What is earthing inspection?
A close look at the bonds, clamps, earth pits, ground rods and conductor that give fault current and lightning a safe path to earth, checking for corrosion, damage and breaks before they are needed. An earth can look perfect and still be open.
The earthing network is the bare conductor, ground rods and bonding leads laid along the series circuit. It gives fault current and lightning a low-resistance path to earth and keeps exposed metal safe to touch. It does nothing until the day it is needed, so it fails quietly: buried joints corrode, digging cuts conductors and clamps work loose, while everything still looks normal. Inspection checks that the path is physically there. The insulated series-circuit cable is not an earth path, so an earth contact found on it is a fault, not an earth.
1Look from the surface first
A lot can be seen without opening anything. Check the bonding leads on the CCR, signs, base cans and metal covers, and confirm each still touches the metalwork it is meant to protect. Check that earth-pit covers are present, sound and reachable, and look along the route for digging, erosion or new works, and for any exposed or lifted conductor. Work on the airfield only with the right permission and under the site’s safety rules.
2Look, do not disturb
An earth conductor can carry fault current, so an earth is never opened, loosened or disconnected while the equipment it protects is energised. Inspection looks and records; opening a pit or a test link is done under the permit and isolation your procedure requires, and nothing is worked on in a thunderstorm. In the pit, note water, silt or debris, then check the test link, the rod clamp and every lug and fastener for corrosion, looseness or damage.
- Look before touching anything
- Photograph defects where they are
- Log against position and circuit
- Disconnect an earth with equipment energised
- Assume a clean joint means low resistance
- Leave a cut or missing earth unreported
3Record and act
Photograph each defect and log it against its position and circuit. Inspection shows what can be seen; continuity and ground-rod resistance tests prove the electrical condition, and cleaning, remaking and protecting joints is earthing maintenance. A cut conductor or a missing bond on exposed metalwork is raised promptly, because the equipment may be unprotected until it is put right. Close the pit and restore the circuit only as your procedure allows.
| Check point | What to look for |
|---|---|
| Bonding leads | On the CCR, signs, base cans and metal covers: present, undamaged, touching the metalwork, not stretched |
| Lugs and clamps | Corrosion, looseness, cracked, burned or missing fasteners |
| Earth pit and cover | Cover present and sound, access clear, water or debris inside |
| Test link | In place, closed, clean and labelled |
| Ground-rod connection | Clamp tight, no heavy corrosion, rod head intact |
| Counterpoise conductor | Visible runs intact: no cuts, exposed or lifted lengths |
| Joints | Corroded, cracked or burned, wrong or mixed fittings |
| Route | Signs of digging, erosion or new works over the conductor |
| Record | Dated photo, position, circuit, finding and action |
Frequently Asked Questions
Q1Why is the earthing network inspected?
Earthing does nothing until a fault or lightning strike, so a failure stays hidden. Buried joints corrode, digging cuts conductors and clamps work loose, yet the system still looks normal. Inspection checks that the path to earth is physically there and in good condition before it is needed.
Q2Can earthing be inspected while the circuit is live?
The visible parts can be looked at from outside: bonding leads, covers, pit lids and signs of digging. An earth connection is never opened, loosened or disconnected while the equipment it protects is energised, and an earth conductor can carry fault current, so it is treated with care. Opening a pit or a test link is done under the permit and isolation your procedure requires.
Q3What defects should be looked for?
Look for corroded, cracked or burned joints, loose or missing clamps and fasteners, a bonding lead that is damaged, stretched or no longer touching the metalwork, a cut, exposed or lifted counterpoise conductor, a damaged or missing pit cover, water or debris in an earth pit, an open or missing test link and signs of excavation along the route.
Q4Is inspection the same as earthing testing or maintenance?
No. Inspection finds and records the visible condition. Testing measures bond continuity and ground-rod resistance, and maintenance cleans, remakes and protects the connections. A joint can look sound and still read high, so an inspection finding often leads to a test or a repair, and a clean inspection does not replace testing.
Q5What happens after a defect is found?
Photograph it, log it against the position and circuit, and raise the test, repair or replacement. A cut conductor or a missing bond on exposed metalwork is raised promptly, because the equipment may not be protected until it is put right.
See It. Understand It. Then Learn How to Engineer It.
Recognising an AGL system visually is the first step. The next step is knowing how to design, install, test, commission and maintain them correctly.
Build Practical AGL Engineering Skills
Go deeper with structured training from Precision AGL Academy, covering:
Learn how each light, sign and circuit works as part of a complete airport lighting system, not just as an isolated diagram.