What is earthing maintenance?
Keeping the earthing system effective for the day insulation fails — connections clean and tight, bonds continuous, earth pits accessible and ground-rod resistance checked against the commissioning record, so fault current always has a low-resistance path to earth.
Earthing is the safeguard for the day insulation fails, and it fails quietly. Earthing maintenance keeps it working: the bond leads, jumpers and clamps are clean and tight, the earthing conductor is continuous, the earth pits are accessible with their test links in good order, and the ground-rod resistance is measured and compared with the commissioning record.
Buried joints corrode, excavation cuts conductors and soil resistance moves with the weather, so none of this shows until a fault. The series-circuit conductors stay insulated from earth, so any earth connection found on them is a fault, not an earth. Before a test link is opened or an earth or bond is disturbed, the circuit is isolated, locked out and proved dead; the connection is then restored and checked before the circuit goes live again.
- Isolate. Circuit off, locked out and proved dead before any link is opened or any earth is disturbed.
- Look. Check bonds, lugs, clamps and pit covers for corrosion, looseness and damage; clear water and debris.
- Test continuity. Measure the low resistance of bonds and the earthing conductor.
- Measure the rod. Use the earth tester, with the test link opened as the site procedure requires.
- Repair. Clean to bright metal, remake with the correct fittings, protect against corrosion and retest.
- Restore & record. Close the link, restore the circuit, compare with the commissioning record and log the readings.
Frequently Asked Questions
Q1What is earthing maintenance in airfield ground lighting?
Earthing maintenance is the routine inspection, testing and repair of the earthing system that protects people and equipment on an AGL installation. It covers the bonding leads and jumpers, the earthing conductor, the earth-pit connections and the ground rods, and proves they still give fault current a low-resistance path to earth.
Q2Why does buried earthing need regular maintenance?
Earthing fails quietly. Clamps and lugs corrode or work loose, conductors can be cut by excavation, pits fill with water or debris, and soil resistance changes with moisture and season. Nothing shows until a fault occurs, so the system is inspected and tested on a schedule to find problems first.
Q3What is checked during earthing maintenance?
A visual check of bonding leads, jumpers, lugs, clamps and pit covers; a low-resistance continuity test of bonds and the earthing conductor; and an earth-resistance measurement of the ground rods with an earth tester. Results are compared with the commissioning record and earlier readings.
Q4Why isolate the circuit before opening a link or disconnecting an earth?
The earth connection is the safeguard that makes a fault safe, and the series circuit carries live current while it is on. The circuit is isolated, locked out and proved dead under the permit-to-work before any test link is opened or any earth or bonding connection is disturbed, and the connection is restored and checked before the circuit is re-energised.
Q5How is earth resistance measured, and what value is acceptable?
An earth tester measures the rod's resistance using the method in the instrument's instructions and the site procedure, with the test link opened as that procedure requires. The acceptable value comes from the design, the applicable electrical code and the commissioning record. A reading that is steadily rising is an early warning even if it is still within limits.
Q6What if a reading is high or a connection is corroded?
Clean the joint back to bright metal, remake it with the correct fittings, protect it against corrosion as specified and test again. If the reading is still high, refer it to the person responsible for the earthing design, since the fix may be more rod or a change to the earth pit. Do not test during a thunderstorm, and record the defect and the action.
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