AGL Cable Troubleshooting

Equipment / System

Primary series circuit cable (constant-current loop, typically 6.6A/8.3A/20A) connecting the CCR to the isolation transformers around the circuit.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before any work.
• Treat the primary series circuit as energised (up to several kV) until confirmed isolated at the CCR.
• Coordinate all airside access through ATC/apron control.

Diagnostic Procedure

1. ObservationCheck the CCR panel: an open primary series circuit typically shows the regulator driving toward maximum voltage while current collapses, tripping an open-circuit alarm.
2. ObservationDetermine which section of the circuit is affected using downstream fixture status.
3. MeasurementWith the circuit isolated, perform loop-by-loop continuity/resistance testing from accessible pull boxes.
4. MeasurementUse a TDR to estimate the distance to the break from the nearest accessible point.
5. DecisionBreak located at a joint pit → joint repair. Break mid-run in open cable → locate and repair via excavation.
6. Fault LocationIsolate the fault to the specific joint or cable section.
7. Root CauseConfirm full-loop continuity is restored before re-energising.

Test Points

Root Cause Verification

After repair, re-energise and confirm the CCR returns to normal voltage/current regulation with full loop continuity, and megger the repaired section.

Corrective Action

• Repair or replace the broken conductor or joint.
• Splice using an approved method rated for the cable type.
• Restore cable route marking if disturbed during repair.

Preventive Action

• Maintain accurate as-built cable route drawings.
• Require a utility locate before any excavation near the circuit.
• Schedule periodic loop continuity and insulation resistance testing.

Related References

SOP: SOP-CBL-01 (Primary Series Circuit Fault Location Procedure), SOP-CCR-04 (CCR LOTO Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I, IEC 60364

Diagram: Circuit route and joint pit schedule

Case Study: Division 01 — CCR Troubleshooting; Division 24 — Complete Runway Lighting Failure

Equipment / System

Secondary cable (single-core, low-voltage) between the isolation transformer secondary and the fixture, including its L-823 connectors.

Possible Causes

Required Tools

Safety Precautions

• LOTO before opening the base can.
• Confirm the isolation transformer secondary is de-energised before handling, even though it is low voltage.

Diagnostic Procedure

1. ObservationConfirm the primary series circuit current is normal, ruling out an upstream fault.
2. MeasurementWith the circuit isolated, check continuity of the secondary cable from the transformer secondary to the fixture.
3. MeasurementInspect the L-823 connector for a broken or corroded pin.
4. DecisionOpen found within the connector → replace the connector. Open found in the cable run → replace the secondary cable.
5. Fault LocationIsolate the fault to the connector or the cable.
6. Root CauseConfirm restored continuity end-to-end before re-energising.

Test Points

Root Cause Verification

Re-energise and confirm the fixture illuminates at the correct intensity across all steps.

Corrective Action

• Replace the broken secondary cable.
• Replace or reseat the L-823 connector.

Preventive Action

• Inspect secondary cable and connectors during fixture PM.
• Stock spare secondary cable assemblies.
• Properly support cable runs to avoid strain at the connector.

Related References

SOP: SOP-CBL-02 (Secondary Cable Fault Procedure)

Standards: FAA AC 150/5345-26 (L-823 connectors), ICAO Annex 14 Vol I

Diagram: Base can and secondary cable wiring diagram

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Primary or secondary cable insulation between conductors, or between adjacent conductors within a joint.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any testing.
• Treat a shorted circuit as a potential arc-flash/thermal hazard at the fault location.

Diagnostic Procedure

1. ObservationReview the CCR trip history for an overcurrent/short-circuit trip pattern.
2. MeasurementWith the circuit isolated, megger conductor-to-conductor and conductor-to-earth.
3. MeasurementUse a TDR to estimate the distance to the low-impedance fault.
4. DecisionShort isolated to a specific joint → joint repair. Short in an open cable run → excavate and repair.
5. Fault LocationIsolate the fault to the specific joint or cable section.
6. Root CauseConfirm insulation resistance is restored to an acceptable value.

Test Points

Root Cause Verification

After repair, megger the full loop, re-energise, and confirm the CCR regulates normally without tripping across a full operating cycle.

