Types of Earthing System for Electricity Supplies (UK)

[@hughfowler7047]

I’m an 18th edition apprentice and 3 lecturers have tried explaining this to me. Thanks for the clearest explanation I’ve had. Finally this makes sense. Thank you John Ward.

[@fred9za]

just wanted to say thank you for providing one of the most concise and clear explanations of earthing structures

[@dumitruanton9597]

Cìâ nhta çcucu derasunaaq

[@dumitruanton9597]

On cum ma fut

[@adriantyler1820]

I only have experience where I can say for certain. 1. Only phase and neutral conductors are supplied. 2. No earth rods are installed at the transformers. 3. No earth rods or bonding to re-bar in the concrete is carried out. 4. Therefor this is a substandard TT system. 5. Sometimes earth and neutral are joined together making things worse. Go watch my Facebook video Samui English Electrician

[@robinmyman]

As they say...a drunk could understand that John...couldn’t be clearer...excellent. Thanks.

[@mk9367]

What can I say John, except you have an excellent way of passing on the concepts in a simple and concise way. Call me a sado but I so much look forward to your articles.....

[@paulkurilecz4209]

Fascinating overview of how the UK system approaches electrical safety. I am in the US and I can now see the advantages to our system of having a center tapped neutral on the distribution transformer secondary. The earth (grounding) conductor is connected to the neutral at the entrance to the structure and there is an earthing rod driven at the structure.

[@leon4911lt]

What a legend. I'm doing my level2 electrical installation and types of earthing arrangements is part of the installation methods unit. the diagrams used by the college were usless so thanks for this...

[@ElectricBowman]

This is a fantastically straightforward and clear explanation of earthing. Thanks a lot, JW

[@gavintillman1884]

Clearest presentation I’ve seen on this topic.

[@petergambling671]

Thank you so much I'm doing my 2391 and I'm dyslexic so need as much help as possible and your teaching is amazing for me very clear and to the point thanks again 👍

[@tonyburgum]

Probably the best explanation I have seen. Thank you.

[@Marcel_Germann]

In Germany you could find TN-C (older buildings) or TN-C-S (modern buildings) are the most common systems. But sometimes you could find TT, which depends on your supplier. The buildings with TN are fitted with an additional earthing rod for the cable failure you described at 10:48 min. Formerly they used the incoming water pipe, but now the most water pipes are made of plastic and the earthing rod is placed in the ground plate of the house (newer ones) or got a separate rod. And the most building connections are three-phase-current. The three lives L1, L2 and L3 all have 230V measured against N (or PE), but 400V against each other, so you've got two voltages in your system.

[@okaro6595]

In Finland TN-C was also common earlier but after 1989 it was allowed only with a 10 square mm PEN-wire.

[@Marcel_Germann]

@@okaro6595 Same thing here, PEN only permitted if it's at least 10mm² copper or 16mm² aluminium.

[@darkbyte2005]

Thanks for explaining the types of Earthing systems , Everyday is a electrical learning day!

[@sjokomelk]

Here in Norway the customer must provide an earth rod regardless of what system is being used. Even TN-C-S-systems must be connected to earth where the PEN is split to N and earth. So whatever happens to the earthing from the power company, there will be a local, good earth point.

[@jwflame]

sjokomelk That is also permitted in the UK - however it is not required, so is almost never done in reality.

[@RobertSzasz]

***** in a T-T system can you bond the earth and neutral at the premises demarcation?

[@jwflame]

Robert Szasz No, only the electricity supplier is permitted to do such things. Therefore you are stuck with whatever earthing system they provide, or ignore theirs and use an earth rod / TT system.

[@ElliottVeares]

***** Although sometimes you can call the DNO out for them to convert a TT system into a TN-C-S one, albeit at a cost.

[@Eeroke]

+sjokomelk Same in Finland, I think we are almost 100% TN-CS. If you have IT-system, wont that mean that an Edison-screw light socket has its threads live too? Or do you use bayonette mounts?

[@caaaarter]

Your videos are so thorough and articulate the subject very well.

