Controlled procedures for AGL earthing, equipotential bonding, earth grid and electrode installation, earth resistance and continuity testing, lightning protection and surge protection device (SPD) inspection, lightning-damage assessment and periodic earthing verification. Applicable SOP range: SOP-301 to SOP-320.
Golden Rule — Earthing is not simply a low-resistance measurement. A safe AGL earthing system requires the correct architecture, reliable protective conductors, sound equipotential bonding, verified earth connections, effective lightning/surge protection and traceable testing. Every measured value must be interpreted against the approved design, test method and applicable acceptance criteria.
To ensure metallic AGL equipment is safely connected to the approved earthing system and that fault currents have an appropriate return path.
All required exposed conductive parts shall be connected to the approved protective/equipotential bonding system.
To establish a controlled procedure for protective earthing of Constant Current Regulators.
Critical Check — CCR protective earth shall not be treated as optional equipment grounding. The cabinet and applicable internal/external conductive parts shall follow the approved earthing design.
To ensure applicable metallic parts associated with AGL isolation transformers are correctly bonded/earthed according to the approved design.
Important — Do not create an unintended connection between isolated AGL series-circuit conductors and earth. Isolation-transformer circuit architecture must be preserved.
To establish requirements for protective earthing/bonding of illuminated airfield signs where required by the approved design.
To ensure metallic fixture assemblies are bonded where required by the approved electrical design.
To establish the bonding requirements for metallic base cans and associated conductive components.
Critical Point — Base-can bonding shall follow the approved AGL earthing architecture and shall not inadvertently compromise the isolation of the series circuit.
To establish a controlled procedure for installation of an approved earth grid/network.
Verify:
To ensure earth electrodes are installed at approved locations and in accordance with the earthing design.
To establish a standardized method for measuring earth resistance.
Verify:
Important — Earth resistance results can be affected by soil conditions, electrode configuration and parallel earth paths. The test method and acceptance criteria must therefore be defined before testing.
To verify that required protective-earth conductors provide electrical continuity.
To verify continuity between metallic components that are required to be equipotentially bonded.
To inspect lightning-protection components and associated connections for physical and electrical integrity.
To verify the condition and status of Surge Protection Devices (SPDs).
To establish a controlled procedure for replacement of defective or operated surge protection devices.
Critical Rule — Never replace an SPD with a device having a different electrical specification merely because it physically fits.
To establish a systematic inspection following suspected or confirmed lightning activity.
To verify AGL system integrity after a lightning event before returning affected equipment to normal service.
To maintain accessible earth pits/test chambers in safe and serviceable condition.
To verify physical and electrical integrity of earth connections.
To establish a controlled format for recording earthing and bonding test results.
Test records shall be traceable to the actual equipment/earth point and retained according to the airport's document-control requirements.
To establish a periodic program for checking the continued integrity of AGL earthing and bonding systems.
Review:
The master earthing workflow, lightning event response workflow, quality hold points, common failure modes, the master earthing checklist and the golden rule that governs all 20 Division 15 procedures.
For AGL earthing, bonding and lightning-protection systems:
Following a lightning event or suspected strike affecting AGL equipment:
"Earthing is not simply a low-resistance measurement. A safe AGL earthing system requires the correct architecture, reliable protective conductors, sound equipotential bonding, verified earth connections, effective lightning/surge protection and traceable testing. Every measured value must be interpreted against the approved design, test method and applicable acceptance criteria."
Technical references behind the procedures in this division:
References are given at document or chapter level for technical orientation. Confirm the current edition, amendments and national adoption (for example DGCA CAR Section 4, FAA Advisory Circulars or EASA material) for each project. Approved project specifications, manufacturer instructions and the airport's own procedures take precedence, as stated in the precedence note above.
Quick answers about Earthing, Bonding & Lightning Protection SOPs in the AGL SOP Library.
Division 15 is a set of 20 procedures (SOP-301 to SOP-320, Rev 0) for AGL earthing, equipotential bonding, earth grid and electrode installation, earth resistance and continuity testing, lightning protection and surge protection device (SPD) inspection, lightning-damage assessment and periodic earthing verification.
No. The Golden Rule says a safe AGL earthing system needs the correct architecture, reliable protective conductors, sound equipotential bonding, verified connections, effective lightning and surge protection, and traceable testing. Every measured value must be interpreted against the approved design, test method and acceptance criteria.
Approved earthing design, earth grid and electrode installation, earth connections, equipment bonding, then CCR, transformer, sign, fixture and base-can earthing or bonding. Then continuity testing, earth resistance testing, lightning protection and SPD inspection, system acceptance and periodic verification.
Verify the approved test method, calibrated instrument, correct leads, suitable conditions and isolation from parallel paths where required. Confirm no thunderstorm or lightning activity nearby, and suspend work on earthing and lightning-protection conductors when lightning is forecast or observed. Measure using the approved method, repeat where required, record and compare against criteria (SOP-309).
The SPD status indicator, physical damage, overheating, discoloration, loose terminals, wiring, the associated protective device, the earth connection and any replacement indicator. Defective SPDs are replaced using the approved procedure and the condition recorded (SOP-313).
Follow SOP-316 before returning equipment to service. Review ALCMS alarms and events, then inspect CCRs, series circuits, transformers, fixtures, signs, connectors, SPDs and earthing or bonding. Isolate affected series circuits and perform insulation-resistance testing with the CCR disconnected before re-energization, then run electrical, functional and operational lighting tests, replace damaged components and release after acceptance.
SOP-320 reviews previous results and trends, inspects accessible earth connections, and checks CCR earthing, transformer, fixture, base-can and sign bonding, earth pits, electrodes, the earth grid, any counterpoise conductor, lightning protection and SPDs. It performs continuity and earth-resistance tests on the approved schedule and compares results with approved criteria.
Knowing the testing procedure is essential. Understanding how earthing, bonding and lightning protection actually safeguard AGL equipment takes deeper technical knowledge.
Learn through structured training covering:
Develop the technical foundation to work with AGL systems systematically, safely and confidently.
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