Corrective Action

• Repair or replace the shorted joint or cable section.
• Drain and reseal an affected joint pit.

Preventive Action

• Schedule periodic insulation resistance testing.
• Ensure joint pits drain properly.
• Use approved joint kits rated for the application.

Related References

SOP: SOP-CBL-03 (Short Circuit Fault Location Procedure), SOP-CCR-04

Standards: IEC 60364, FAA AC 150/5340-30

Diagram: Circuit route and joint pit schedule

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Primary series cable insulation relative to earth/ground, including joints, base cans, and any point exposed to moisture.

Possible Causes

Required Tools

Safety Precautions

• LOTO the CCR before any insulation testing or cable work.
• Treat a marginal insulation reading as a developing hazard rather than a nuisance trip.

Diagnostic Procedure

1. ObservationReview the CCR earth-fault trend to establish gradual degradation versus a step-change.
2. MeasurementMegger the primary cable in segments from accessible pull boxes, comparing each to its baseline.
3. MeasurementIdentify the segment or transformer contributing the greatest drop in insulation resistance.
4. DecisionDrop isolated to one segment/joint → localised repair. Drop distributed across many segments → treat as cumulative circuit ageing.
5. Fault LocationIsolate to the specific segment, joint, or transformer winding.
6. Root CauseConfirm with a full-loop re-test that the reading is restored to, or above, the acceptable threshold.

Test Points

Root Cause Verification

Re-megger the full loop after repair and monitor the CCR earth-fault trend over subsequent operating cycles.

Corrective Action

• Repair or replace the identified degraded cable segment or joint.
• Replace a transformer with the failing winding.
• Reseal an identified moisture entry point.

Preventive Action

• Schedule periodic full-loop insulation resistance testing and trend results year over year.
• Prioritise ageing circuit sections for proactive replacement.
• Seal known moisture entry points identified during PM.

Related References

SOP: SOP-CBL-04 (Earth Fault Location Procedure), SOP-CCR-04

Standards: IEC 60364, ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Circuit route drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Primary or secondary cable insulation system across its full length, including conductor jacket, joints, and terminations.

Possible Causes

Required Tools

Safety Precautions

• LOTO before testing.
• Fully de-energise before hipot testing given the higher test voltages involved.

Diagnostic Procedure

1. ObservationReview the test result against the previous baseline and the acceptable threshold for the cable type.
2. MeasurementSegment the circuit and megger each segment to localise the lowest-reading section.
3. MeasurementInspect the identified segment for visible jacket damage, joint condition, or chemical exposure.
4. DecisionFailure localised to a specific defect → targeted repair. Failure consistent across an aged section → plan proactive replacement.
5. Fault LocationIsolate to the specific cable section or joint.
6. Root CauseConfirm restored insulation resistance after repair.

Test Points

Root Cause Verification

Re-test the full loop after repair and confirm the reading is restored to, or above, the acceptable threshold.

Corrective Action

• Repair or replace the identified damaged cable section or joint.
• Replace a substandard joint kit installation.

Preventive Action

• Trend insulation resistance results year over year rather than relying on a single reading.
• Prioritise ageing sections for proactive replacement.
• Protect exposed cable from chemical and UV exposure.

Related References

SOP: SOP-CBL-05 (Insulation Resistance Test Procedure)

Standards: IEC 60364, ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Circuit route drawing with installation dates

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Full primary series circuit loop or a defined test segment, evaluated against the site's insulation resistance acceptance criteria.

Possible Causes

Required Tools

Safety Precautions

• LOTO before testing.
• Verify test equipment calibration before relying on a borderline reading.

Diagnostic Procedure

1. ObservationCompare the low reading against the historical trend for this circuit to rule out a test/technique anomaly.
2. MeasurementRepeat the test under confirmed isolation and calibrated equipment to validate the reading.
3. MeasurementSegment the circuit and test each segment to localise the contributing section.
4. DecisionReading confirmed low and localised → proceed to targeted repair. Reading low but distributed and trending gradually → schedule proactive maintenance rather than emergency repair.
5. Fault LocationIsolate to the segment, joint, or transformer contributing most to the reduced reading.
6. Root CauseConfirm with a repeat full-loop test after any corrective action.

