Should You Install an Earth Rod?

Joe Robinson digs into the new recommendation for installing earth rods on TN-C-S earthing systems. What sparked this change in BS7671 and how will it affect electricians?
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00:00 What is Joe doing with an earth rod?
00:48 Earth electrode now recommended in BS7671
01:38 What can be used as an earth electrode?
01:50 Why the change?
02:58 TN-C-S earthing system voltages
03:33 Electrode size and resistance
03:56 Fault protection and ADS
04:25 Is foundation earthing the future?
05:20 Checkout guidance note 8
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[@andyhodchild8]

A very brave man 'putting' an earth rod so close to other services!

[@nua1234]

I always wondered why UK didn’t require earth rods. As in Ireland which also uses TN-C-S, has had earth rods on all domestic installations for decades.

[@manyshnooks]

Australia and NZ also require an earth electrode.

[@Jack-ol8bb]

they are also required in the United States

[@efixx]

I suspect it will become a stricter requirement in future editions. 🤔

[@martinbrowne4922]

Same as that.

[@huyongquan6554]

earth electrode can not help except PEN conduct fault protection device be installed inside meter box. honestly a well electrical shock proof boots and good gloves will help more

[@idrismartin9749]

The worst shock I ever had in my 55 years in the trade was on an army camp housing contract I was tasked with a 2 hour response loss of supply to a married quarter I checked the supply no voltage from live to earth and neutral I opened the grp meter box on the outside wall to inspect the meter and cut out there didn't seem to be any obvious problem there I grabbed hold of the gas pipe exiting the gas meter enclosure to pull myself up from squatting and got the shock of life I was standing on wet grass and gripping hold of the pipe. I managed to let go of the gas pipe breaking the circuit with me as the main conductor. On closer examination the pen conductor had become disconnected inside the joint in the road with the live conductor still attached every earthed appliance and bonded metal was live so if it was my property with a tncs pme supply yes I would install an earth electrode just in case.

[@huyongquan6554]

earth electrode can not help except PEN conduct fault protection device be installed inside meter box. honestly a well electrical shock proof boots and good gloves will help more

[@joanofarc708]

Where im from you have to drive down an earth rod

[@hauptuhrdotnetblog6700]

@@joanofarc708 where I’m from we drive down paved roads.

[@idrismartin9749]

@@huyongquan6554 different days back along we didn't get issued with PPE so being human if it was going to cost money it didn't get used that is how it used to be

[@charpantidiskonstantinos4790]

Here in Greece, the construction of foundation earthing is mandatory since 2010 in all new building constructions. It is controlled by urban planning and if it is not there, the building is not connected to the electricity grid.

[@JohnSmith-jk8mt]

​@johnny 71c foundation earthing is used all over the UK on large buildings normally for the lightning protection system

[@acespark1]

I thought Greece and Italy didn't bother with any rules

[@charpantidiskonstantinos4790]

Italy use TT grounding system and i don't know if they have rules. Here in Greece except the centre of Athens where they have TT grounding system, we have TN-C-S grounding system. And we had rules since always. Before 2010 we have to install 3 earth rods connected together and to the PME system. After 2010 the installation of fundamental grounding is mandatory and to connect it with PME system....

[@ashleyrowe2681]

On some recentish DNO works i found/saw that they installed a rod (although it was horizontal) when they back filled the hole. I honestly think that the supply companies should provide the earth rather then pass the buck to us installers. They know the true nature of the cables/networks they adapt to add or alter services so they should provide a reliable connection On many supplier faults i have come across over the years on their networks, when i ring to report a higher then required reading, the first thing they try to do is ask whether the system was ever an over head supply etc etc to try a get away from sorting out the failed joint etc etc If they dont want to provide a safe electrical supply service then why should all the existing maintenance charges they add to everyone bills be chargeable per month

[@gabor.nadudvari]

It can be correct as well. Rule of thumb is if you try to install like a lightning protection then 2.5 m rod or 5m horizontal conductor can be used below freezing level. (below 0.7m in my country)

[@ShaneSiKBoYBrown]

Want to buy a car? It doesn't come with seatbelts or brakes installed. It's the owners responsibility to get a qualified mechanic to fit them.

