Earthing systems · Complies to IEC 62305-3 §5.4
Ring Earth Electrode (Type B)
A ring earth electrode (Type B arrangement in IEC 62305-3) is a conductor buried in a closed loop around a structure, at least 0.5 m deep and about 1 m from the outer walls. It equalises potential around the building and gives every down conductor a short path to earth.
LPES solution codeRNG
Governing standardIEC 62305-3 §5.4
LPES design ruleRing at least 1 m out and 0.5 m deep; stainless steel 316, copper-bonded or copper in soil
When it applies
- Existing buildings where a foundation electrode cannot be added
- Structures with electronic systems or a high fire risk, where potential equalisation around the building matters
- Rocky or high-resistivity ground where single rods cannot reach the target resistance
- Buildings with insulated or waterproofed foundations
When it does not
- Sites with no access around the perimeter (party walls on all sides) — use rod earthing at each down conductor
- Small isolated structures where two rod electrodes meet the requirement at lower cost
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 |
|---|---|---|
| Arrangement | Closed ring with at least 80% of its length in contact with soil | IEC 62305-3 Cl. 5.4 |
| Depth and offset | At least 0.5 m deep and about 1 m outside the external wall | IEC 62305-3 Cl. 5.4 |
| Mean radius | Not less than the minimum electrode length l1 for the lightning protection level; add rods where it is | IEC 62305-3 Cl. 5.4 |
| Conductor | Copper tape or stranded 50 mm², or galvanised steel strip 30 × 3.5 mm; stainless steel in aggressive soil | IEC 62561-2 |
| Target earth resistance | 10 Ω or lower recommended, measured at low frequency | IEC 62305-3 · IS 3043 |
| Test points | One test joint where each down conductor meets the ring | IEC 62305-3 |
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 | Ring conductor and tails to each down conductor | Building perimeter + 8 m (1 m offset) + 2 m per down conductor |
| Earth Rods | Supplementary vertical rods where the ring radius or resistance falls short | One rod per down conductor where required by the calculation |
| Exothermic Welding | Buried joints at ring closures, tees and rod heads | One joint per tee, rod and ring closure |
| Test Joints & Inspection Housings | Disconnection point between each down conductor and the ring | One per down conductor |
From design to handover
- Survey soil resistivity and buried services along the trench line
- Calculate ring length, radius and any supplementary rods for the protection level
- Trench to 0.5 m or deeper, lay the conductor and make welded joints
- Connect each down conductor through a test joint and backfill with fine soil
- Measure earth resistance with the test joints open and closed, and record both
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 | A buried earth grid is laid at least 500 mm deep, and the ring is bonded to the reinforcement every 5 m to 10 m, 5 m for buildings with information technology or telecom equipment. |
| IS 3043:2026 | Clause 12.1.2.1, 13.7 | For lightning protection, a Type A earth electrode targets a resistance below 10 Ω, and the continuity of the lightning protection path is checked against 0.2 Ω. |
| IS 3043:2026 | Table 26, Table 27 | Electrode sizes shall follow Table 26 and materials should follow Table 27. Copper, stainless steel or copper-bonded steel is used below 50 Ω·m and in coastal areas. Aluminium is not used in soil or concrete. |
| 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. |
| CEA Safety Regulations 2023 | Reg 43(ix) | An earthing system must carry the prospective earth-fault current within temperature limits, keep earth-fault loop impedance low enough to operate the protective device in time, stay mechanically strong and corrosion resistant for the life of the installation, and be tested for effective bonding before energisation. |
| CEA Safety Regulations 2023 | Reg 43(x), Reg 50(8) | Earthing systems are tested for resistance on a dry day in the dry season at least once a year, and the records are kept for the Electrical Inspector. |
| 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 60364-6:2016 | Annex C | Earth electrode resistance is measured by fall-of-potential with auxiliary electrodes, by a loop impedance instrument, or by current clamps where auxiliary electrodes cannot be placed. |
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.
IEC 62305-3:2024 · LPES Knowledge Hub H-49
Testing of an LPS
A lightning protection system cannot be judged by how it looks. Once it is installed, the only way to know whether the down-conductor network still carries a continuous path from air termination to earth, and whether the earth-termination system still disperses current the way it was designed to, is to test it: continuity testing of the conductors and bonding, and resistance measurement of the earth electrodes and the earth-termination system as a whole. IEC 62305-3:2024 treats this electrical testing as a defined, recurring activity — not a one-off commissioning formality — with its own acceptance guidance, its own interval logic, and its own place in the inspection record.
How it is applied
- Read together, Clause 5.3.6, Clause 7 and Annex D.7.3 describe a repeatable field sequence:
- Confirm there is no threat of thunderstorms before starting (Clause 7.1) — testing and inspection are not conducted while that threat exists.
- Gather the LPS design report, drawings and previous inspection/maintenance reports, so every test joint, test point and electrode location is known before going to site (Annex D.7.2.1, D.7.3).
