copper-bonded wire Ø 8 mm
- Project length
- 85.4 m
- Conversion
- 1 kg = 2.43 m
- Mass
- 35 kg
Material costenter a price
CBM / DESIGN ZONE
Ring earth calculator
Draw the building outline and place the down leads. Count the tape, joints and cost.
OUTLINE AND MATERIALS
Your ring earth plan
Choose an outline or draw one on the grid. You can change the dimensions with the mouse or in the fields.
Corners first, because lightning protection down conductors run there. Any extra leads go on the longest walls.
In addition to the section between the ring earth and the wall. Include the vertical run and the route to the clamp.
Edit corners
Corners P1, P2… are the points of the building outline on the 1 m grid plan (X to the right, Y down). Here you set the exact position of a corner from the building plan or add a new one when the outline has more bends (e.g. a bay or a U-shaped building). Whole wall lengths can also be changed in “Wall dimensions”.
TOP VIEW / 1 m GRID
4 pointsBuilding outline and ring earth
Drag a corner. Click a wall to change its length.
Wall dimensions
X marks horizontal walls in the drawing, Y vertical ones, S slanted ones. Type a length and press Enter: the wall end and the next corner move along it.
- m
- m
- m
- m
02Side sectionNon-insulated slab: ring earth and vertical rods
DIAGRAM · NOT TO SCALEVERTICAL RODS4 × 3.0 mRING FROM BUILDING1.0 mSLABnot insulated
VERTICAL RODS OR RING EARTH ONLY
Non-insulated slabEarth resistance
Don’t know the soil resistivity? Measure it with the Wenner method (step 1)
On the ring earth, corners first, next to the leads.
From 1 to 7 m in 0.5 m steps. The forged Ø 14.2 mm rod is joined from 1.5 m and 1 m sections.
10 Ω: PN-EN IEC 62305-3, per the CBM article.
VERTICAL RODS, WITHOUT THE RING
8.5 Ω
The rods meet 10.0 ΩOne rod 3.0 m34.13 ΩRods 4 × 3.0 m8.53 ΩArea inside the ring252.0 m² · re 9.0 m
- The result is the resistance of the vertical rods alone: R of one rod / n. With a combined electrode the ring and other horizontal electrodes are not included, because in practice the rods decide (agreed with CBM). The ring earth is calculated only when there are horizontal electrodes alone.
- Smallest rod spacing: 14.0 m. BS 7430 recommends at least twice the depth (6.0 m).
- Slab reinforcement is not included in the resistance, so the result is conservative.
RING EARTH AND LEADS INCLUDING RESERVE
85.4 m
Quantities from geometryRing earth length64.0 mConnection leads13.7 mOutline area192.0 m²
COST COMPARISON
Compare copper-bonded wire with galvanized tape on cost
Enter market prices per kilogram. In the background we convert kilograms to metres for the length of your project: 85.4 m (ring earth, leads and reserve).
galvanized tape 25 × 4 mm
- Project length
- 85.4 m
- Conversion
- 1 kg = 1.27 m
- Mass
- 67 kg
Material costenter a price
Conversion: galvanized 25 × 4 mm tape 1 kg = 1.27 m, copper-bonded Ø 8 mm wire 1 kg = 2.43 m (CBM slide, 10.2026); galvanized 30 × 4 mm tape 1 kg = 1 m (CBM article 06.2026); copper-bonded tapes per the mass table of the CBM cross-section calculator. Mass is counted in whole kilograms, as on the CBM slide. Example CBM prices from October 2026: galvanized tape 8.50 PLN/kg, copper-bonded wire 18.50 PLN/kg. CBM sells through distributors, so you enter market prices yourself.
Materials and cost
CBM products| Item | Quantity | Your price [EUR] |
|---|---|---|
| Variant: copper-bonded wire Ø 8 mm | ||
| Copper-bonded wire Ø 8 mm: ring earth and leadsC1110249 · length to order · mass in whole kg | 85.4 m · 35 kg | |
| Ring earth and connection lead joints1 on the closed ring + 4 leads · joints selected per the design | 5 pcs | |
| Variant: galvanized tape 25 × 4 mm | ||
| Galvanized tape 25 × 4 mm: ring earth and leadsfor comparison · length to order · mass in whole kg | 85.4 m · 67 kg | |
| Ring earth and connection lead joints1 on the closed ring + 4 leads · joints selected per the design | 5 pcs | |
| Common to both variants | ||
| Forged earth rod 14.2 mm / 1.5 mC0000175 · 4 × 3.0 m: 2 × 1.5 m sections per rod | 8 pcs | |
| Rod to ring earth clampSelected per the design | 4 pcs | |
Mass in whole kilograms, ring material prices per kg (no mass in the CBM data: per metre). Joints (copper-bonded wire Ø 8 mm): 1 on the closed ring earth + 4 connection leads.
