What is the earthing network?
The bare conductor and ground rods that run with the series circuit, giving lightning and fault currents a safe way to earth.
The earthing network is a system of bare conductors and ground rods laid along the series circuit. A counterpoise conductor runs in the trench with the primary cable, ground rods tie it to the soil at the regulator, the run ends and intervals, and bonding leads connect metal equipment to it.
It does two jobs. It gives lightning surge energy a path to earth that avoids the circuit cable and the lights, and it keeps exposed metal at a safe potential if a fault occurs. The network only works as one continuous path, so joints and rod connections are inspected and the earth resistance and continuity are tested.
Bare conductor and rods. Protects against lightning and faults.
Insulated conductor carrying the series circuit current. Not an earth path.
Frequently Asked Questions
Q1What is an earthing network in airfield ground lighting?
A system of bare conductors, ground rods and bonding connections laid along the series circuit and connected to the regulator and metal equipment. It gives lightning and fault currents a controlled path to earth.
Q2What is a counterpoise?
A bare conductor, usually copper, laid in the cable trench along the primary cable. It acts as a shield and an earth path, so lightning energy tends to flow along it rather than through the circuit cable.
Q3What are ground rods used for?
They connect the counterpoise to the soil at intervals and at the ends of runs, and at the regulator. The aim is a low resistance to earth so surge energy disperses quickly.
Q4What gets bonded to the earthing network?
Metal base cans, fixture housings, sign frames, transformer housings, pit covers and the regulator enclosure, as set by the design. Bonding keeps exposed metal at a safe potential during a fault.
Q5How is the earthing network checked?
By inspection of connections and by measuring earth resistance and continuity, at installation and again at intervals. Corroded or broken joints are the usual problem.
Q6Where are the earthing requirements defined?
In the applicable standard and design guidance, for example FAA AC 150/5340-30 and ICAO Aerodrome Design Manual Part 5, together with national electrical codes. Always confirm against the current edition and the project specification.
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