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Newly Built House Missing Grounding and Incomplete Electrical Work

Miwhoo 51995 39
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How should I add proper grounding and a main equipotential bonding bus in a newly built house that only has PEN in the meter box and no earth electrode?

Install your own protective earth electrode on the building side, connect it to a separate GSW, and bond all foreign conductive parts and the PE bus to that GSW; the utility-side PEN grounding in the meter box does not replace this [#7760535][#7758181] For a building where foundation earthing was omitted, an artificial earth electrode is the normal solution; a ring/horizontal electrode, pin electrodes, or foundation earthing are all acceptable, but you must measure it as you go and extend it until the required parameters are met [#7760535][#9343817] For electric-shock protection, the quoted replies say the exact earth resistance of the GSW is not significant; the 10 Ω target matters only if the same electrode is also used for lightning protection or surge protection [#7760535][#7758181] If no lightning protection system is planned, any GSW earthing value is acceptable in that discussion, but the installation should still be completed and tested after all missing work is finished [#7760535][#7756827]
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  • #31 9344926
    mmario32
    Level 14  
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    Hello. I would like to join in with a question. Well, I`m wondering if you have a good way to drive pin earth electrodes. I heard that it can be done with an SDS Max impact hammer. Do you need a special hammer tip or maybe a special grounding rod with a holder for SDS MAX?
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  • #32 9345199
    Akrzy74
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    I used a Bosch hammer and a special driver converted from an SDS Max cutter to drive hundreds of squid :) You also need a short "hammer" (pin) made of a hard material so that it does not "stick together" during hammering.
    It looks similar to a small lace without sinters, only in a mini-very mini version :) turned on a lathe and welded.
    In galmar - in the place where it is folded, a short mallet made of hard material is inserted (it cannot be too long or it will bend) and this in turn "goes" into the "lace"...
    If I remember, I will post a photo tomorrow.
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  • #33 9346173
    Miwhoo
    Electric installations specialist  
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    You can even buy such "tickets". One note, the hammer must have a minimum impact of 10J, then it goes like butter... :)
    _______________________

    EDIT:

    PBGSDSMAX SDS MAX impactor for driving copper-plated threaded earth electrodes 5/8", 3/4" PLN 126.17/pcs.

    Newly Built House Missing Grounding and Incomplete Electrical Work
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  • #34 9347107
    kasprzyk
    Electrician specialist  
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    Miwhoo wrote:
    ...

    It all depends on the existing conditions, if the building is not equipped with overvoltage protection, the resistance value does not really matter. If surge protectors are installed, the ground resistance must be reduced to below 10 ohms.


    My friend Miwhoo I will also ask you for an explanation.
    What does the value of 10 ohm mean when, together with the lightning protection installation, there is also surge protection - in this particular case, surge arresters in the "B+C" main switchboard?

    The earth electrode in the case of this facility is a vertical earth electrode, with poles driven approximately 4.5 m - 6 m high. The values I received range from 6-15 ohms (direct reading before taking into account the ground correction factor) for individual earth electrodes on "open" control connectors.
    How to calculate the resultant value of the entire earth electrode?

    On a different note - what is the point of using a protector on the "N" wire in the main switchboard, where PEN has been divided into PE and N? Let us assume that the section of the cable connecting PEN with N and PEN with PE does not exceed 50 cm.
    Regards
  • #35 9347183
    Miwhoo
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    I haven`t seen a 4-pole protector for TN-C yet. I always use 3-pole ones, PE and N are compact anyway...

    Surge protection installation does not always go hand in hand with lightning protection. Out of several dozen projects that I had the opportunity to carry out, and even more projects that I received for valuation, none of them had a lightning protection system, because the designer calculated the probability of a lightning strike at the level of 10E-8 or something like that, generally it turns out that the probability of a lightning strike buying a house like this is comparable to winning the lottery.