Test Points

Root Cause Verification

Retest after any corrective action and confirm the reading is restored to, or trending toward, the acceptable range, then continue periodic monitoring.

Corrective Action

• Repair or replace the segment/joint identified as the primary contributor.
• Reseal a moisture entry point.
• Recalibrate test equipment if found to be the cause.

Preventive Action

• Schedule periodic full-loop insulation resistance testing on a defined interval and trend results.
• Note ground conditions alongside the result, avoiding testing immediately after heavy rain where practical.

Related References

SOP: SOP-CBL-05 (Insulation Resistance Test Procedure)

Standards: IEC 60364, ICAO Annex 14 Vol I

Diagram: Circuit route and joint schedule

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Full primary series circuit insulation system, evaluated for cumulative leakage current to earth across all joints, transformers, and cable sections.

Possible Causes

Required Tools

Safety Precautions

• LOTO before segment testing.
• Treat elevated leakage as a developing hazard warranting investigation rather than a nuisance reading.

Diagnostic Procedure

1. ObservationReview the leakage trend to determine whether it is a step-change or a gradual increase.
2. MeasurementSegment the circuit and megger each section, plus individually test transformer windings, to localise the dominant contributor.
3. MeasurementInspect above-ground terminations for surface contamination.
4. DecisionLeakage isolated to one segment/transformer → targeted repair. Leakage distributed across many segments → treat as cumulative ageing and plan proactive maintenance.
5. Fault LocationIsolate to the specific segment, joint, or transformer contributing most to the leakage.
6. Root CauseConfirm with a full-loop re-test that leakage is restored to within acceptable limits.

Test Points

Root Cause Verification

After repair, re-test the full loop and confirm leakage current is within the acceptable threshold, then monitor the trend over subsequent operating cycles.

Corrective Action

• Repair or replace the dominant contributing cable segment or joint.
• Replace the degrading transformer.
• Clean contaminated terminations.

Preventive Action

• Trend leakage current over time rather than relying on a single reading.
• Include termination cleaning in periodic PM.
• Calibrate monitoring equipment on a defined schedule.

Related References

SOP: SOP-CBL-06 (Leakage Current Investigation Procedure)

Standards: IEC 60364, ICAO Annex 14 Vol I

Diagram: Circuit route and transformer schedule

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Cable outer jacket/sheath along its buried or exposed route.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any repair involving cable handling.
• Confirm the circuit is de-energised even for jacket-only repairs, given the risk of undetected insulation compromise beneath.

Diagnostic Procedure

1. ObservationDocument the location, extent, and apparent cause of the jacket damage.
2. MeasurementMegger the cable at the damaged location to confirm whether the underlying insulation is still intact.
3. MeasurementAssess whether the damage is isolated or indicates a wider pattern, such as poor backfill practice along a run.
4. DecisionInsulation intact beneath the damage → jacket-only repair. Insulation compromised → treat as an insulation failure per CBL-345.
5. Fault LocationConfirm the extent of the damaged section requiring repair or replacement.
6. Root CauseConfirm the repaired section holds insulation resistance and jacket integrity.

Test Points

Root Cause Verification

Re-megger after repair and re-inspect the repaired section after backfilling to confirm jacket integrity is maintained.

Corrective Action

• Repair the jacket using an approved sleeve/wrap method matched to cable type, or replace the damaged section if repair is not viable.
• Correct the underlying cause, such as adding conduit protection or removing abrasive backfill.

Preventive Action

• Use proper bedding/backfill material and conduit protection during installation.
• Include jacket condition in periodic excavation-triggered inspections.
• Protect above-ground transitions from UV exposure.

Related References

SOP: SOP-CBL-07 (Jacket Damage Assessment and Repair Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Cable installation detail/bedding drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable conductor and insulation at the site of mechanical impact or deformation.

Possible Causes

Required Tools

Safety Precautions

• LOTO before handling.
• Treat any mechanically damaged section as a potential live hazard until isolation is confirmed.
• Use appropriate PPE for excavation work.