[@thabood]

Hi John, your videos are fantastic. I am currently doing a 2 1/2 week course in domestic installations - my instructor no doubt knows his stuff but dear god he does not know how to teach or communicate. I have highlighted the most important things for me to learn this weekend and you have addressed two of them in the last half an hour. Thanks!! :) *subscribed*

[@johnschroeder3072]

In Australia we have a MEN (multiple earthed neutral) system where the star point of the transformer is earthed and each house is supplied with active(s) and a neutral. At the main switchboard an earth stake is connected to the main earth terminal and a link is main to the neutral terminal. This means that any A-E faults will flow through the houses earth wires then go back on the neutral. If there is a fault with the neutral as well and it is broken then the current will flow through the earth stake to the transformer, providing the best of bot options 1 and 3 from the video.

[@petercrane8216]

The best system

[@Marcel_Germann]

That's the TN-C-S system. In Germany is this the most common system too. But only in houses build or modernized after 1973. Before this date TN-C was the common system, with no separate wire for N and PE. You've got only one wire for this, the PEN.

[@johnschroeder3072]

There are some pen systems in Australia but it's not very common and only in particular circumstances

[@Marcel_Germann]

Now the PEN is in Germany allowed only if it is minimum 10mm² copper or 16mm² aluminum. But only for new installations, the old ones made before 1973 succumb to the right of continuance. But only if they are not unsafe, making massive changes (extensions for example) and if they no longer conform with the regulations that were valid during the time of installation. A change of a wall socket, lamp or a switch does not affect the right of continuance.

[@brianlopez8855]

I knew JW was the place to come for this information. Looks to me that in the 'absence' of an earth, the neutral simply needs to be connected to the earthing cable inside the house at the board.

[@DPH667]

these videos are so helpful. I've nearly completed my City & Guilds Level 3 Electrical Installation Diploma and this content is really helping with my wider understanding and prep for exams. I like your style of explanation, thank you.

[@randacnam7321]

TN-C-S is also the standard for system grounding in the US and Canada and has been for quite some years, except it is common for the main distribution board to have its own ground rod connected to the ground bussbar. The only other difference is that the supply transformer has a 240V center tapped secondary which is grounded and the end taps providing the 2 120V hots.

[@johnburns4017]

I think termed as single phase 2 hot wires?

[@NathanielStauber]

@@johnburns4017 It's more commonly called split phase.

[@NGaugeVideo]

Just wanted to say a huge thanx to you. Very concise and descriptive and made what seems to be (sometimes) difficult to understand, understandable. Great speech and great use of visual aids. Thanx again😁👍

[@PerMejdal]

In Denmark the TT system is exclusively used. RCD are required on all installations which supply up to 20A, including old ones that was made before the invention of the RCD. It is the consumers responsibility to make sure a device has ground a connection, and it is only mandatory make the ground connection on domestic appliances.

[@danw1374]

I live in the UK. Our earthing system is TT. Our house was built in the late 1960s.

[@mikemercury3656]

A clear presentation style going straight to the key points- a very refreshing change from some of the other vids I have seen! A thumbs up from me!

[@MRubio1978]

Thank you Mr. Ward even though i reside in the states your vlogs help me immensely.

[@fussydk]

Great video! Here in Denmark we pretty much only use the TT system. I'm not sure why... but i guess it's because the electric company like the idea that they won't have to be responsable of the PE connection.

[@PubliusScipioCornelius]

Here in Italy we also use TT for houseolds, only industrial use TN, I thik that's because earthing, in that case, is on the customer so if earth conductor fails, the power company has no responsability.

[@bawzworkz5574]

How on earth (no pun intended) can you get proper Earth conduction in Italy with a TT system, especially when for example you live in a rocky terrain? You guys have to drill 30M deep rods or something? :P

[@tcpnetworks]

MEN is the standard here in Australia. It's a TN-CS system, with a separated neutral/earth bar arrangement, and a earth rod in the ground. We have to find resistance as low as we can get - typically 1-10 ohms. Some sites (Centre of the country - sandy country) can see earthing rods 10-15M in depth. We equipotentially bond everything to stop balance issues.

[@JC-zi8qc]

Excellent video, for the first time really understand the three different earthing systems. Please keep up the good work!

