Earthing systems · Complies to IEC 61936-1 · IEC 60364-4-44
Global Earthing System (GES)
A global earthing system is created when the local earthing systems of many installations are interconnected so closely that, together, they prevent dangerous touch voltages. It is a recognised concept in IEC 61936-1 for dense urban and industrial areas.
When it applies
- City-centre and industrial-estate networks with many interconnected substations
- Campuses with continuous cable sheaths, foundation electrodes and bonded services
- Brownfield plants adding a new substation inside an existing earthed area
- Projects that must justify a compact earthing design by study
When it does not
- Remote or stand-alone substations with no interconnection to neighbours
- Sites where cable sheaths or screens are not continuous or are insulated from earth
- Any case where the interconnection cannot be measured and documented
How the system works
- Read the soilSoil resistivity decides everything. A Wenner survey at several spacings shows whether to go deep, go wide or treat the soil.
- Choose the electrodeFoundation, ring, rod, plate or grid: each suits a different footprint, soil and fault duty.
- Make joints that lastBuried joints are welded or made with tested clamps, and protected wherever metals or soils change.
- Prove it and record itResistance and continuity are measured, labelled at the pit and filed in the handover record.
Why depth beats diameter
Current leaves an electrode through shells of soil. A longer rod reaches more soil and moister layers, so resistance falls quickly with depth. Figures are for one 17.2 mm rod in uniform 100 Ω·m soil.
Design parameters
The values a consultant or contractor needs to fix before the system is drawn.
| Parameter | Typical value or rule | Reference |
|---|---|---|
| Interconnection | Low-impedance links between local earthing systems: cable sheaths, earth wires, bonding conductors | IEC 61936-1 |
| Earth potential rise | Assessed for the fault current that returns through soil after current division | IEC 61936-1 · IEEE 80 |
| Touch voltage | Shown to be within permissible limits across the area by measurement or calculation | IEC 61936-1 |
| Conductor size | From the earth-fault current and duration | IEC 60364-5-54 |
| Bonding | Every substation, building electrode and metallic service joined at earth bars | IEC 60364-5-54 |
| Verification | Earth-fault loop impedance and touch voltage tests at representative points | IEC 60364-6 |
Solution pack: component BOQ
Each line opens the LPES product category. Part codes and final quantities are confirmed on your quote from the drawings.
| Component | Role in the system | Quantity rule |
|---|---|---|
| Earthing Conductors | Interconnecting conductors between local earthing systems | Route length between earth bars + 10% |
| Earth Bars & Terminals | Main and local earth bars with disconnecting links | One per substation, building incomer and plant room |
| Bonding Clamps & Leads | Bonding of pipes, cable trays, sheaths and structural steel | One per metallic service at each entry |
From design to handover
- Map every existing earthing system, cable sheath and metallic service
- Calculate current division and earth potential rise for the governing fault
- Install or confirm the interconnections and earth bars
- Measure loop impedance and touch voltage at representative points
- Issue the study and drawings that record the system as a global earthing system
Services for this solution
Industries that use it
What the standards require
Checked against the current editions held in the LPES standards library.
- IS 3043:2026 Cl. 6.3
- Independent, 'dedicated' or unbonded 'clean' electrodes are listed as misconceptions that shall not be followed. The code recommends one interconnected, meshed earthing and bonding network.
- IS 3043:2026
- Quick estimates: a rod gives R ≈ ρ ÷ L, a strip or ring R ≈ 2ρ ÷ L and a plate R ≈ 0.8ρ ÷ perimeter, with rods at least one length apart.
- IEC 62305-3:2024 Cl. 5.4
- Type A electrodes start at least 0.5 m below ground, and 0.5 m is added to a vertical rod for the dry or frozen top layer.
- IEC 62305-3:2024 Cl. 5.4
- A ring touching soil for less than 80% of its length counts as Type A. Neighbouring electrode resistances should agree within a factor of two.
- IS 3043:2026 cl. 8.1.7
- Earth enhancing compound only where soil resistivity is above 3,000 Ω·m, never below 200 Ω·m, and in India only for lightning protection earthing, to IS 18925 (Part 7).
- IS 3043:2026
- Where soil pH is below 6 or above 10, change the backfill or encase the electrode in concrete.
Regulation and standards cross-check
What Indian regulation and the wider standards add to this solution. Paraphrased; confirm against the current official text, amendments and state notifications before relying on a clause in a tender or inspection.