Diagnostic Procedure

1. ObservationDocument the nature and extent of the mechanical damage and the likely cause.
2. MeasurementMegger the cable to determine whether the damage has compromised insulation or conductor integrity.
3. MeasurementUse a TDR to confirm no additional damage exists further along the run from the same event.
4. DecisionLocalised damage with intact insulation → monitor or preemptively repair. Damage compromising insulation/conductor → full section replacement.
5. Fault LocationConfirm the full extent of the affected section.
6. Root CauseConfirm the repaired/replaced section meets insulation and continuity requirements.

Test Points

Root Cause Verification

After repair, re-test insulation resistance and continuity and re-inspect after backfilling to confirm no further deformation.

Corrective Action

• Replace the mechanically damaged cable section.
• Restore proper bedding/conduit protection.
• Splice using an approved method rated for the application.

Preventive Action

• Enforce utility locate and civil works coordination near buried circuits.
• Add mechanical protection (conduit, warning tape, marker) over vulnerable sections.
• Investigate ground movement risk in affected areas.

Related References

SOP: SOP-CBL-08 (Mechanical Damage Assessment Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Cable route and mechanical protection drawing

Case Study: Division 25 — Field Case Study Troubleshooting

Equipment / System

Cable cross-section at the crushed location, including conductor strands and surrounding insulation.

Possible Causes

Required Tools

Safety Precautions

• LOTO before handling.
• Assess whether the crushed section poses an immediate short/earth-fault hazard before any access.

Diagnostic Procedure

1. ObservationDocument the location and extent of crushing and identify the likely load source.
2. MeasurementMegger and continuity-test the crushed section to assess conductor and insulation condition.
3. MeasurementCheck conductor resistance against a known-good section of the same cable to detect strand damage even where insulation appears intact.
4. DecisionConductor/insulation compromised → replace the affected section. Conductor/insulation intact but crushed → monitor closely and consider preemptive replacement given fatigue risk.
5. Fault LocationConfirm the full extent of the crushed section.
6. Root CauseConfirm the replaced/repaired section meets specification.

Test Points

Root Cause Verification

After replacement, re-test insulation resistance and continuity, and confirm proper bedding/protection is restored before backfilling.

Corrective Action

• Replace the crushed cable section.
• Install conduit or additional mechanical protection at the location.
• Restore proper bedding.

Preventive Action

• Identify and protect known vehicle crossing points over buried circuits.
• Restrict unauthorised vehicle access over shallow cable routes.
• Use load-rated conduit at identified crossing points.

Related References

SOP: SOP-CBL-09 (Crushing Damage Repair Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Cable crossing protection drawing

Case Study: Division 25 — Field Case Study Troubleshooting

Equipment / System

Cable conductor and insulation at the cut location, and the affected series/secondary circuit as a whole.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any work at the cut location.
• Treat both ends of a cut cable as potentially live until isolation is confirmed at the source.
• Coordinate with the party responsible for the excavation to halt further work in the area.

Diagnostic Procedure

1. ObservationConfirm the timing and location of the fault against any known nearby excavation or ground-disturbing activity.
2. MeasurementUse TDR and cable locating equipment to confirm the exact location and extent of the cut.
3. MeasurementInspect both cut ends for the extent of conductor and insulation damage.
4. DecisionClean cut with minimal collateral damage → splice repair. Cut with extensive fraying/damage or contamination → replace the affected section.
5. Fault LocationConfirm the full extent of cable requiring repair or replacement.
6. Root CauseConfirm the splice/replacement restores full continuity and insulation resistance.

Test Points

Root Cause Verification

After repair, test the full loop for continuity and insulation resistance, re-energise, and confirm normal operation across an operating cycle.

Corrective Action

• Splice the cut cable using an approved kit rated for the cable type and burial environment, or replace the damaged section entirely.
• Update as-built drawings to reflect the repair location.

Preventive Action

• Enforce mandatory utility locate and permit-to-dig procedures for any excavation near AGL cable routes.
• Mark and maintain accurate cable route records.
• Consider additional route marking (tape, tracer wire) where not already present.