[@fardellp]

We have been "PME'd" here but my neighbour (same phase) is TT. My neighbour's system tripped (the voltage type you mentioned)but her fault also tripped an RCD in our property. Looking at you diagram, i think i can see how this has happened. Thanks you for such a clear explanation.

[@davidramsay6142]

Another great video. Comprehensive, clear and concise.

[@alanbrady4318]

I commend you on the simple and clear demonstration of the variable systems. Well done.

[@Tammas]

As an ex cable jointer I actually have had a shock from the N/E conductor of a 1ph concentric service cable! The shift electrician had attended a property and said there was no incoming supply. Labour team had been told to open an excavation over the service so I could cut and test. As soon as I removed the PVC sheath, I got a rattle. The cable had been damaged nearer the service joint and strands cut, water got in and the cable blew open circuit to the joint and phase to N/E towards the house! We weren’t issued with the much hated neon testers in those days. 😊

[@Tammas]

Should have said the phase wasn’t open circuit, just the ne.

[@metersocket00]

Great explanation!! In the USA we have 2 hot wires 120/240 and 1 ground/neutral the grounds and neutrals are bonded inside the main panel. The nec requires 2 ground rods for each electrical panel inside the house.

[@williamshilling1862]

It's 2 rods if you have more than 25 ohms only with 1 rod. Wrong on each panel board. I for the main, none for others as they are sub's using se-r. Unless it's an outbuilding. Still uses the se-r, but also requires the rod.

[@Faddnn]

In main land Europe it is more common with 3 phases + neutral configured in a star system. 400V between phases and 230 between phase and neutral.

[@shriramvenu]

A Malaysia we follow UK specs most of the time (down to voltage and socket type), though most households here use TT earthing. TN systems are virtually unheard of.

[@stikndip]

Very good. Here in Australia we use the TN-CS system but the main earthing point is connected to an earthing electrode via the main earthing conductor and to the main neutral bar on the consumer side via a link which must be the same CSA as the incoming neutral. We call this the MEN link, and the system the MEN system (Multiple Earthed Neutral) as the neutral is earthed via the MEN link and in various points back to the TX star point. The consumer main neutral therefore functions as a PEN conductor. As JW mentioned, we do occasionally get instances of open or high impedance consumer main neutrals and shocks have occurred. RCDs clearly won't open as there's no current imbalance between A and N on the consumer side. There are also hazards if consumer mains are connected with incorrect polarity but RCDs (if installed!) will open if current flows to earth in these cases. Things are easier when you have only the one system! :o)

[@thatcolinbloke]

Currently studying 17th edition and the earthing had me baffled but your video has cleared that up, great vid thanks

[@obviouslytwo4u]

did you make it?

[@MarvylousTV]

when he said hello I'm JW.. you most certainly are John Wick with this... You my friend deserves a seat at the High Table. 👏👏👏👏

[@BensSightSoundandAuto]

In Australia, the Multiple Earthed Neutral (MEN) earthing system is used and is described in Section 5 of AS 3000. For an LV customer, it is a TN-C system from the transformer in the street to the premises, (the neutral is earthed multiple times along this segment), and a TN-S system inside the installation, from the Main Switchboard downwards. Looked at as a whole, it is a TN-C-S system. So, normally there will be a link in between the neutral and earth bus bars behind the switchboard, as well as at the local transformer.

[@Tensquaremetreworkshop]

Had a case where a screw shorted light switch switched line to earth. No RCD. Only symptom was the combi boiler kept tripping out on flame failure. Only when the Utility room light was on (not obvious at the time...) On inspection the live was 140v above ground at the boiler- flame failure detector required more! The earth spike was underneath patio paving, and may have been quite dry... On bright days there was no fault to find!

[@alimoussaali3318]

Thank you. I've been searching answers about this for long time and now got them from you. I enjoyed your video.

[@johnbonthron8528]

John, many thanks again for an very clear exposition. Well done.

[@fardellp]

Re supplying outside marquees etc from a TNC-S system - the danger would only arise if that supply came from BEFORE the "C-S2 split. Provided the supply to the marquee etc. is from AFTER the C-S split all would be fine- just like stuff in your house.