[@buttyboy100]

What you saw was another earth point on a PME system. I have noticed that whenever a joint is buried there will be an earth electrode coiled up and buried with it by the DNO, reinforcing the term 'multiple' in PME. The main earth will be an earth mat or rods at the sub-station, but if that was disconnected there would still be many other points of contact with earth. Adding one at the consumer's premises is part of a belt and braces approach. I am not sure that it should be the responsibility of the consumer to provide this.After all, in the event of a fault, you are making this facility available to your neighbours who may have made no such provision themselves. I think this should be the responsibility of the DNO....'but what about our profits...what about the poor shareholders?' I can hear them whingeing already.

[@huyongquan6554]

@@buttyboy100 if fault happened and neighbour happened touch outdoor tap or metallic pipe that will introduce step potential difference. 10meter away will produce 90% of the voltage between MET with Ture earth. I think if I know my neighbour installed electrode, I had better install more electrode if applicable, anyway I would install 100A PEN fault detection device in meter box. actually I have bought one after viewed this video. 😀

[@andrewrussack8647]

Australia predominantly uses a TN-C-S system. All LV installations have their own earth rod. A neutral-earth connection is made at every installation, referred to as the MEN (multiple earthed neutral) connection. In some states, notably South Australia due to the use of steel and concrete composite Stobie poles, a CMEN (common MEN) system is used, where the earth conductor is effectively continuous from generator step up transformer to LV installation, that is a common grounded neutral is used for all voltages. The steel joists of all Stobie poles are connected to the neutral carried by the pole, if LV is installed on that pole. In most residential areas, all poles carry a neutral/earth, bonded to the pole joists, even if no LV is present.

[@sergiofernandez3725]

I think the DNO/DSO should provide the Earth and it should be free from defect. However in all things that cost money, they are making the the Sparky and customer foot the bill. To be honest I would say that BS7671 reg 411.4.2 could be split into new build and retro fit existing instalations. It is far easier to fit/install Earth rod/spike/plate/grid during construction than it is to retro fit a rod/spike/plate/grid at a mid terrace house in your average town. To add the cat amongst the pigeons what if your house is on a looped supply?

[@seanpassant3174]

How is the sparky being made to "foot the bill"? The cost will be passed on to the end client, just like it would by the DNO. This is about which method is better, not who does it and who pays. Localised foundation earthing is far superior. The UK is decades behind most other modern countries when it comes to earthing (just see all the comments on here).

[@kuongsam2314]

how much is the leakage current of the wiring contributes to the overall leakage current.?

[@notpoliticallycorrect1303]

The actual soil at the installation will have an effect on the efficacy of any grounding system,soil types and water content etc.will alter the resistivity and effectiveness of a rod,Chalk for instance is a very good insulator. Our local church is situated on a cut out of rock,plateau on the hill. The lightning conductor is cleated across and down the face of the rock, a journey of about 150 ft to a steel post in the soil below,but some of the land round here is below the water table and soggy wet all year round.When I walk my dogs in the stream you can see across to the back of the farm buildings on the other side, and for years the old barn and all the outbuildings,milking shed etc.that were there were being protected by the earths simply being bolted to one of a huge,probably 200+ ton pile of rusting RSJs just laying in a sodden ditch behind the sheds, it looked like a proper protected joint too not just an exposed nut and bolt! I never heard of any incidents,no one being fried etc.when I mentioned it to the guy who tested my house he joked that some areas around the village were so wet you could just chuck the rod on your lawn😊

[@GripElectric]

I would say we should always check potential difference in between actual earth and a incoming neutral at multiple points if there is any potential even very minor we should go for earth rod

[@paulaustin493]

There is now so little metal work in contact with the ground on the distribution system since the late 70s early 1980s all Pvc served cables. That every bit of extra earthing is needed. It might ge worth foing done videos on the ENA guidance for earthing and what current practice is especially with regards to step and touch potential.