Related References

SOP: SOP-CBL-10 (Cable Cut Repair Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Cable route drawing with splice location log

Case Study: Division 24 — Complete Runway Lighting Failure

Equipment / System

Cable joints, pull boxes, base cans, and any point where the cable enters a below-grade enclosure.

Possible Causes

Required Tools

Safety Precautions

• LOTO before opening any enclosure suspected of water ingress.
• Treat submerged or wet components as live until insulation resistance is verified.
• Use appropriate PPE for confined space/wet conditions.

Diagnostic Procedure

1. ObservationInspect the affected enclosure at the next scheduled or triggered access for standing water or moisture.
2. MeasurementMegger the cable/joint before any re-energisation.
3. MeasurementInspect the joint kit, gland, lid seal, and drainage provision to identify the entry point.
4. DecisionInsulation resistance acceptable → dry out, reseal, and return to service. Insulation resistance degraded → treat as an insulation failure per CBL-345.
5. Fault LocationIsolate the specific seal, gland, lid, or drainage failure providing the entry point.
6. Root CauseConfirm the enclosure is fully dry and resealed before closing out.

Test Points

Root Cause Verification

After drying and resealing, re-megger, re-energise, and monitor through subsequent wet-weather cycles to confirm the entry point has been eliminated.

Corrective Action

• Replace the degraded joint kit or seal.
• Reseal the enclosure lid.
• Restore or improve the drainage provision.
• Repair a cracked enclosure.

Preventive Action

• Include enclosure seal and drainage inspection in the periodic PM cycle.
• Use joint kits and gland seals rated for continuous submersion where groundwater is a known risk.
• Improve site drainage around affected enclosures.

Related References

SOP: SOP-CBL-11 (Enclosure Moisture Inspection Procedure)

Standards: FAA AC 150/5340-30, IEC 60364

Diagram: Joint pit and base can drainage detail drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable insulation and conductor system along its buried length, distinct from joint/enclosure water ingress.

Possible Causes

Required Tools

Safety Precautions

• LOTO before testing.
• Treat a 'wet' diagnostic result as indicating a developing insulation hazard.

Diagnostic Procedure

1. ObservationReview the insulation resistance trend over time for a gradual decline consistent with moisture migration rather than a sudden step-change.
2. MeasurementWhere available, perform a dielectric diagnostic test (tan-delta/VLF) to characterise the moisture condition of the insulation.
3. MeasurementInspect cable ends and any accessible jacket sections for a moisture entry point.
4. DecisionMoisture confirmed and localised to an entry point → repair/reterminate. Moisture distributed along an aged cable design → plan proactive replacement.
5. Fault LocationIsolate to the entry point where identifiable, or characterise as a whole-cable condition.
6. Root CauseConfirm improvement in diagnostic results after any repair.

Test Points

Root Cause Verification

Retest insulation resistance and, where available, the dielectric diagnostic after repair, and continue trending to confirm the condition has stabilised or improved.

Corrective Action

• Reterminate/reseal a failed end-seal.
• Replace the affected cable section where moisture is confirmed to have significantly degraded the insulation.
• Replace with a moisture-rated cable design for permanently wet environments.

Preventive Action

• Specify moisture-rated/water-blocked cable for known high-water-table or wet environments.
• Properly seal cable ends during storage and before termination.
• Include periodic dielectric diagnostic testing for critical, older circuits.

Related References

SOP: SOP-CBL-12 (Cable Moisture Diagnostic Procedure)

Standards: IEC 60502/60840 (cable testing reference), IEEE 400 (VLF diagnostic guidance), FAA AC 150/5340-30

Diagram: Cable specification and installation record

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable joint/splice kit and its enclosure, at any point along the primary or secondary circuit.

Possible Causes

Required Tools

Safety Precautions

• LOTO before opening a suspect joint.
• Treat a joint showing thermal damage as a potential fire/arc hazard.