[@OldLordSpeedy]

Here in Germany we use TN-Net, TT-Net and IT-Net. The TN is splittet into TN-S, TN-C and TN-S-C. We use normal 3 L Phase, some old houses have only one L Phase. The power cable come in house direct into a big fuse for every phase - at this point the 'Saved Earth' and 'Neutral' go to two difference lines. This place is the exchange point between the power company and my home power net. After this I must install the Watt-Meter from my power company. After this we can install every RCD how we want use ... Most older installation haven't one. For Thailand I not know the situation, we use there an own transformator ...

[@winner1338]

Is it allowed to make TN-S-C ?

[@rishaalramdeen2112]

The explanation at the beginning, about the transformer grounding cleared up so many questions for me, thank you

[@PhilReynoldsLondonGeek]

There is a label on the cutout here that says "This installation is connected to a PME system" - so that confirms mine. A house we lived in before had a plate on the cutout saying "PME system" too. However, we also lived in one house where the supply came in from the poles, and that was TT. Our ELCB was a Chilton voltage-operated one.

[@Yes-ng6rf]

Here in the land of convicts and sea front properties the neutral wire often corrodes off in the outside connection box, we almost exclusively use M.E.N same as your TT supply but each customer has a removable link between the neutral and earth in the consumer unit for testing, this provides a limited path to the transformer when the incomming neutral fails.

[@christopherlowrie9484]

SSE are now installing more and more TN-S systems on new connections work. TN-S is now always used when connecting up metal clad buildings or connecting to the old PILC cables. Funny how everything seams to go full circle. As a cable jointer I personally think that TN-S is a better system. Really good vid by the way.

[@michaelcostello6991]

These videos are great. Very hard to get this information presented in an understandable manner

[@nigelconnor2460]

great video, very clearly and well explained. However 2 points. Most of Northern Ireland (rural areas) are still in TT. My house built in 2006 was done in TT. Also when you say neutral is the same potential as earth. Must be remembered that in an AC system half the voltage is carried in the neutral and the lifter you get when you accidentally touch between neutral and earth is worse than live to neutral (or at least always feels much worse!) Overall, well done.

[@adamr9600]

Thank you.. your videos are helping me massively with retraining as a sparky. I really appreciate you doing this for others to learn from :)

[@robertlee4878]

Thanks John , This is exciting ,I am starting to understand , may be its the white board but youve just broke a barrier . Before i know it I'll be wiring a plug !! Seriously, the other experts who try to explain should come down to our level and see what its like , its no fun down here ,but you obviously know a few thickos and kow whats required

[@jimanonymous113]

We use TN-CS in the US but we additionally attach a bare wire from a ground rod at the electric meter to the earth terminal in the fuse box. We also run a bare copper from the rod to the nearest hose bibb, I think for discharging lightning. The plumbing would provide a path thru to the utility's piping system which used to be metal. It's probably changed since plastic supply pipes were introduced. Wait, many pipes from the 60's were asbestos-cement which i wouldn't think was conductive so I'm not sure of the system. They may have terminated with a ground rod at the water meter in that case.

[@petergertic7736]

There is another type of Earthing that you could of included. It is called PNB. Normally used for one domestic supply only to a single phase 11kv - 230 transformer where the earth for the transformer is via the neutral block on a 100 amp cut out connected by a 32mm covered copper wire to earth electrode/pin in the ground. Although historic, lots still exist and are in use in Dorset/Wiltshire/Hampshire and Somerset.

[@tubegor]

The electrical supply is explained wonderfully. My thought is: if we do without grounding, the power supply will be similar to safety Tafo. Wouldn't that be much safer? Unless someone touches the L and N lines directly. Grounding causes more problems is my opinion.🤔

[@jwflame]

It's safer but only until some fault to Earth occurs somewhere - it's then an uncontrolled earth referenced system. Isolated supplies have their uses, but only in strictly controlled and monitored environments.

[@tubegor]

@@jwflame You are extremely competent and know what you are talking about. What has become so rare today. Thanks!