[@allsearpw3829]

Hi, yes back in 1983 , when building my own bungalow and installed a 32mill amp trip on a pme system on the main switch the Electrical meter fixer suggested this and sent me a letter of advise from the then SEB , Whilst having this discussion on site , I said it was about time ever circuit breaker had a 32 mill amp trip built in , HOW thoughts catch up on one , years later ,even after many years of IEE regs courses and asking lectures about this , no one had ever heard of this , when others had for though .?🤔👍

[@Hunty49]

I believed the earth electrode was to help make sure the Neutral wasn't "floating" and was 0 volts and created a separate ground path to ensure water pipes, gas pipes and appliances that used earthing. But having earth electrodes too close together with another house has been known to cause electric shock issues if there is a Neutral disconnection fault in one house, the return current will run to the 2nd house to use that Neutral path, energising any earthed items.

[@Orgakoyd]

Doesn't this happen with metal water and gas pipes already? My understanding is the lower the the impedance between the MET and true earth the better, meaning reduced touch voltages with additional earth electrodes. Is this wrong?

[@Hunty49]

@@Orgakoyd Path of least resistance. It will go back to the pole top transformer through the neutral. If the neutral open circuits, then it goes back through the earth, through the ground, and up the earth stake on the pole top transformer. Depending on how far away that is, the shortest path is into the neighbors earth stake and onto their neutral return. But also makes THEIR earth live.

[@robertburrows6612]

How many sparks test the voltage between TN earth and true earth ? . Not many . I've installed and earth rid when I get a high Ze impedance, simply because the DNO won't come out if it slightly over

[@MrBubbles.-]

What's your thoughts on regulation 542.1.1 that says earthing arrangements may be used jointly or seperately, but regulation 542.1.201 that says the MET shall be connected to earth by one of the methods. (Ive not typed the complete quote out). It's a bit contradictory that In 542.1.1 we can mix earthing systems but 542.1.201 clearly states ONE.. What's your thoughts on this?

[@andyhodchild8]

What happens when battery systems operate in island mode, if loss if supply includes loss of earth? Even with local earth rod?

[@therealdojj]

talking of earthing, we've just had our water pipe changed from lead/copper to plastic so there's an earth bond floating about but there's nowhere where we'd be able to bang on of these earth rods into the ground here so is there an easy simple fix to this or do i need to get complicated and expensive? thanks

[@andrewpeabody8587]

So why does the regulation 411.4.2 say it doesn't apply to outbuildings? I nearly added one in my garage when I laid the SWA to it in case it got damaged. Then I saw a John Ward video saying it was a waste of time as the impedance was too high to trip the rcbos.

[@ElliottHurst]

Maybe because exporting pme to outbuildings is frowned upon so they wish to discourage it and just want outbuildings to be on TT

[@chas3997]

@@ElliottHurst people get mixed up with earth fault and over load faults RCBO will operate on earth fault just before it reaches 30ma of fault current and an impedance of up to 1667 ohms. You still need an upstream over load protection on a TNCS supply before it’s TT to an out building. But if a short circuit fault occurs in the outbuilding it’s still referenced to 0.35 ohms neutral star point earth. In the event of a PME break the TT would keep touch voltages within safe limits but wouldn’t allow operation of RCBOs from over load faults.

[@banananaa]

In Finland we use a minimum of 25 meters of 16mm2 cu to be buried into the ground around the house plus the possible casting irons be grounded as well. It's not unusual to have an L-PE short circuit current over 1kA. The usual connection is tn-c-s and even tn-s requires the separate grounding

[@user-il8rm4wg4g]

In the Czech Republic, every new house is required to have a grounding strip in the foundation of the house and from this is brought out the PEN terminal, which is connected to the distribution supply from where it is TN-C, ie L1,L2,L3 and PEN. Behind the meter this is split to TN-C-S. For old houses a 15m strip and a maximum resistance of 10ohms is recommended, maximum 50m even if no resistance comes out. But in turn the LV mains distribution has each tapping point (distributor fuse box) its own earth, with a maximum of 15 ohms and 50ohms at the end of the branch. As I see the video, a similar situation was in the Czech Republic sometime in the 50's, it is a shock to me to see that this is possible in a "modern country" in 2023

[@mernokallat645]

@@user-il8rm4wg4g Czech Republic still has sockets with 2 wires, with the ground contact connected to the neutral in older houses. That was never allowed in most countries as the chance of a broken neutral is higher than an appliance with a ground fault. Especially with 2.5mm2 aluminium wiring.