Diagnostic Procedure

1. ObservationIdentify the specific joint from the circuit fault characteristics (open, short, or earth fault) and the route drawing.
2. MeasurementWith the circuit isolated, inspect the joint for visible damage, discolouration, or water presence.
3. MeasurementMegger and continuity-test across the joint to confirm the failure mode.
4. DecisionJoint kit installation/workmanship deficiency → remake the joint per approved procedure. Joint kit type mismatch → replace with the correctly specified kit.
5. Fault LocationConfirm the joint is the sole point of failure and not indicative of a wider section issue.
6. Root CauseConfirm the remade joint meets insulation and continuity requirements.

Test Points

Root Cause Verification

After remaking the joint, test continuity and insulation resistance, re-energise, and thermal-image the joint under normal load to confirm no abnormal heating.

Corrective Action

• Remake the joint using an approved kit and procedure matched to the cable type and environment.
• Replace the joint enclosure if damaged.

Preventive Action

• Standardise on qualified joint kits and installer training/certification.
• Include joint inspection in the periodic PM cycle, particularly for older or high-fault-history joints.
• Maintain a joint location log for the circuit.

Related References

SOP: SOP-CBL-13 (Cable Jointing Procedure)

Standards: IEC 60502, FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Joint location log and circuit route drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable joint/splice connection point, specifically the conductor-to-conductor crimp or connector interface within the joint.

Possible Causes

Required Tools

Safety Precautions

• LOTO before opening the joint.
• A high-resistance joint may be hot to the touch even after isolation — allow time to cool before handling.

Diagnostic Procedure

1. ObservationIdentify the symptom (flicker, dimming, downstream voltage drop) and correlate it with a specific joint location using the circuit route.
2. MeasurementThermal image the joint under normal load to confirm a hot-spot signature.
3. MeasurementWith the circuit isolated, measure the joint's resistance directly using a micro-ohmmeter and compare against an acceptable threshold.
4. DecisionResistance confirmed elevated → remake the joint. Thermal/resistance readings normal → investigate other causes downstream.
5. Fault LocationConfirm the specific joint is the source rather than an adjacent connection.
6. Root CauseConfirm resistance is restored to an acceptable value after remake.

Test Points

Root Cause Verification

After remaking the joint, re-measure resistance, re-energise, and thermal-image under normal load to confirm the hot spot has been eliminated.

Corrective Action

• Remake the joint with a properly cleaned, correctly sized, and properly crimped/torqued connector.
• Replace a corroded or galvanically incompatible connector.

Preventive Action

• Include thermal imaging of accessible joints in the periodic PM cycle.
• Use connectors rated to prevent galvanic corrosion between dissimilar metals.
• Verify crimp/torque specification is followed at every jointing.

Related References

SOP: SOP-CBL-14 (High Resistance Joint Detection Procedure)

Standards: IEC 60502, FAA AC 150/5340-30

Diagram: Joint location log and circuit route drawing

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

Cable joint/splice connector and its enclosure.

Possible Causes

Required Tools

Safety Precautions

• LOTO before opening the joint.
• Secure/support the cable before disturbing a loose connector to avoid further movement.

Diagnostic Procedure

1. ObservationIdentify the loose joint during a routine inspection or as follow-up to a flagged high-resistance/flicker symptom.
2. MeasurementThermal image the joint under load to check for a developing hot spot.
3. MeasurementMeasure joint resistance to confirm whether looseness has yet caused electrical degradation.
4. DecisionResistance still normal → retighten/recrimp as a preventive action. Resistance already elevated → treat as CBL-355 (high resistance joint) and remake fully.
5. Fault LocationConfirm the specific joint and connector type.
6. Root CauseConfirm secure mechanical connection and normal resistance after correction.

Test Points

Root Cause Verification

Re-check the joint after a subsequent PM cycle to confirm it has not worked loose again.

Corrective Action

• Retighten or recrimp the connector to specification.
• Replace an unsuitable connector type.
• Improve enclosure support to reduce movement.

Preventive Action

• Verify torque/crimp specification at every jointing.
• Include a physical security check of accessible joints in periodic PM.
• Use vibration-resistant connectors in high-traffic areas.

Related References

SOP: SOP-CBL-13 (Cable Jointing Procedure), SOP-CBL-14 (High Resistance Joint Detection Procedure)

Standards: IEC 60502, FAA AC 150/5340-30

Diagram: Joint location log and circuit route drawing

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

Cable joint/splice kit and installation method used at a specific location.