[@James_Bowie]

At 10:46 in that instance, where you show the break, the appliance would cease to operate as there is no return path (neither N nor E). The more dangerous situation is where the Neutral circuit is broken downstream (towards the transformer) of the closest earth rod, in which case appliances will continue to operate using the E path as return, thereby putting metal appliance and metal pipe surfaces at, or near, line potential.

[@michaeltb1358]

One point you didn't mention. If you are far enough away from the transformer, the voltage drop on the lines can be significant. Where I used to live voltage available sometimes dropped below 200v. That meant the Neutral was no longer zero, and could be anything up to 20 volts above earth. Even in my last house there was enough voltage on the Neutral to trip the RCD.

[@aliasgharkhoyee9501]

How does neutral gain 20v? (versus dropping)

[@johnkeepin7527]

Quite a few years on! Well presented, but it would be useful to observe that it's usual to require cross bonding between Earth and copper piping within houses - e.g in my place (which has TN-C-S) the water and gas pipes are cross bonded, with the underground pipes being plastic, so that all the exposed copper etc is connected to Earth. Plumbing alterations should take account of this, if there are any electrical disconnections in the installation.

[@TheEulerID]

That is an important subject, and John deals with it in a separate video on bonding. However, bonding is not earthing; bonding is to avoid a voltage potential between metallic parts in a building. It's related of course in that it will be bonded to earth in effect, but there is also equipotential bonding.

[@henrybartlett1986]

Clarity at last! Many thanks.

[@roberthorsford4266]

JW, could you expand further as to the earthing of a portable generator please? I use a 1kw Honda invertor generator on board our boat, generally for battery charging only. It represents a particular problem as afloat there is no possibility of an earth connection. The boat has a 240v shore power circuit on board which is generally connected to the mains supply in the marina when in the home berth. But when away cruising I plug the generator in to the shorepower inlet socket. Other boat users have suggested that the generator to boat shorepower connection cable should connect neutral to earth, infntbkniw what the thinking is behind this suggestion. Your videos are very useful indeed - keep them coming. Many thanks, Rob

[@tfun101]

In the U.S. we drive a ground rod and attach it to the neutral point of the transformer, but it looks like you guys attach the ground rod to one of the ends of the transformer. We also have corner grounded Delta systems here too. Soooo I guess you can ground a transformer anywhere in the coil you want to and it will still have the same benefit for lightning, static, etc.? 😵‍💫

[@naijawindandsolar]

Thanks for your detailed explanation. Something useful for those of us in Nigeria

[@w0ffe]

In France, TT is the default system for everything; in new construction they typically use a earthing "ring" with wires buried all around the concrete foundation instead of rods; RCDs are mandatory. Here in Canada IT is used in Healthcare facilities; these systems are subject to very strict rules.

[@robinheijblom2929]

+w0ffe I think IT is only used in Operation Rooms. Most non OR's are usually TN-S.

[@nigelspender4931]

Just found your channel. Many thanks for these videos. Extremely helpful.

[@kevsbear]

Hi JW very interesting I’m on the PME system For a couple of years now I’ve had the odd LED in the kitchen flicker .... but a couple of days before Christmas Day the lamp in the living room was flickering badly it’s connected along with my mother’s riser chair through a UPS and it was making funny noises so plugged the chair and lamp back into the wall socket and changed the lamp... Then on Christmas Day (2018) dinner out of the way we were watching tv when the RCD tripped switch it back on everything was fine for about 30 mins and it done it again this happed a few times through the night...( I had called my sparky and was coming out Boxing Day to have a look ) about 8am my UPS for my hard drives etc started going between battery and mains and very loud humming noises of the transformer inside the UPS Anyway sparky came out tested everything and put it down to a faulty RCD put another one in (not new) everything tested ok .... tried the old one in a test circuit and it tripped ! But as I was switching thing back on in the house came back out to speak to the electrician when I noticed a neighbour had an electrician in as well I told mines and he called him they were having the same problem as well so we called Scottish utilities they came out and was a fault underground .... I have since had the RCD that was put in go faulty again it wasn’t new plus was in when having problems ..... so new one installed so far so good But next week having a new unit installed with the new robc and a power surge on the supply into the house .... Great channel 👍

[@dcornwell7130]

I've seen a few You Tube informative videos but this beats those hands down in presentation skills, clarity, knowledge and video quality. You should branch out into "How to make a You Tube video"!