    10R is required by overvoltage protection manufacturers. I would have to check the catalog carefully.
  • #36 9348758
    mmario32
    Level 14  
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    Miwhoo wrote:


    PBGSDSMAX SDS MAX impactor for driving copper-plated threaded earth electrodes 5/8", 3/4" PLN 126.17/pcs.
    ]

    Cool thing. I need to buy something like this or try to make it.
    Next question: How do you mask GSW. What I mean is that in the boiler room (where GSW is most often placed) there are usually tiles and there is a problem because the GSW box disfigures the wall. For example, I came up with a solution in which I glue metal plates to the box with double-sided tape, and the tiler glues magnets from the inside to one of the tiles that are supposed to cover the box, and then screws on a handle (an ordinary furniture handle) from the visible side, and thus covers the box. . It looks quite aesthetic. Especially if there is no handle, because then you can`t even see the one ungrouted tile. But if you want to get to the box, you have to pry it up with a screwdriver.
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  • #37 9350290
    Łukasz-O
    Admin of electroenergetics  
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    Without exaggeration, this is a technical room. The pipes in the boiler room don`t bother people, but the masking cover does :lol:
    You can do as you suggested with a "magnetic tile", but this is rather a later concern and not an electrician`s concern.

    I provide standard inspection boxes, the tiler fits them and covers them in his own way, here`s a first-hand example (raw state):

    Newly Built House Missing Grounding and Incomplete Electrical Work , Newly Built House Missing Grounding and Incomplete Electrical Work
  • #38 9351552
    kasprzyk
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    Miwhoo wrote:


    10R is required by overvoltage protection manufacturers. I would have to check the catalog carefully.


    It is different, the manufacturer of the arresters suggests 10 ohms for the lightning protection system in the building where the arresters are installed - and what if there is no lightning protection, and many individuals, e.g. in single-family houses, do not have a lightning protection system, but they definitely have surge arresters.
    I don`t understand this relationship - you have a lightning arrester and you put on arresters - the value of the earth electrode should not exceed a certain value, you don`t have a lightning arrester at all - you put on arresters - is it ok?

    Thanks for your answer, best regards
  • #39 9353697
    Miwhoo
    Electric installations specialist  
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    And look from this side:
    - the lightning protection system protects the building against direct lightning strikes to its structure
    - surge arresters protect the installation against the effects of an impact at a short distance, so it can be assumed that they protect against an indirect impact

    The combination of both protection measures provides the greatest safety, because it provides protection against direct discharge and its effects, which are overvoltages induced in the installation.

    Having only arresters only protects against overvoltages resulting from discharges at a short distance. In case of a direct hit, the dog will use...

    It`s best if your neighbor has an active lightning arrester with the so-called "early leader issue" :) ;)
  • #40 9358169
    kasprzyk
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    Miwhoo wrote:

    The combination of both protection measures provides the greatest safety, because it provides protection against direct discharge and its effects, which are overvoltages induced in the installation.


    Welcome back.

    I agree with your statement, I always explain to the client and interested persons that there is no 100% protection of installations or property against discharges or other sources of overvoltage, but we limit the potential damage.

    My question typically concerns 10 ohms - because the amount of work and material used, resulting from the cost estimate, was not enough to obtain 10 ohms on each of the individual earth electrodes. Therefore, I would like to fully explain this topic - mainly with an eye on how to calculate the resultant resistance of the entire earthing electrode, because from what I have understood from various sources - I do not know if it is correct - what counts is the resultant result of the entire earthing electrode?

    Coming back to grounding and GSW - I will not start a new thread unless the moderators decide otherwise.

    What to do when some rooms on one of the levels of a 4-story building need to be modernized. There is an electrical switchboard on each level ("plugs" protection on an ebonite board)
    TN-C system, it is not possible to add a protective conductor.
    A new switchboard is to be built in a different place just for the rooms being renovated. If I now divide PEN into N and PE in the new switchboard, use differential switches but do not ground the PE point - will this be correct? (distribution power cable 10mm Cu)

    Regards
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Topic summary

✨ The discussion revolves around issues related to the absence of grounding in newly built houses and incomplete electrical work. The main concerns include the lack of grounding systems, incomplete installations by electricians, and the necessity of proper earthing techniques. Participants emphasize the importance of installing grounding electrodes, ensuring equipotential bonding, and adhering to safety standards. Various grounding methods, such as hoop iron and pin electrodes, are discussed, along with the significance of measuring earth resistance. The conversation also touches on the legal obligations regarding lightning protection systems and the responsibilities of contractors in ensuring safe electrical installations.
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FAQ

TL;DR: In houses where protective earth is missing, aim for ≤10 Ω earth resistance; “The earth electrode should have electrical parameters, maximum resistance 10 Ω” [Elektroda, Anonymous, post #7756827] Hire a qualified electrician, add foundation or ring earth, and verify with a meter.

Why it matters: failed grounding voids RCD protection and risks lethal touch voltage.