[@ladams5356]

What is the correct way to install a rod? ( to avoid other services etc ) 👍

[@efixx]

Start here 👉kzbin.info/www/bejne/m4rah2qfr9Z7jdUsi=7UzfZ1qYsPYqK2aW

[@G1ZQCArtwork]

The lower the resistance (Impedance) is to true Earth the better. As long as it does not pull a fault Voltage from a nearby installation. Being a qualified Radio Amateur, multiple Earth bonding is essential on the lower frequencies, as it reduced the noise floor on receive, and encourages a better efficiency on the transmitter. Electricians would benefit from learning the Syllabus for the Radio Amateur's Exam, as it clarifies Earth resistance over Capacitance between wires in the air over the ground. Multiple Earthing increases capacitance by a huge factor. It also protects against Lightning strike damage.

[@DTech101]

Just had to do a TT on mine for a storage battery setup, I got a resistance of 2.15Ohms not too shabby but then again it is over 4.5 meters down lol

[@Flat-Five]

If this is now recommended or if it becomes required, will homeowners have to sort this out themselves or will the distributors get in touch and come and do it as I thought that would be their responsibility? I'm not an electrician, just a homeowner wondering if there's anything I need to do, thanks.

[@huyongquan6554]

For TN-C-S earthing arrangement system. we have three status: Normal status ( No fault status): the potential difference between exposed parts or extraneous parts with ground( not true earth, true earth concept is disputable, true earth potential shall be 0) vary with distance from electrode or service pipe underground. 1 meter away difference will be 60% to 10 meter away fraction factor increase to 90%, so if you stand 1 meter away from the location electrode installed, you still have 18.5*60%=11 V, it can not be 0 voltage. Earth fault status, to say fault current 400A, MET voltage to true earth to say =400A * 0.35/2=69V. 1 meter away from electrode still have 0.6*69v=42 V. for example, vehicle is 4.5 meters long, if you touch the EV or outdoor water Tap 4.5 meter away from electrode, you will have 0.8*69=56v, if you are with bare foot, that will be problem. Pen fault: MET voltage to true earth very often will be more than 210V ( normally earth electrode 200 ohm), 1 meter away from electrode still have 0.6*210v=126v. That to say, the additional electrode installation is useless for TN-C-S , except you can get electrode reading below 2 ohm, best practice is to install PEN fault detection device. outdoor metal tap is potential danger. To install good electrode, it could be cost £300 or more, depend on the condition of soil. some time you can not get good reading. To install PEN fault detection device may be same or less, parts will be £170. I will install 100A PEN fault detection device and it will future proof if you need install EV charger.

[@mernokallat645]

Interesting that its not a requirement in the UK. In Hungary at least 1 electrode is required for every building and the impedance must be under 10 Ohms even in the worst conditions like dry or frozen soil. Back in the 1960s TT systems without RCDs were in use and the grounding impedance was well under 2 Ohms.

[@user-lb8nl3dq1b]

Scary thought of having a broken PEN conductor in the road and all that fault current may be deverted down your earth electrode.

[@huyongquan6554]

how about metal outdoor tap when kids playing in garden. how about wired grass trimmer. how about outdoor hot tube with people stand on the ground can touch water inside. how about metal case outdoor lights. there are lots of potential danger situation. we talked about PEN fault with TN-C-S earthing system, but there is no regulation deal with this, except EV charger. I do hope there have mandatory requirement to install PEN fault detection device inside meter box.

