What is a bare copper earth conductor?
The uninsulated copper conductor laid in the cable trench — in contact with the soil, bonded to rods and equipment, and the path that carries lightning and surge current into the ground.
A bare copper earth conductor is an uninsulated copper conductor laid in the cable trench, usually with or above the primary cable. It is bonded to ground rods at intervals, to base cans and fixtures, and to the CCR earth bar, so the whole route shares one low-resistance path to earth. When it also gives lightning protection it is often called a counterpoise.
It is left bare so it touches the soil along its whole length and spreads lightning and surge current into the ground. It is not part of the series circuit: the lamp current flows only in the insulated primary cable loop. Its strength is in its continuity and its joints: a break or a corroded joint leaves part of the route without an earth path and may go unnoticed until a strike or a fault. Size, depth and joint type come from the design and the standard.
- Lay. Place the bare copper in the trench to the specified position and depth, clear of sharp stones.
- Keep it bare. Backfill with suitable material so the copper stays in contact with the soil.
- Bond. Make joints and connections to ground rods with exothermic welds or approved compression connectors on clean copper.
- Connect. Branch to base cans, fixtures and the CCR earth bar as the design shows.
- Protect. Fit warning tape, protect joints against corrosion and keep clear of other buried metal unless the design bonds it.
- Test & record. Earth continuity and earth resistance; log the readings and the as-built route.
Frequently Asked Questions
Q1What is a bare copper earth conductor in airfield ground lighting?
An uninsulated copper conductor, usually laid in the cable trench with or above the primary cable, that is bonded to earth electrodes and to equipment so the route has a low-resistance path to earth for lightning and surge current and for bonded metalwork. It is often called the counterpoise when it is installed for lightning protection.
Q2Why is the conductor bare rather than insulated?
Direct contact with the surrounding soil lets it act as a buried earth electrode and spreads lightning or surge current into the ground along its whole length. An insulated conductor can still link earth points, but it would not shed current into the soil along the route.
Q3Where is it installed?
Normally in the same trench as the primary cable, at the depth and position the design states, running the full length of the circuit and bonded to ground rods at intervals, to the fixture or base-can earth points, and to the CCR earth bar.
Q4How are the connections made?
With bonded joints that stay low resistance over many years, such as exothermic welds or approved compression connectors, made on clean copper and kept protected against corrosion. A twisted or loosely clamped joint is not acceptable.
Q5What problems can a bare copper earth conductor have?
Breaks in the conductor, corroded or loose joints, theft or damage during digging, and galvanic corrosion where the copper touches other buried metal such as steel or galvanised items. A broken conductor leaves part of the route without its earth path and can go unnoticed until a lightning strike or a fault.
Q6How is it checked?
By inspecting exposed lengths and joints during installation and maintenance, then testing earth continuity and earth resistance and comparing the readings with the commissioning baseline. Always follow the design and the site procedure.
Q7Does the bare copper conductor carry the lamp current?
No. The series circuit current flows only in the insulated primary cable loop from the CCR. The bare copper is not part of that loop: it stays at earth potential and only carries lightning, surge or fault current from bonded metalwork into the ground.
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