coil and because of that there is a magnetic field.A magnetic field has always a zero and a live side.Even in Direct Current(DC)I hope i enlightened you with my poor English.
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.
Hi John, Great video. I am installing an electric shower in an upstairs bathroom and the consumer unit is downstairs. I have purchased a stand alone RCD which I want to install directly above the consumer unit as the shower cable goes up to the bathroom. Being A.C. does it mater which way round the power goes into the RCD ?. Obviously for simplicity I would like the power to go into the bottom of the RCD out of the top. Many Thanks...
+ws74rq111 It doesn't usually matter. Most have a diagram on the side to show the wiring arrangement.
+John Ward . Thanks for the speedy reply so late at night. The only difference I can see is that the internal circuitry of the RCD is powered down when tripped as they would now be on the "cold" side of the internal switch. Goodnight and thanks again.. Regards. Paul,
Thanks for sharing RCD, now i really know what it does.
Hi John, want to understand what happened.... I switch the CB off for one circuit of a wall socket , other in use, and replacing the socket as it was broken, I think by mistake the N touched with the Ground, nothing happened, just the RCB went off . Is that because the returning current from other circuits ( all N are connected together in the panel ? ) found a shorter way to earth and caused an imbalance? Again No live on that circuit. Thanks
Yes, the neutral is still connected and due to current flowing in other circuits the neutral will have a slightly different voltage to that of the earth. Connecting the two together causes a small current to flow via earth instead of neutral, and the RCD detects this imbalance and trips.
Thank you for the reply.
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.
You talked about imbalance tripping the RCB.
So, with a 3 phase RCB trip if there are different loads on different phases (load imbalance), will it trip the RCB?
Or, the zero sum rule is the real key and the RCB will trip ONLY when some current is leaked out to earth.
A 3 phase RCD has 4 connections, all 3 phases and neutral, so different loads on each phase still sum to zero.
hi john. In my power box the active wire from my main switch- goes into the breaker- then the rcd- then into the house, rather than what seems standard; wire from main switch- rcd- breaker - then into house ..... is this ok? and I'm thinking if I put in another rcd for other breakers I will copy the existing rcd setup.. what do you think?
Doesn't matter, most consumer units are configured with the RCD first, but it will still work exactly the same the other way.
Or use RCBOs which are the breaker and RCD combined into a single device.
@@jwflame thankyou- its hard to find this information on the internet.
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.
CUR6330 technical specifications:" rated residual current making and breaking capacity I(delta)m 630 A.
What does it mean :"making and breaking"?
Making is when it is switched on, breaking when it switches off. If a load is connected there will be a high current pulse when switched on particularly with things like motors. If a fault occurs there will be a very large current flow for a short period. The contacts must be capable of connecting/disconnecting without being damaged by these current pulses.
Excellent. Masterclass.
Thanks for the RCD information. I live in a remote area with no mains supply. I have a solar panel set up with a converter giving 5 Kw max at 230 V. I installed the system myself and put in rings protected with 2 pole "trip" switches. The main input from the inverter passes through a Hager "Residual current device - int diferential". I assumed that this would protect people who touched a live wire and the circuit in case of a short. Neither of my cables is connected to earth hence both sides of the system are "live". Your video tells me that i got it wrong. What should I do? or where can I find the required information? I will be grateful for any help you can give.
Mac Mudie The RCD won't work, as there is no reference to ground. However this also means people would not generally get a shock from touching a live wire, unless a fault to ground has already occurred within the installation.
There are various methods of protecting such installations, further info here: xo4.uk/x/ect178.pdf (PDF document).
Good video thank you I just got a 1500w inverter and was thinking of buying a plug in RCD for more safty. But now i see there is no point as it wont work thank you. saved me some money lol. Plus intresting video.
Videos are very good, but I'm dying to know what's the formula that dictates when and where In the video those copyright notices appear. They seem to just appear at random for 5 seconds for no discernable reason
There is no formula, it's entirely random.
@@jwflame ahhh, making it maximally painful to edit out? Or some other reason? I like it, it adds charm
Ok, the scenario with the Generator with having no fault current to earth doesn't result in an electric shock, but the 1 thing I really want to know is with wall power, if you touch just the active and you are standing on concrete floor with rubber boots on, will there still be a current path to earth? Also the rest of body is isolated so your not touching neutral or an appliance etc.
In theory no shock - but in reality it's more complex. All depends on how effective those insulated boots actually are, which will also depend on moisture, humidity and so on. There is also capacitance to consider, as an insulating layer between a live part and earth forms a capacitor, and the other possibilities of someone in that situation accidently being in contact with something else.
@@jwflame Interesting... thanks for info. It's just because at work there have been a couple electric shocks, mine was I actually had twisted a live conductor with no shock and it wasn't until I earthed myself I got a boot.
The next 1 was a worker stripped a door heater back and it was live, 1 finger was on the metal of pliers and he instantly got a boot and he was standing 1 meter away from any earth with electrical boots on. (the heater is rubber outer so it is not earthed)
I know electric shocks should never happen, but its complicated when you know the circuit breaker, but somewhere along the repair the active accidentally gets put of a different circuit. Always gotta re-test...
Hi JW! Great content. I installed the RCD and now I have a question: how can I test and be sure that it actually works? When something bad happens with the washing machine in the bathroom how can I be sure that the RCD will switch off? Thanks!
There is the button for testing.
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!
excellent explanation, I have a question on another topic, I hope you can help me, I have a pool pump that works with 2 wires 220V, 110V per wire, (without neutral), would you recommend me to put a differential circuit breaker? If your answer is affirmative, how would it be, since the circuit breakers bring phase and neutral, I would need a 3-wire circuit breaker (2 phases and 1 neutral) where I connect the output neutral, if the pump only requires 2 phases (110V), , waiting for your attentions, thanks a lot
2 pole, 220V breaker, with just the 2 phases connected. Neutral not required.
MCB or RCBO or RCD TYPE ? THANKS
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.
if a neutral wire touches earth wire and then trips .is that good or bad ?
Very good clear information.