What is foundation earthing? - A new requirement in BS7671 Amendment 2 (draft for public comment)

[@efixx]

Does this change mean electricians will need to be onsite before the foundations are even finished?

[@tresslerj1985]

Historically yeah.

[@effervescence5664]

Yes. As in some cases in the past few years where new build estates have been constructed on "former" flood plain land, after six months they've raised the base floor level over the original foundation and not extended the foundation electrode. I find more are opting for SEREE which can be laid last before final driveways are completed but after the majority of the new construction.

[@Marcel_Germann]

In Germany these electrodes are mandatory since 1980 for new construction. The earth electrode is installed by the construction company, their responsibility, they also have to test it. The electrician tests it again when he performs his work, like you would do it on an EICR. The borders between the different crafts are fluent here. That means the plumbers know that they have to bond water- and gas pipes to the equipotential bus bar of the house and which size they'll have to use. Also the phone guys and the cable TV guys know and do that. The shielding of the antenna cable must be bonded to the equipotential bus bar. And back in the old days the plumbers here bonded metal tubs and shower trays.... And sometimes a soil embedded ring electrode must be installed, for example if the ground water level is too high in the area so the foundation must be a water proof tanking. In that case an electrode embedded into the concrete wouldn't work. In retrofits only this is the best solution, a simple earth rod is better than nothing, but the best (and most expensive) solution is the ring electrode arround the building.

[@evzenhedvabny6259]

Yes it does. As they do in Germany, or Czech Republic.

[@Marcel_Germann]

@@evzenhedvabny6259 You can only test it when the job is done, the concrete is poured and cured. And in most cases these companies have educated guys there which are no full educated electricians, but they can perform the measurements which are required for that job.

[@noskills9577]

I’ve had a play with this (ish) this week whilst putting a rod in. Did a Ze onto the concrete embedded rebar and got a reading of just under 3 ohm - the rod was around 16 ohm. There’s great potential (no pun intended) for getting a good low earth reading from purpose designed metal work in the ground. At a guess I’d say we’ll be seeing TNS style Ze readings which is great as we’ve be designing and installing around that for decades.

[@Marcel_Germann]

According to DIN 18014 a foundation earth electrode with more than 0.5 Ohms (loop impedance) is considered as beeing defective, of course with the PEN connected. Disconnecting the PEN is not advisable, this can have unwanted problems like a floating zero were all appliances will "see" a voltage between 0 and 400V, depending on their resistance. Below 10 Ohms in the earth electrode measurement is perfectly acceptable.

[@thom78280]

In France too we prefer to use the foundation for earthing. (in France TT earthing system is used)

[@efixx]

Great input thanks 🙏

[@darkdepth1991]

Dear Joe, thank you for the amazing content. I hope you can provide us with some real construction footage of this foundation earthing.

[@antjohn5383]

Good objective site lads , I wish we had channels like this in Australia. Regards David in Peel Australia

[@JamesBilsborough]

If there is electrically insulating material surrounding the foundation, why not completely remove the concrete embedded earthing and connect the MET directly to the soil embedded ring earth electrode?

[@enriquedmu1]

It makes sense to use what is there already, but i have some questions, what does this mean for touch voltages in the event of a fault? If the building is given a potential, and we have badly installed protective devices, are we inducing more areas to get a shock off? Or am i over thinking it.

[@seanpassant3174]

Massively overthinking it or misunderstanding it. This is far safer, the UK made some very poor choices in the 60's & 70's that led us to where we are now. Most of mainland Europe doe this already and they electrical safety record is excellent, very few touch voltage issues and now broken PEN.

[@enriquedmu1]

@@seanpassant3174 probably misunderstand it. Its one of the reasons i like these videos as i want to find out more and understand it more. Cheers for the reply. 👍

[@johndufton9686]

How about talking about the use of bentonite or marconite when using earth rods in areas of poor conductivity?

[@seanpassant3174]

Even in rocky conditions in Scotland the IET / BSI test sites proved that foundation earths gave good results. The products you mentions are very different and typically used in different scenarios and applications. Marconite can be very expensive and doesn;t always deliver value ££ for lb.

[@RWATraineeElectrician]

So the soil embedded electrode would be installed above the dpc?

[@oldbutstillcurious3615]

No, not if I am correct. The metallic electrode material must be in contact with ground, either directly - or through the concrete 'floor' which is poured over and the rebar 'mesh'. The base of the concrete slab will be in contact with damp earth.

[@seanpassant3174]

It's about time. The UK made huge mistakes back in the 60's & 70's by not adopting this method, it's safer & more reliable. My company have been involved in helping the IET / BSI test sites and the results achieved using steel (cheaper than the usual UK copper) have been excellent. As we move towards "prosumers" generating and potentially storing energy in our homes this will provide a safe, reliable local earthing system spreading fault currents over wider areas than just an electrode reducing touch and step potentials.

[@efixx]

Great input Sean - look forward to hearing more.

[@Ibrahim-tv7rv]

Hi, is there a reference for calculation required for this type of earthing?

[@sumedhasenanayake4254]

Dear Sean , Thanks for the information. What is the effect on a TNS system MET is connected to a local foundation earth, can there be Surge current passing through PE conductor to the transformer star point, What is your experience. It's confusing . (In a TT sytem ,I agree that there will be no issue, however in a TN-S system ,can there by any back surge? )

[@jordylyons4648]

Very informative given there is no law for earth bonding satellite installations I think it’s great practise...