| Standard | Clause | What it requires |
|---|---|---|
| IS 3043:2026 | Clause 11.1 | For industrial and commercial premises a global earthing system is recommended, and it is mandatory where a high-voltage substation stands on the premises. Low-voltage distribution is TN-S, with the source neutral earthed once. |
| IS 3043:2026 | Clause 6.3.1 | Separate or dedicated earth electrodes for individual equipment, neutrals, electronics or the lightning protection system shall not be followed. Electrodes are interconnected into one earthing system. |
| IEC 61936-1:2021 | 10.2.1 | Where high-voltage equipment is not inside a closed electrical operating area, as in industrial plants, a global earthing system should be applied. |
| IEC 61936-1:2021 | 10.2.3, Table 6 | High-voltage and low-voltage earthing are interconnected where practicable. Where low-voltage circuits leave the high-voltage earthing area, earth potential rise is held to 1,200 V for faults cleared within 5 s and 250 V beyond 5 s, unless a global earthing system exists. |
| CEA Safety Regulations 2023 | Reg 43(v) | Every building shall have protective equipotential bonding that interconnects exposed and extraneous conductive parts. |
| CEA Safety Regulations 2023 | Reg 43(vii) | Frames of generators and motors, transformer and control-gear metalwork and consuming apparatus above 250 V up to 650 V are earthed by two separate and distinct connections. Common guidance reads this as two connections to the earthing system, not two isolated electrodes in the soil. |
| IS 732:2019 · IEC 60364-4-41 | 4.2.11 | For automatic disconnection at 230 V to earth, final circuits disconnect within 0.4 s in TN systems and 0.2 s in TT systems. Distribution circuits may take up to 5 s in TN and 1 s in TT. |
| IEC 60364-6:2016 · IS 732:2019 | 6.4.3.7.3, Annex D | A measured earth-fault loop impedance is accepted when it is not more than two thirds of U0 ÷ Ia, where Ia is the current that operates the device in the required time. The margin covers conductor heating under fault. |
What we ask for before design starts
- Single-line diagram showing every source and operating mode: transformer, generator, UPS, solar
- System earthing type at each level: TN-S, TN-C-S, TT or IT
- Earth-fault current and the normal and back-up clearing times
- Soil resistivity survey with the season it was taken in
- Site layout with foundations, buried metal, fences and services
- For high voltage: current division, surface layer and whether the public has access
Engineering depth: from the LPES Knowledge Hub
Topic studies written against the current standards. Open each part for the method, the mistakes to avoid and the checklist.
IS 3043:2026 · LPES Knowledge Hub H-20
Misconceptions in earthing (Figures 23-25), the recommended meshed configuration (Figures 26, 27, 70) and zonal bonding for EMC (Annex C)
Clause 6.3 of IS 3043:2026 does something the rest of the Code rarely does explicitly: it names four specific earthing practices as misconceptions and states, in plain terms, that they "shall not be followed" (6.3.1, Figures 23 to 25) — separate or "dedicated" earth electrodes for individual pieces of plant, "clean" or "instrument" earth networks kept unbonded from the main system, and split signal/power earthing networks. Having ruled those out, Clause 6.3.2 gives the recommended alternative: a single, three-dimensional bonding network (illustrated conceptually in Figure 25B and fully in Figure 70) that ties every earth electrode, every bonding conductor and, where an LPS is present, the lightning protection system itself into one interconnected whole (Figures 26 and 27). Annex C then extends the same logic to electromagnetic compatibility (EMC): in buildings with substantial electronics, radiated and conducted interference is controlled not by isolating a "clean" earth but by the opposite — comprehensive zonal bonding at every zone boundary (Figure B-1), using the building's own structural steel, reinforcement and cable shielding as part of the bonding network. This topic is the Code's single clearest statement that safety and electromagnetic compatibility are achieved by the same design principle — one common, thoroughly interconnected earthing and bonding network — not by keeping systems apart.
How it is applied
- Applying this clause is largely a design-review discipline rather than a calculation: before any earthing layout is approved, check it against the four named misconceptions in 6.3.1 — are there separate electrodes for a transformer neutral and its body; separate electrodes for distribution boards, lifts, UPS units or electronics; an unbonded "clean" reference network; or a signal-versus-power split network — and if any of these patterns appears, it must be corrected to a single bonded network rather than accepted as a design choice, however well-intentioned the original request.
- Where the request originates from equipment suppliers or specialist installers (a recurring pattern the Code anticipates explicitly for biomedical equipment at Clause 11.2.1.6, and implicitly for UPS, lift and electronics vendors at 6.3.1.2), the correct response is not to accommodate the request but to provide that equipment with an individual bonding connection into the one common network — satisfying the vendor's reference-quality concern without recreating the isolated-electrode hazard.
- In buildings with substantial electronics, the same review extends to Annex C: confirm that shielded cabling, filter/SPD placement at zone boundaries, and bonding of every exposed and extraneous conductive part (including the neutral of any isolation transformer) into the zone's common bonding busbar have all been provided, per ISO/IEC 30129 and the relevant parts of IEC 61000.
Common mistakes
- Granting an equipment vendor's request for a "dedicated" or "isolated" earth electrode without recognising it as the exact misconception 6.3.1.1/6.3.1.2 names — this is one of the most common ways this clause is violated in practice, because the request always arrives with a plausible-sounding technical justification (interference, noise, cleanliness) rather than framed as a compliance question.
- Confusing "bonded into one network" with "physically identical wiring for signal and power" — 6.3.1.4 does not forbid separate signal and power conductors; it forbids separating them into two unbonded earthing networks. A correctly designed installation can still route signal and power cabling separately while keeping a single, common bonding network underneath both.