[@retrozmachine1189]

The premises earthing system being pulled up to dangerous voltages in PEN faults is a problem in Australia. The system is set up here to ensure everyone inside the premises is safe but not a lot can be done for people outside of the premises where they can put themselves in contact with the premises earthing system and the physical ground (or metalic equiv of). The best passive defence is ensuring high neutral integrity. We keep the number of joints in the neutral to a minimum even to the point of not passing it through the metering. Occasionally people do get shocked, or worse, by the garden tap. PEN monitoring is under trial as part of improved network monitoring in general. There is no automatic service disconnection on PEN fault at this point, at least in the vast majority of installations.

[@alasdairmacleod5638]

What's the recommendation if you are installing a changeover switch on TN-C-S? A supply company worker told me that the generator earth should be kept separate from the distributor's earth. So when you changeover from mains to generator uou are also switching the earth. This was in vase of a broken supply neutral which could leave you with a live generator casing.

[@huyongquan6554]

yes it is. how about metal outdoor tap when kids playing in garden. how about wired grass trimmer. how about hot tube outdoor with people stand on the ground can touch water inside. there are lots of potential danger situation. Robin talked about PEN fault, there is no regulation, except EV charger.

[@alasdairmacleod5638]

@@huyongquan6554 I think there is a similar regulation for camper van pitches. They should have a separate TT system, even when supplied from a TN-C-S/TNS system

[@huyongquan6554]

@@alasdairmacleod5638 yes TT island for caravan, it suit for TT, and can easy get it. no underground service pipe. For TN-C-S property there is no chance to get good reading of electrode except you live near pond or river with risk of flooding.

[@stevesether]

I'm surprised the UK doesn't require this yet. I think we've required an earth rod in most US states for maybe 30 years now, and you have to add one if any major change is made to the system. In fact, we generally require 2 rods 6 feet apart, 8 feet long. Before that we required grounding to the incoming water pipe starting sometime in the 70s.

[@Orgakoyd]

I heard from another commenter on another video that in Greece if during the construction of a new build proper foundation earthing is not present and inspected the building will not be connected to the grid! Now that will make sure people pay attention!

[@Mike_5]

Could save a fortune in Copper (or nasty Aluminum) on the DNO supply side cabling with smaller CPC conductors if every premise had a good solid earth Rod (Known in the trade as a 'Stewart')

[@idhatemet00]

pro tip: use your roto hammer on hammer mode to drive the rod into the ground. light years faster and easier 👍

[@yuwaraaj1564]

In Malaysia the minimum earth rod resistance is 10ohms

[@jonathanrose456]

Always have

[@stevenredmond7455]

So why is this falling on the contractors rather than the suppliers? Surely they should supply the correct earthing system to all new properties.

[@huyongquan6554]

earth electrode can not help except PEN conduct fault protection device be installed inside meter box. honestly a well electrical shock proof boots and good gloves will help more. Any metal pipe such as mains water and gas pipe bonded to MET just act as electrode, as to say some how electrode has been already installed, it will still be potential danger if PEN conductor fault happen. it is hard to measure the voltage between MET to true earth, that also means you are not stand on the true earth and introduce potential. best practice to measure the leakage current using clamp meter. Why there is no compulsory requirement for install PEN/PME fault protection device inside meter box such as isloator?

[@guywhoknows]

Could you guys do a video on parallel sources on a ring main and their protection. And on garages or sub DB. There was a big thing for a few who didn't get the selective protection set up and that it can be done. And term down/up stream Re 551.7.2 This would solve a massive headache with some installations with low power sources. Or your views. Being mindful of the final circuit defined. (Source being parallel aka solar inverter) Yes a bit cryptic, but didn't want to narrow it.

[@aredditor4272]

I was taught earthing(we call grounding in the States, I know, prob a bad habit) is to provide a path to earth for lightning. We have regions in the States with crazy weather, lots of lightning. Research on it and testing of equipment is based in Colorado and Florida. Coaxing lighting into test equipment is done with small rockets attached to wire.