- Locate the test joint fitted at the base of each down conductor (or the test point, where the down conductor is an embedded component combined with a foundation electrode) and open it with the correct tool — it should otherwise remain closed in normal use (Clause 5.3.6).
- Continuity-test each down conductor and its bonding connections, giving particular attention to parts of the LPS that are not visible for inspection (concealed or embedded runs) (Annex D.7.3). Confirm that continuity tests have also been carried out for any new bonding or services added since the last inspection (Annex D.7.2.4).
- With the test joint open, measure the earth resistance of the individual electrode, and — where possible — of the earth-termination system as a whole, using a measurement frequency different from the power-supply frequency and its multiples (Clause 5.4.1, 5.4.2.2).
- For an earth network that combines vertical rods with a partial or full ring electrode, perform the disconnection and test at the earth inspection pit; where that is impractical, use a high-frequency or impulse test method instead of the low-frequency disconnection method (Annex D.7.3 Note 2).
- Compare the whole-system reading against the 10 Ω guide value. If it exceeds 10 Ω, check the electrode lengths against Figure 5 — unless the electrodes are in rocky soil, where the 10 Ω requirement does not apply and the rocky-soil installation requirements are checked instead.
- Compare each Type A electrode's individual reading against its neighbours; flag any pair differing by more than a factor of 2.
- Compare this reading against the trend from previous inspections; investigate the cause of any significant increase or decrease, even where the current reading still passes.
- Where the earth-termination system does not conform, or cannot be verified from the available information, improve it — additional electrodes, or a new earth-termination system — rather than leaving the finding open.
- Test any SPD that lacks a visual status indicator, preferably using the manufacturer's guidelines or equipment.
- Close the test joints once measurement is complete, and record every result — continuity outcome, resistance values, method and conditions used, and any corrective action — filed together with the LPS design and inspection/maintenance records (Clause 7.4, Annex D.7.4).
Common mistakes
- Treating a visual-only walk-round as proof that the earth-termination system and down-conductor network are sound — continuity loss and rising earth resistance are not visible.
- Testing with equipment or at a frequency that is not separated from the power-supply frequency and its multiples, picking up interference and producing an unreliable reading.
- Recording only the parallel earth-termination-system resistance and never the individual electrode readings — this can mask a single failing electrode inside an otherwise healthy network.
- Skipping the continuity test on bonding added for a new service or addition since the last inspection, leaving an unverified path in the record.
- Carrying out testing, inspection or maintenance work during the threat of thunderstorms.
- Applying the 10 Ω guide value to earth electrodes in rocky soil, where that requirement does not apply and the rocky-soil installation requirements govern instead.
- Leaving a test joint open after measurement — in normal use it should remain closed.
- Reviewing this inspection's readings in isolation, without comparing them against the trend from previous inspections, and so missing a rising-resistance pattern that is itself a fault signal.
- Overlooking SPDs that have no visual status indicator, which need their own functional test rather than being assumed sound because nothing looks wrong.
- Assuming a complete inspection with electrical testing was done because a visual inspection happened — the standard is explicit that visual inspection and electrical testing are not the same activity and are not automatically both included.
Design checklist
- Confirm no thunderstorm threat before starting work
- Obtain the LPS design report, drawings and previous inspection/maintenance records
- Locate every test joint and test point on each down conductor
- Open each test joint with the correct tool
- Continuity-test each down conductor and bonding path, especially concealed sections
- Confirm continuity tests were completed for any bonding added since the last inspection
- Measure the earth resistance of each individual electrode
- Measure the earth resistance of the earth-termination system as a whole, where possible
- Use a measurement frequency different from the power frequency and its multiples
- For combined vertical-rod/ring networks, test at the earth inspection pit, or use a high-frequency/impulse method if disconnection is impractical
- Compare the whole-system resistance against the 10 Ω guide value (note the rocky-soil exception)
- Compare each Type A electrode's reading against its neighbours (flag a factor-of-2 spread)
- Compare readings against previous inspections; flag any significant change, increase or decrease
- Test any SPD without a visual status indicator
- Close each test joint after measurement
- Record continuity and resistance results, conditions used, and any corrective action taken
- File results with the LPS design and inspection/maintenance records
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.
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
What is the difference between Type A and Type B earthing?
Type A uses separate rods or radials at each down conductor. Type B is a closed ring or foundation electrode that links all down conductors and equalises potential. Deep / Rod Earthing (Type A)
How deep should a ring earth electrode be buried?
At least 0.5 m, and deeper where frost or drying of the top soil would raise its resistance. Earthing Conductors
Which material lasts longest in soil?
Copper and stainless steel last longest. Galvanised steel is acceptable in non-aggressive soil but must not be joined to copper or to steel in concrete without corrosion protection. Earthing Conductors
Do I still need rods with a ring?
Only where the ring's mean radius is smaller than the minimum length required for the protection level, or where the measured resistance is too high. Earth Rods
How is the ring tested?
By a fall-of-potential earth resistance test, with each down conductor isolated at its test joint in turn. Earth Resistance Testing
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.