copper-bonded wire Ø 8 mmPricing incompletegalvanized tape 25 × 4 mmPricing incomplete
Quantity plan: the ring earth is an offset of the outline sides with square corners. The joint count assumes full roll lengths in a closed loop and one connection per connection lead. Resistance is an estimate for uniform soil: with vertical rods the result is the rods alone (BS 7430), without rods the ring alone R = 0.6·ρ/√A (CBM article, consistent with DEHN). Cutting plan, additional joints, material selection and soil conditions must be checked in the design, and the resistance must be confirmed by measurement. The tool does not confirm compliance with standards.
RING EARTH CALCULATOR · PLAN AND RESISTANCE
Ring earth plan: non-insulated slab
- Date
Resistance: vertical rods8.5 ΩOne rod 3.0 m: 34.13 Ω · 4 × 3.0 m: 8.53 ΩMeets 10.0 Ω
- Foundation slab
- not insulated
- Building outline
- 192.0 m² · 56.0 m
- Ring earth
- 64.0 m · A = 252.0 m²
- Distance from building
- 1.0 m
- Ring earth material
- Ø 8 mm / 25 × 4 mm · 85.4 m
- Connection leads
- 4 pcs · +2.0 m
- Soil resistivity ρ
- 100.0 Ω·m
- Vertical rods
- 4 × 3.0 m · Ø 14.2 mm
Building Ring earth Connection lead (L) Vertical rod
ROT = 0,6 · ρ / √A (M. Łoboda, R. Marciniak, CBM article 06.2026, Table 1; consistent with DEHN, tab. 5.5.1) · Rr = ρ / (2πL) · [ln(8L/d) − 1] (BS 7430:2011, cl. 9.5.3, d = 14.2 mm) · result = Rr / n, the rods alone: with a combined electrode the ring and horizontal electrodes are not included (agreed with CBM); the ring is calculated only without rods.
Slab reinforcement is not included in the resistance. Preliminary calculation for uniform soil; the result must be checked in the design and by measurement after installation. Schematic drawing, dimensions come from the parameters.
RING EARTH CALCULATOR · SIDE SECTION
Ring earth plan: non-insulated slab
- Date
02Side sectionNon-insulated slab: ring earth and vertical rods
DIAGRAM · NOT TO SCALEVERTICAL RODS4 × 3.0 mRING FROM BUILDING1.0 mSLABnot insulated
Cost comparison: galvanized tape and copper-bonded wire
| Material | Length | Mass | Price / kg [EUR] | Cost [EUR] |
|---|---|---|---|---|
| copper-bonded wire Ø 8 mm | 85.4 m | 35 kg | ||
| galvanized tape 25 × 4 mm | 85.4 m | 67 kg |
Kilogram to metre conversion from CBM data, mass in whole kilograms. The designer enters market prices.
Bill of materials
Quantities are a geometric suggestion; cutting plan, joints and fittings are agreed in the design. The designer enters prices from the CBM distributor’s offer.
| Item | Catalogue no. | Quantity | Price [EUR] | Value [EUR] |
|---|---|---|---|---|
| Variant: copper-bonded wire Ø 8 mm | ||||
| Copper-bonded wire Ø 8 mm: ring earth and leads | C1110249 | 85.4 m · 35 kg | ||
| Ring earth and connection lead joints | 5 pcs | |||
| Variant: galvanized tape 25 × 4 mm | ||||
| Galvanized tape 25 × 4 mm: ring earth and leads | 85.4 m · 67 kg | |||
| Ring earth and connection lead joints | 5 pcs | |||
| Common to both variants | ||||
| Forged earth rod 14.2 mm / 1.5 m | C0000175 | 8 pcs | ||
| Rod to ring earth clamp | 4 pcs | |||
| No complete price: copper-bonded wire Ø 8 mm | ||||
| No complete price: galvanized tape 25 × 4 mm | ||||
NEXT STEP 3 OF 3
Go to step 3 Earthing calculator
Calculate the resistance of an earth rod arrangement, compare variants and list the materials.