[@7600e]

Yes might get a better resistance reading than just using a single earth electrode anyway. Look up ring earth electrode as that's what you have

[@Marcel_Germann]

In Germany this is mandatory for new buildings since 1980 and the regulations are the DIN 18014 (specifications for earth electrodes), VDE 0100-540 (the VDE 0100 is the counterpart of BS 7671, and the part 540 is the part for the earthing- and bonding systems), VDE-AR-N 4100 (application guide for installation) and the technical connection conditions of the DNOs here. upload.wikimedia.org/wikipedia/commons/8/8f/Potenzialausgleichsschiene.jpg In old installations they simply used the incoming water pipe as an earth electrode. For that reason the water pipes were made of thick cast iron to prevent leakage caused by electrochemical corrosion. There's no duty to retrofit, except the city decides to change the water pipe to a modern plastic one.

[@evzenhedvabny6259]

We do it exactly the same way. Sometimes a flat steel sometimes 10mm zinc plated steel wire. Depending on designer's calculation.

[@Marcel_Germann]

@@evzenhedvabny6259 This way (round shaped and 10mm diameter or a flat steel made of stainless steel (V4A) 30mm wide and 3.5mm thick. It must be connected to the steel reinforcement of the concrete slab. So that electrode must be installed before the concrete guys come over and pour the slab. For ring shaped earth electrodes which are not covered in concrete (buried in the soil arround the house) a hot zinc dip is not permitted. They should be made of copper, stainless steel or a steel which contains more than 2% molybdenum. Blank stranded copper wire is also permitted, but only if its cross-sectional area is larger than 50mm². If the building got a transformer station built into (large apartment buildings) then bigger sizes are required, that's for standard residential buildings.

[@evzenhedvabny6259]

@@Marcel_Germann interesting. I haven't done this for couple of years so regs may have changed. As i work in maintenance now. But about 10 years ago we used zinc plated steel for everything. Stainless steel parts when steel and copper or aluminium met. Protection of steel was necessary where wire passed from ground or concrete to the air. We used heatshrink tube with glue. Some other companies used just dome kind of asphalt paint. Everything depended on our certified designer's decision and calculation.

[@zjzozn]

Nice one Rodney 👍🤓⭐️

[@scottsparky1]

It a bit like earthing the steel structure of a building. While the steel of the building is connected to the foundation. And some times you find an earthing pit with a earth rod next to every main supporting steel.

[@seanpassant3174]

That's usually for lightning protection puropses.

[@Orgakoyd]

​@@seanpassant3174 I remember hearing the term ''side flashing'' in relation to lighting strikes and steel work on ungrounded systems. Am I on the right track with this or is it unrelated? It was in this video: kzbin.info/www/bejne/o6HKcol7abqqfNk& Also does a structural steel column added in a renovation project count as a extraneous conductive part and require main equipotential bonding? I would appreciate any input you might have since you seem knowledgeable seeing your other comments!

[@seanpassant3174]

@@Orgakoyd side flash is a phenomena of lightning events, many people assume that lightning will always hit the highest point but this is not accurate. It is equally capable of strike the side of a structure, especially when the structure has a large steel frame offering a low resistance path to earth. Tall structures around the world frequently suffer damage from these side flashes.

[@ef7480]

I missed amendment 1...

[@efixx]

That was the EV bit- now mopped up in Amd 2 (you didn’t kiss much - unless you do EV installation)

[@farmerdave7965]

Please add photos.

[@nsenergysystem277]

thank you

[@Peter-yv1ws]

Looks like this will be TT installations will be replacing the DNO poor maintenance on TN-C-S systems better start practicing our exothermic welding for connecting to the rebar.

[@seanpassant3174]

It won't need to be exothermic welding. The sample sites carried out for the IET/BSI committee were clamped (actually they had torque set break off clamps that cannot be reopened ) these were deemed suitable and achieved fantastic earth readings.

[@VillainGang.]

Funny, in Europe is foundation earth used for ages, in some countries for at least 60 years and here in UK just now few days before brexit. What will be next? Finally socket in bathroom? And btw 2391 sparkies can obtain in EU after 10years on tools, here after week straight from the street 🤣🤣🤣

[@duncanstrang731]

Viliam Lang nowt wrong with a socket in the bathroom if you’ve got a bathroom bigger than 3 meters...

[@markrainford1219]

We left the EU months ago lol

[@hepontour]

Why do we need earth rods in all but name...cant the power provider give the customer earthing via supply cable. As for how other countries provide earthing...who cares ?

[@efixx]

The change is to allow for customers to operate in “island” mode. Generated own power and supply maintained if the grid fails.

[@andrewc9235]

@@efixx If the grid fails? What future are "they" expecting?

[@seanpassant3174]

Earthing specialists care because foundation earthing is safer and far superior to how the UK chose to do it in the 60's & 70's that has led us to where we are now with huge numbers of lost neutral faults and broken PEN causing touch voltages because the DNO infrastructure is falling apart and can't be relied on.

[@hepontour]

@@seanpassant3174 by huge amount of pen failures..you mean 300, in a system thats not that bad at all.

[@andrewc9235]

@@hepontour So this earth system does not use the DNO earth in any way?

[@markbradley5746]

And an example of these are shown here !!.... OR NOT..... for the literal earth just literally imagine one in your mind.... get it completely wrong then look somewhere else for a diagram or video... 🤨