- Treating 6.3.1.4's qualified language ("may be found satisfactory... in small installations") as a blanket permission — the same clause immediately states the practice is a safety hazard in large installations and generally unsuitable for high-frequency EMC, so the qualification is narrow and should not be read as endorsing signal/power separation as a general design pattern.
- Assuming Annex C's EMI mitigation is only a data-centre concern — B-1 names data centres, telecommunications installations and hospitals together, and Clause 11.1.11.3 extends the same requirement to "large buildings with substantial amount of electronics" generally, not to a fixed list of building types.
- Overlooking that the recommended network (6.3.2) is explicitly three-dimensional, not the flat, two-dimensional single-grid concept a designer might otherwise default to — Figure 70's caption calls out a "three-dimensional earthing arrangement in a multifloor building," meaning floor-to-floor and structural-steel bonding, not only a ground-level ring.
Design checklist
- Before approving any earthing layout, check it against all four named misconceptions in 6.3.1: separate electrodes for one item's neutral and body; separate electrodes for distribution boards, lifts, UPS or electronics; an unbonded "clean" reference network; and a split signal/power network.
- Where a vendor or specialist installer requests a dedicated or isolated electrode, respond with an individual bonding connection into the single common network, not with a separate electrode.
- Confirm the earthing network is designed and drawn as a three-dimensional bonding network (Figure 70), not a flat, single-level grid, in any multifloor structure.
- Where an LPS is present, confirm it is shown as part of the same single network (Figure 26 for an insulated LPS, Figure 27 for an attached LPS), not as a separate system.
- In any building with substantial electronics (data centre, telecom space, hospital, or any other large concentration of electronic systems per 11.1.11.3), confirm Annex C's zonal bonding, shielded cabling and filter/SPD placement have been designed per ISO/IEC 30129 and IEC 61000.
- Confirm every exposed and extraneous conductive part in each EMC zone, including the neutral of any isolation transformer, is bonded to that zone's common bonding busbar.
- Treat any occurrence of Figures 23-25's patterns found during an audit or as-built review as a documented noncompliance, per the repeated NOTEs at Clauses 11.1.1, 11.2.1.3, 11.2.1.6, 11.3.1 and 11.4.2.3.
Try the numbers
Earth rod resistance estimator
- One rod
- –
- All rods in parallel
- –
- Minimum rod spacing
- –
R = ρ ÷ (2πL) × [ln(8L ÷ d) − 1], uniform soil, rods spaced at least one length apart. An estimate for planning; the design uses your measured soil model.
Maximum earth-fault loop impedance
- Trip current Ia
- –
- Design limit for Zs
- –
- Without the 2/3 margin
- –
Zs ≤ (2 ÷ 3) × U0 ÷ Ia for miniature circuit breakers to IS/IEC 60898, instantaneous trip. Every circuit and every source is checked, as CEA Reg 43(xii) requires.
What we find on audits
- Electrodes spaced closer than their own length, so extra rods add little
- Salt and charcoal backfill that corrodes the electrode within a few years
- Copper joined directly to galvanised steel in soil
- Separate earths for lightning, power and electronics left unbonded
- No test link, so the electrode cannot be measured without cutting a conductor
What you receive: the LPES Protection Passport
- As-built drawings of the installed system
- Risk assessment and design calculations
- Test results: earth resistance, continuity, SPD checks
- Component list with part codes and type-test references
- Inspection schedule for the protection level
Lightning to Load: one accountable partner
- Assess
- Design
- Specify
- Supply
- Implement
- Verify
- Assure
Standards basis
IS 3043:2026 · IEC 62305-3:2024 (Ed. 3) · IEC 60364-5-54 · IEEE 80-2013 · CEA Safety Regulations 2023 · IEC 62561 series · IS 732:2019 · IEC 60364-6:2016 · IEC 61936-1:2021
Reviewed by LPES engineering, November 2026. Clause and table numbers follow IEC 62305:2024 (Edition 3) and IS 3043:2026.
Questions engineers ask
How do I prove a site is part of a global earthing system?
By documenting the interconnections and showing by measurement or calculation that touch voltages stay within limits; the standard gives no single number. Earthing System Design
Does a global earthing system remove the need for a local electrode?
No. Each installation still has its own earthing system; the global effect allows that local system to be simpler. Mat / Grid Earthing for Substations
Which conductors make the interconnection?
Cable sheaths and screens bonded at both ends, dedicated earthing conductors and bonded metallic services. Earthing Conductors
What tests are needed?
Continuity of the interconnections, earth-fault loop impedance and touch voltage measurements. Earth-Fault Loop Impedance Test
Where are disconnecting links needed?
At earth bars, so that each local system can be isolated and measured without cutting conductors. Earth Bars & Terminals
Get this solution quoted for your site
Send the drawings or the basic dimensions. LPES returns the design parameters, the BOQ with part codes and the price in one offer.