[@rayc1503]

Bless you dude, I thoroughly enjoy watching your tutorials. They're very easy to digest. 😉

[@alexmonroe613]

Outside equipment/structures/caravans etc. fed with extension leads: - (Circa 12:10 mins)Surely if the Neutral conductor got broken on the consumer side of the cutout the earth conductor would still have a path back to earth (tripping a safety device RCD's etc). Whilst long non armoured leads always present a greater hazard surely only a Neutral disconnection on the supplier side would put a metal framed object at risk (and that would apply to all earthed items in the house it's just your more likely to be in good contact with the earth outdoors?

[@martinwinfield2935]

Thanks for another very informative video. Could I ask a question on TT earthing systems. Is it allowed in the UK to connect the earth rod to the neutral at the customer end, and what would be the result or problem if this is done on a TT supply. I believe that doing this would only help by tieng the two together and thus reduce any problem of poor earth rod resistance.

[@DjResR]

To make the TN-C-S system safer we use extra ground rod connected at the point where Earth and Neutral wire is separated in Estonia.

[@callmelegend]

I love it. It's like Hugh laurie swallowed the 17th edition. You rock

[@valyardelean]

now it's doctor Ward ;)

[@KrisX7331]

In bulgaria we use shuko plugs and we rearly have separate earthing wire.In the wall socket we just put a bridge(copper wire) between earth and neutral and it works nearly all the time.

[@jwflame]

That arrangement (TN-C) is prohibited in the UK.

[@KrisX7331]

Didn't know that.Thanks for answer.

[@Mckennedie24]

I have taken discussions of these earthing system, non were clearer than this here.

[@jenko701]

If you like this topic , watch a video entitled "EW rice interviews Elihu Thomson " he's the engineer that came up with earthing " and maybe some others around the same time . Go to around 10.27 in the video and he states it was his invention for safety . I like the term you English use "Earthing " ,better than what we in the States use " Grounding " great video ps Mike Holt has good videos on this topic.

[@MrAtheHun]

Thank you very much for a brilliant explanation.

[@majorpygge-phartt2643]

Actually the old TNS cables have their lead sheath covered by a steel spiral wrap which is then covered with a fabric insulation which is coated with a tar like substance, I know as I've got one of those old cables supplying my old house, so therefore the lead sheath is not actually in direct contact with the ground so it has to rely on it's lead sheath for earth continuity. And there's loads of those old cables still in use where I live and further afield in the surrounding area. And I've also seen a modern concentric cable with separate neutral and earth conductors, the earth is formed by usually seven bare copper strands fitted around one half of the live phase insulation with again seven separately insulated copper strands fitted around the other half of the phase insulation to form the neutral with of course an overall insulating sheath on the outside. So some TNS installations with more modern cables do exist, probably where an existing service cable has failed and has had to be replaced, like the one next door to me. Old dead water supply pipes are in direct ground contact and have to be earthed at the consumer's property so they can effectively form a local earth electrode if connected, and of course the same applies to some older gas supply pipes too, like mine which is iron and that is also connected to my incoming earth conductor.

[@davidlisney2059]

A very interesting video, in my hobby (amateur radio) we tend to have grounding arrangements that attach to the shield of coaxial cable at the base of the aerial. This cable then generally connects to the equipment chassis within the house which is also connected via the standard mains lead to the standard domestic mains earth. In my set up the "ground mat" under the lawn is also bonded to the water piping of the house. It is a slight concern that in the event of a live-earth short in any part of the house a proportion of the fault current will flow through the equipment chassis to the " other ground". For various lightning protection reasons it can be very bad news to isolate the two grounding systems.. ie to provide a seperate safety earth only for the radio gear. This situation must be very widespread, presumably the answer is to make the bonding path as low resistance as feasible to minimise the current flow through the other path? We have an RCCB so presumably my question is more of a hypothetical one? Thanks for the video, most educational!

