AS/NZS 3000:2018
Table 5.1, copper
Minimum earthing conductor size by active conductor size
The loop impedance and cable size tools read the smallest earthing conductor for the active conductor size. The earth size feeds straight back into the loop impedance sum.
Verified: read against the printed standard, pages 278–279. Checked 27 Sept 2026.
Units: Active mm², Earth mm²
These are the values AmpSize encodes. No text of the standard is reproduced. Verify against the current standard.
20 rows
| Active (mm²) | Earth (mm²) |
|---|---|
| 1 | 1 |
| 1.5 | 1.5 |
| 2.5 | 2.5 |
| 4 | 2.5 |
| 6 | 2.5 |
| 10 | 4 |
| 16 | 6 |
| 25 | 6 |
| 35 | 10 |
| 50 | 16 |
| 70 | 25 |
| 95 | 25 |
| 120 | 35 |
| 150 | 50 |
| 185 | 70 |
| 240 | 95 |
| 300 | 120 |
| 400 | 120 |
| 500 | 120 |
| 630 | 120 |
Tools that read it (7)
Guides and learn pages that cite it (15)
- Lighting circuit loop impedance, B curve 10 A
- Maximum Zs for a 16 A curve C breaker
- What size cable for a 22 kW EV charger?
- What size cable for a lighting circuit in NZ?
- What size cable for power points in Australia?
- What size cable for power points in NZ?
- Max cable length for a 20 A C curve subcircuit
- Fault level at a sub‑board, 300 kVA transformer
- Shed earthing on a 16 mm² submain
- What size breaker for 4 mm² cable
- AmpSize vs jCalc vs free cable sizing tools
- AS/NZS 3000 Table 8.1: max Zs by curve and rating
- Earth fault loop impedance and maximum Zs
- Checking an existing circuit
- Prospective fault current at a board