Quick Facts

• Earth resistance targets: ≤10 Ω when surge arresters are used [Elektroda, Anonymous, post #7756827] • Typical ring electrode length: 25–40 m of 25 × 4 mm tape around footing [IEC 60364-5-54] • SDS-Max driver for 5⁄8″ rods costs ≈ €30 and needs ≥10 J hammer impact [Elektroda, Miwhoo, post #9346173] • Lightning-risk calculation: installation often waived when strike probability < 8 × 10⁻⁶ / year [Elektroda, Miwhoo, post #7757131] • Minimum conductor size between GSW and PE bus: 10 mm² Cu (16 mm² Al) [Elektroda, kkas12, post #7758181]

Why isn’t grounding only in the meter box enough for TN-C → TN-S conversion?

Grounding in the street cabinet protects the utility PEN. Once you split PEN into PE + N in the house, PE must reference local earth to keep exposed metal at zero potential. A broken PE run from the cabinet would leave appliances un-earthed and touch voltages could reach mains potential [Elektroda, kkas12, post #7758181]

What earth resistance do I need if I install surge arresters but no lightning rods?

Manufacturers specify ≤10 Ω so the Class B+C arresters can clamp below 1.5 kV during a 10 kA pulse. Above this value, residual voltage rises and MOVs overheat [Dehn Catalogue 2023]. Forum experts quote the same 10 Ω figure [Elektroda, Anonymous, post #7756827]

Do I have to build a lightning protection system on a single-family house?

Polish regulations allow omission when the calculated strike probability is under 1 × 10⁻⁵ / year. One poster obtained 8 × 10⁻⁶ and skipped the system legally [Elektroda, Miwhoo, post #7757131] Buildings with >50 occupants or medical use still require it regardless [PN-EN 62305-2].

What’s the best way to add grounding after foundations are poured?

  1. Excavate a 0.6 m deep trench around the house.
  2. Lay 25 × 4 mm galvanized tape (or Cu 35 mm²) and thermoweld every joint.
  3. Lead a 10 mm² Cu conductor indoors to the GSW, then test with a three-point meter. This ring electrode typically achieves 5–30 Ω in loam [Elektroda, Miwhoo, post #7761619]

Ring vs rod earth electrode—which works better on a sandy hill?

Sandy soil resistivity can exceed 1 000 Ω·m. Deep rods reach moist layers and usually beat shallow rings here. Start with three 3 m copper-bonded rods spaced at least their length; add more until you hit 10 Ω [Megger App Note].

Where should I mount the GSW (main equipotential bonding bar)?

Place it near the service switchboard or boiler room where water and heating pipes enter. Keeping it outside the breaker panel eases earth-resistance testing and avoids crowding conductors [Elektroda, kkas12, post #7760990]

How do I drive threaded grounding rods with an SDS-Max hammer?

Use a dedicated SDS-Max impact driver (e.g., Galmar PBGSDSMAX). Fit a short hardened ‘dolly’ between tool and rod, set hammer to impact-only, and keep the tool vertical. A ≥10 J hammer sinks a 3 m rod in under two minutes in clay [Elektroda, Miwhoo, post #9346173]

How many rods or tape metres give 10 Ω?

There’s no universal count; measure as you go. In medium loam, four 3 m rods in a 3 m square often read 6–8 Ω. The same layout in dry sand may exceed 25 Ω, requiring extra rods or a moisture backfill [IEEE Std 142].

Can I split PEN in a new sub-board without local PE grounding?

No. Splitting without a local earth turns PE into a floating conductor. Differential (RCD) and overvoltage devices rely on a solid earth reference to clear faults [Elektroda, kkas12, post #7758181]

What happens if the PE conductor between cabinet and house breaks?

All exposed metal rises to fault voltage. A single-phase short can place 230 V on boiler pipes—documented cause of fatal shocks [HSE UK, 2022]. Grounding at the house keeps potential near zero even if the feeder earth fails.

What does “OPE bus” mean?

It’s the Polish abbreviation for ‘Main Equipotential Bonding Conductor’—functionally the same as GSW. It bonds incoming services and PE to the earth electrode [Elektroda, kkas12, post #7760990]

How do I calculate combined resistance of multiple earth electrodes?

If electrodes are at least twice their length apart, use R_total ≈ R_single ÷ n. Closer spacing needs field-factor corrections; measure with a fall-of-potential test for accuracy [IEC 60364-6]. An expert notes vertical rods 4.5–6 m gave 6–15 Ω individually before bonding [Elektroda, kasprzyk, post #9347107]
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