[@SMN804]

Very well explained, one query, for PME System you said that if the neutral (neutral and earth) breaks, it will be dangerous situation because no earth is available. My question is, if a neutral breaks, there will be no supply left because to complete a simple circuit we will need to have a connection of both Live and Neutral. so there will be no current flowing through and have no danger as there would be no supply. can anyone please explain?

[@davidhudson1194]

As usual always very good and clear. I wish all explanations were this good. Thank you.

[@DanJLaw]

😢

[@antonyhewlett9838]

Very clear and concise presentation, thank you

[@michaeltomlinson4977]

Just seen this excellent explanation but just one point to clarify the construction of pme type cables in a concentric manner is correct but at each and every straight joint position they are formed into one core for jointing purposes and joints fail - often the nuetral core . Up to the early 2000's the nuetral conductors on the distribution mains cable were made of aluminium and any slight nick in the outer pvc sheath of the cable results in the concentric neutrals perishing to dust again resulting in an open circuit on the nuetral conductor . The nuetrals are now made from copper for this very reason but from the late 60's onwards they were all aluminium . The protective multiple earthing element of the system should minimise this problem but in practice most of the earth spikes connected to the system serve little or no purpose as their resistance is never measured . The point being that nuetral open circuit faults on this system are not as uncommon as the gentleman suggests and damage to properties and their electrical systems are substantial especially on the 3 phase system resulting in high voltages being supplied .

[@AngloSaxonFreeBritain]

Very clear and concise information! Unfortunately you left out the IT system.

[@jwflame]

Left out because it's rarely used anywhere.

[@antoniogalluccio4213]

The earth return path within the supplier's cable of a TN-CS system is the? A. Earth conductor B. Cable sheat C. PEN conductor D. Installation earth electrode.

[@tariqmalik324]

You are clear and concise greatly appreciated

[@taddy666]

Thanks John. You are a legend!

[@johnschlesinger2009]

There is a minor error here. Most lead supply cables are covered in bitumen. The lead sheath is only visible where the termination has been made at the cutout. So the lead sheath rarely functions as an electrode. Also, in very old services the lead sheath can crack due to loading stress on the ground above, so a periodic loop impedence test is especially important on TN-S supplied installations.

[@kounoupidi]

This is what we have in Greece as well and I am under the impression that by law all buildings should also have a grounding rod that connects to the provider grounding cable.

[@apartmentswales]

Another great video, thank you JW. Just a thought here but go back to 11.17 and this time draw in the Main Bonding Conductor which as you know will be tied to the Main Earth & Neutral, this would now become the return path and act as the NEUTRAL for the Whole Building and demonstrates how dangerouse this scenario could be, making Gas and Water Pipes turn into NEUTRAL PATHS. But in Summary this scenerio you have given at least in today's industry 2020 is very unlikely to cause a problem. Trying to draw power down through an RCD/RCCB with only the LIVE Connection Connected is going to be a Non Starter as it will immediatly sense the inbalance of the Live Phase to Neutral Phase and Trip when an accessory is switched on, or will it just adopt the Earth Bonding as the Neutral and carry on supplying power !?! Mr Spence Eng

[@VAX1970]

My mains supply cable is MICS (Mineral insulated copper sheathed cable / PYRO) The earth is supplied via the copper outer, it's very old.

[@abdullahalahmadi695]

I have TN C-S properly installed is it allowed to earth the body of the motor or the control panel earthing point as add protection I can pond it to a sticking out construction steel that I conected to the building foundation which happened to be near them

[@gordonturner8544]

Crystal Clear as always many thanks

[@joshpascual7539]

Easy straightforward teaching

[@adriantyler1820]

Thank you, I passed my C&G 236 with distrinction, but never fully grasped this subject. I now live in Thailand where there is no earthing and horrific workmanship. Pretty much every building repiar I install a TT system with RCBO. Eaerth rods are ineffective ZS + 100 Ohms. Connection to buried in concrete iron re-bar works better. My forcefully implentation of these practices has been adopted by the electrical authority here.

[@bawzworkz5574]

In Belgium the TT system is common, even if we had TN-CS I would consider providing an earth loop under the property or own earthing rods. I don't trust my life to the infrastructure provided by some company, if one of my kids gets cooked while taking a bath cause some moron screwed up the cable while doing some excavation work (Very unlikely, i know) we'd be getting a Pardon letter and some financial shut up fee and that's about it. In other words as a trained sparky I would'nt forgive myself. 100Ma RCD for "dry rooms" and 10Ma for "moist rooms" is common practice here.

