The protective-electrical-integrity backbone of the handbook. This division maintains a reliable low-impedance path for fault current, equipment bonding, electrical safety, lightning-related currents, and surge protection — keeping AGL equipment and personnel protected.
Core principle: earthing provides the path — bonding connects the assets — surge protection limits transient overvoltage.
Philosophy: a visually intact earth conductor does not automatically mean the earthing system is electrically satisfactory. The maintenance program combines visual, mechanical, and connection inspection with continuity and earth-resistance verification before any corrective action is closed out.
Every earthing and bonding maintenance task in this division follows the same underlying sequence, regardless of asset type.
A generic five-class condition scale for the earthing and bonding system.
| Condition | Description | Action |
|---|---|---|
| Good | Earth / bonding system intact | Routine PM |
| Acceptable | Minor deterioration with no significant impact | Monitor |
| Deteriorating | Developing corrosion / mechanical issue | Planned maintenance |
| Defective | Continuity or physical integrity compromised | Corrective maintenance |
| Critical | Major loss of protective path or significant lightning/surge concern | Priority / emergency response |
The standard finding-to-action mapping used across the earthing and bonding system.
| Finding | Typical Maintenance Action |
|---|---|
| Dirty earth pit | Clean |
| Damaged pit cover | Repair / replace |
| Loose earth terminal | Tighten |
| Corroded connection | Clean / treat / replace |
| Damaged earth conductor | Repair / replace |
| Damaged earth clamp | Replace |
| Earth continuity failure | Locate and correct |
| Abnormal earth resistance | Investigate and correct |
| Loose bonding connection | Tighten |
| Damaged bonding conductor | Replace |
| Missing bonding connection | Restore |
| Damaged lightning conductor | Repair / replace |
| Failed SPD | Replace |
| Lightning-event damage | Inspect / test / restore |
| Corroded bonding connection | Treat / replace |
| Damaged cable-tray bonding | Restore |
Grouped by protective system — click any topic to expand its inspection points and acceptance condition.
Where not accessible: inspect the accessible connection and associated earth-pit arrangement instead.
Objective: cleaning should allow safe access to the earth connection.
Outcome: the restored pit should permit future inspection and testing.
Focus: particular attention should be given to exposed portions.
Standard: replace damaged or severely deteriorated conductors using the approved conductor specification.
Determine: whether the connection remains serviceable after cleaning.
Standard: use the applicable manufacturer / installation requirements for tightening.
Defective clamps should be repaired or replaced.
Objective: confirm that the intended earth connection remains electrically continuous.
Where bonding is by equipment design: verify it remains intact after maintenance.
Focus: particular attention after civil or fixture replacement work.
Applies: where metallic cable trays are used and bonding is required.
Where fitted: verify the SPD's visual status indicator condition.
Replace when: the status indication or condition shows failure or end of life, or when inspection / testing after a surge or lightning event shows the device is degraded.
Look for: both visible damage and abnormal electrical / test conditions.
Important: acceptance limits should come from the applicable project specification, airport standard, equipment requirement, or governing standard — not from an arbitrary universal value. Safety: apply the site isolation / permit procedure before disconnecting any earth link for testing, and do not carry out earth testing or work on lightning-protection conductors during thunderstorm activity.
Objective: confirm the intended conductive path has not been interrupted.
Trigger: a failed or abnormal earth test should initiate a controlled investigation — see the full sequence below.
The controlled investigation sequence triggered by an abnormal or failed earth test result.
Failed or unexpected earth-test value.
Confirm the test was correctly configured.
Confirm calibration and correct operation.
Confirm the result is genuine.
Check the earth connection point.
Check for damage or corrosion.
Check the earth electrode and pit.
Check the associated bonding path.
Determine the root cause of the deviation.
Repair, clean, treat, or replace as required.
Confirm the correction restored acceptable values.
Close out with the final measured value.
Earthing and bonding work does not stand alone — it should be triggered by wider events and verified after other maintenance disturbs it.
Why it matters: maintenance work elsewhere on the asset can unintentionally disturb an otherwise satisfactory bonding path — the exact testing requirement should correspond to the work performed.
Division 16 reduces to a single protective chain, reinforced by lightning and surge protection.
Quick answers about earthing & bonding maintenance, based on the topics in this division.
It is the protective-electrical-integrity division, maintaining a reliable low-impedance path for fault current, equipment bonding, electrical safety and lightning-related currents. In short, earthing provides the path, bonding connects the assets and surge protection limits transient overvoltage.
Division 16 (Earthing & Bonding Maintenance) contains 31 topics in four groups: Group A Earthing System (10 topics), Group B Equipment Bonding (10 topics), Group C Lightning / Surge Protection (6 topics) and Group D Testing (5 topics).
No. A visually intact conductor is not automatically electrically satisfactory, so the maintenance sequence goes beyond inspection to continuity verification and earth-resistance verification.
Visual Inspection, Mechanical Inspection, Connection Inspection, Continuity Verification, Earth-Resistance Verification, Corrective Action, Retest and Record.
A controlled twelve-step investigation: verify the test setup and the instrument, repeat the test to confirm the result, inspect the connection, conductor, electrode and pit and the bonding path, identify the cause, correct the defect, repeat the test to confirm acceptable values, and record the final measured value.
A lightning event, a major electrical fault, flooding, civil works, replacement of a cable, fixture, sign or transformer, and CCR maintenance or panel modification. Earthing and bonding should also be verified after other maintenance disturbs it.
Five classes: Good (routine PM), Acceptable (monitor), Deteriorating (planned maintenance), Defective (continuity or physical integrity compromised, corrective maintenance) and Critical (major loss of the protective path or a significant lightning or surge concern, priority or emergency response).
A loose earth terminal or bonding connection is tightened, a corroded connection is cleaned, treated or replaced, an earth continuity failure is located and corrected, abnormal earth resistance is investigated and corrected, a failed SPD is replaced, and lightning-event damage is inspected, tested and restored.
Earthing and bonding maintenance is more than an annual resistance reading.
Build the technical knowledge to understand fault current paths, bonding continuity, soil resistivity effects, and how a degraded earth system compromises personnel and equipment safety.
Maintain the earth. Protect the fault path. Understand the risk.
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