[@dennisfowler-dg5vf]

since the introduction of SPDs...i think having some direct connection to earth should be be done...in aTNCS system the earth is connected back into the neutral conductor...i dont know if its posibble to get a external surge on your neutral...and if so where whould that voltage go..if there is no direct path to earth

[@alerighi]

For SPD definitely you need an earth electrode. Yes, you can have a surge on the neutral, as you can with live conductors. Anyway I don't see the point of using TN these days, to what save on an earth electrode? Because you need RCDs on every circuit anyway, at least in domestic settings. Just install an earth rod and use the TT earthing system.

[@gabor.nadudvari]

@@alerighi UK is fan of TT. In other European countries TN is the standard, and it is good, because the PEN provides less than 1 ohm compared to the 200 ohm for TT, that can be supported with local rods for the case of PEN fault. Please note 3 phase supply is common in most the EU countries where the N must be on ground potential.

[@dansheppard2965]

@@gabor.nadudvari I agree. With TN and RCDs the low resistance means you've got a very reliable system to detect and clear currents flowing through extraneous conductive parts, without leaving any dangerous potentials, and without relying on vague and uncontrolled things like resistivity of soil or the building. Adding earth rods protects against PEN faults (or supply earth faults for TN-S systems). My big worry with combined systems though is that if you do get PE or PEN or even neutral failure on the distribution side, for example near the transformer or to multiple properties, if you also have an earth rod in a baically TN system you could find the supply using your piece of copper as a high-current return path, and so have a significant step potential. In that case having 200 ohms on your earth rod is probably a good thing, as someone will notice quicker if multiple supplies are using it as a return path.

[@huyongquan6554]

@@dansheppard2965 200 ohms on earth rod when PEN fault happened ( supposed normal demand is 9A) , the voltage between MET with True earth will be near whole 212V. stand 1 meter away from electrode, still will get step voltage 127V. 😵

[@huyongquan6554]

@@alerighi SPD have two type CT1 CT2 CT1 is preferred release current to earthing, CT2 is preferred release current to neutral, I do like CT2 in domestic property.

[@Baggiolyful]

Why can’t distributors start fitting pen fault isolaters ?. No more pulling main fuses when you want to do a board change and the supply is disconnected when there’s a loss of pen conductor. Oh yeh money comes before safety. Silly me.

[@joeglabus7255]

DNO bailed on earths long time ago live and neutral is what u get unless its over o.35

[@picobyte]

In the Netherlands, always! And make it properly fault current conductive! While reducing stray field near zero for any expected fault conditions. I over engineer such stuff on purpose to save me reading and memorize all those regulations.

[@gabor.nadudvari]

In my country earth rod or better like foundation earth electrodes must be installed with less than 10 ohm impedance.

[@user-il8rm4wg4g]

This applies according to EN standards throughout the EU, the 10 ohms. Unless they have a national exemption somewhere.

[@r3co0]

Ideal, more work involved when doing a charger. Anyone that installs a rod without a cat scanner is asking to lose their life.

[@Wintersky136]

1:02 no it‘s not, actually in TN-C Systems it‘s an absolute standards; BUT TN-S Systems are NOT meant to be bonded to a local earth.

[@NathainArdoin]

Why are you driving the rod? BUY THE Cordless Hammer Drill with the Earth Rod Attachment... Carry On and Enjoy!

[@andrewthomas405]

This drip feeding new regs is a money earner and should not continue

[@sm1thers]

Which edition of the wiring regulations do you think we should have stopped at?

[@Mainly_Electrical]

Exactly that Andrew

[@dominicdodd9759]

".... without knowing what the author intends ... we can only spectulate ... " " ... the Regulation is very brief .. and a little vague ..." So, who is responsible for providing a good earth: Regulator - Not us! DNO - not, us either! House builder - Not a chance! Tell you what, there's this bunch of suckers we can make responsible! Sounds like a plan ... another round of drinks?

[@jurassicsparks5220]

Welcome to the realm of Australian / NZ standards