[@timhumphrey8245]

Hi John, I stopped the video at 2:45 'cause I was shouting at you! The mains transformer secondary winding can't be 230v one side and zero at the other since each side oscillates between 0 and 230v 50 times per second. Shorting one side to earth would strap both secondary winding terminals to zero, just before the input fuse blows... :-( Tim.

[@djc5463]

Err, no. The neutral always remains at earth potential and the relative line potential alternates about it.

[@djc5463]

Err, no. The neutral always remains at earth potential and the relative line potential alternates about it.

[@paulconnolly9414]

GREAT VIDEO....Hi john, recently visited a rural property TT supplied overhead 2 wire supply. where an electrician had found a voltage 54 v between earth and neutral. When installing a shower circuit. But could not find cause of the problem. Pulled the cu to bits and was left stumped. I myself called and isolated the installation and conducted tests at the distributor s supply only. I found a voltage of 280v to the property's electrode, which my meter could not perform a EFLI test on. Also I found a voltage of 54 volts between n+e. I put this down to distributors issue, as a visual inspection in the cables showed cables running some distance and twisted together for a section on the way back to the transformer. Opinion please john thank you

[@Tensquaremetreworkshop]

230v Wish it was. In our village it hovers in the mid 250s (Yes, often above the 253 max). Items fail. After decades of a nominal 230v the suppliers have made no moves to drop it from the old 240. A cynic would point out that for static loads it increases the power you have to pay for (by nearly 9%).

[@98dizzard]

My understanding is that despite what the sellers of voltage optimisers would have you believe the extra voltage makes very little difference on modern equipment. Most resistive loads are for heating (immersion, oven, kettle etc...) and will be stopped by the thermostat, it will heat quicker at 250v vs 230v but not use more total energy. Most other modern equipment is switched power supplies (most led lights, computers etc...) and these shouldn’t use significant extra power at 250v vs 230v. Old incandescent lamps would use more power, but they’re rare now, and some inductive loads like fans and maybe the compressor on a fridge/freezer might use some extra power too.

[@collord7249]

Hi, i have a 1900s house with a lead cable , 3 cutouts (only one in use) and a green earth cable running to a small side box( i think the whole assembly is tar filled)..my house is wired in pvc coated twin and earth...mostly grey, some white...everything works fine. my question is...there is a green earthing wire in the kitchen not attached to anything and one in the bathroom also...should i clamp them to a cold water pipe or just remove them, many thanks colin...

[@heavydiesel]

One of my customers had a farm on chalky soil, whenever they had a earth fault in the dairy it would trip the rcd in a house down the bottom of the hill!

[@robinheijblom2929]

+heavydiesel If an RCD from one installation is tripped by a fault in another installation, something is terribly wrong. RCD's should only be tripped by faults in the circuit the RCD can switch off.

[@PhilReynoldsLondonGeek]

+heavydiesel Sounds more like a VOELCB tripping because the earth rods are too close together.

[@parko1965]

Is the house fed from the dairy?

[@monkeyseemonkeydo432]

coffin dodger Yes...milk, butter, ice cream

[@linossinkala7840]

Sir thankyou you have been so helpful.i want to know rcd ,rccd and elcb to connect them on db

[@frank1847]

Brilliant and very clear instructional video. Thank you John (liked and subscribed.)

[@surajdudhe1086]

nice info about GND-earthing

[@malcolmholt8560]

in the uk the mains supply to house domestic supply is derived from a substation star transformer the center tapping is earth's so you have 230v to earth this is your the neutral .

[@elektronikmaleinfach16]

in germany we use for small stuff in most cases non polarisaded sockets! :((( it results of early systems were get 2 phases on sockets ! it have a voltage between 2 phases of 220V on a 3 phase system ! it is i think nealy everywere replaced with 400v line to line system ! but we have in older insterlations also 2 wire system everywere! only in the socket the pen is split to neutral and ground!