Earthing systems by Golde

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GOLDE have several years’ experience installing lightning (earthing) protection systems in Queensland. 

Standard: AS/NZS 1768:2021

1. Scope

This specification covers the lightning protection earthing requirements for the facility, including electrodes, down-conductors, bonding, testing, and installation practices in accordance with AS/NZS 1768.

2. Earth Termination System

• Provide a dedicated earthing system using:
  • Copper-bonded earth rods (minimum 2.4 m long, 16 mm diameter)
  • Buried ring earth conductor around the structure (minimum 25 mm² copper)
• Minimum burial depth: 600 mm
• All earth components to be mechanically and electrically bonded.

3. Down-Conductors

• Minimum 35 mm² copper or 70 mm² aluminium
• Install a minimum of two down-conductors on opposite sides
• Keep conductors straight, direct, and avoid sharp bends (<90°)
• Bond down-conductors to the earth termination system using exothermic welds or rated mechanical clamps.

4. Earth Resistance / Impedance Criteria

• Target earth resistance: ≤ 10 Ω
• For critical structures (substations, telecom towers): ≤ 5 Ω preferred
• Earth system must provide a low-impedance path for lightning discharge.

5. Bonding Requirements

Bond the LPS earth to the following:

• Main electrical earth bar
• Structural steel
• Rebar cages (foundation earthing allowable)
• Metallic pipes (water/gas) entering the structure
• Lightning arrestor mounts and metallic roof components

All bonding to comply with equipotential requirements of AS/NZS 1768.

6. Electrode Installation Requirements

• Use copper-bonded rods, 2.4 m long minimum, installed vertically
• Multiple rods shall be spaced ≥ 2 × rod length apart
• Interconnect multiple electrodes using 25–35 mm² copper
• Ring earth conductors must be cadwelded or clamped as per AS/NZS 1768      requirements
• Backfill around rods with conductive soil/enhancement compound where necessary

7. Testing & Commissioning

Perform:

• Earth resistance test (fall-of-potential preferred)
• Continuity checks of all bonding
• Document soil resistivity results (if performed)
• Provide a commissioning report including:
  • Earth resistance values
  • Visual inspection records
  • As-built earthing layout
  • Clamp and weld certification

    

8. Materials

• Copper-bonded rods: 16 mm × 2400 mm minimum
• Conductor: 25–35 mm² bare copper or equivalent
• Clamps: Rated for lightning discharge (UL 96A / IEC / AS)
• Exothermic weld kits where used
• Pit lids: polymer or concrete with earth inspection point

9. Installation Drawings

Include:

• Earth ring routing
• Rod locations
• Bonding points
• Down-conductor paths
• Main earth bar location