Possible Causes

Required Tools

Safety Precautions

• LOTO before remaking a suspect joint.
• Treat any joint of unknown provenance as a potential hazard until verified.

Diagnostic Procedure

1. ObservationIdentify the joint from a failed test result, a visible non-standard method, or a maintenance record review.
2. MeasurementMegger and continuity-test the joint to assess its current condition.
3. MeasurementCompare the joint construction against the approved procedure/kit specification.
4. DecisionJoint condition acceptable but method non-compliant → schedule remake at next opportunity. Joint already degraded → remake immediately per CBL-354.
5. Fault LocationConfirm the joint and document the non-compliance found.
6. Root CauseConfirm the remade joint meets specification and testing requirements.

Test Points

Root Cause Verification

After remaking, test and document compliance with the approved procedure, and retain records for the circuit's joint log.

Corrective Action

• Remake the joint using an approved kit and procedure.
• Retrain or reassign the installer if a workmanship pattern is identified.

Preventive Action

• Require installer certification for cable jointing.
• Conduct post-installation insulation resistance testing before backfilling as a standard step.
• Audit joint records periodically.

Related References

SOP: SOP-CBL-13 (Cable Jointing Procedure)

Standards: IEC 60502, FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Joint kit specification and approved method reference

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable route as installed, evaluated against the as-built drawing and applicable clearance/protection standards.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any excavation to verify routing.
• Coordinate with other utility owners if a clearance conflict is suspected.

Diagnostic Procedure

1. ObservationIdentify the discrepancy between the as-built drawing and the field-verified route, typically triggered by an excavation, fault investigation, or audit.
2. MeasurementTrace and survey the actual cable route using locating equipment.
3. MeasurementCheck clearance from other buried services and from vehicle-loading areas against the applicable standard.
4. DecisionDeviation is documented and within acceptable clearance → update the as-built drawing only. Deviation creates a clearance or protection risk → plan a reroute or add protection.
5. Fault LocationConfirm the extent of the affected route section.
6. Root CauseConfirm the corrected route or updated documentation resolves the discrepancy.

Test Points

Root Cause Verification

After correction, re-survey and confirm the route matches the updated as-built drawing, and archive the survey record.

Corrective Action

• Update the as-built drawing to reflect the verified route where acceptable.
• Reroute or add protection where a clearance/risk issue is confirmed.

Preventive Action

• Enforce as-built drawing updates as a mandatory close-out step for any cable work.
• Conduct periodic route audits against records.
• Coordinate with other utility owners before new installations near AGL cable routes.

Related References

SOP: SOP-CBL-15 (Cable Route Verification Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Cable as-built route drawing

Case Study: Division 25 — Field Case Study Troubleshooting

Equipment / System

Cable at a bend point, particularly at transitions into base cans, pull boxes, conduit entries, or direction changes in the trench.

Possible Causes

Required Tools

Safety Precautions

• LOTO before handling the cable.
• Do not attempt to straighten a tightly bent cable while energised.

Diagnostic Procedure

1. ObservationIdentify the bend point and estimate the radius against the cable manufacturer's minimum specification.
2. MeasurementMegger the cable at and adjacent to the bend to check for insulation stress damage.
3. MeasurementInspect the jacket at the bend for cracking or crazing.
4. DecisionBend within tolerance and no damage found → no action required beyond noting for future reference. Bend exceeds tolerance or damage present → re-route with adequate radius or replace the affected section.
5. Fault LocationConfirm the extent of any damage caused by the excessive bend.
6. Root CauseConfirm insulation resistance is acceptable after correction.

Test Points

Root Cause Verification

After correction, re-megger and re-inspect the corrected section, and confirm adequate slack/radius before backfilling.

Corrective Action

• Re-route the cable to achieve the minimum bend radius.
• Install a larger-radius conduit sweep or base can entry fitting.
• Replace a damaged section.

Preventive Action

• Specify minimum bend radius requirements in installation procedures and inspect during construction.
• Provide adequate slack at joints, terminations, and direction changes.
• Train installers on proper handling and storage of cable reels.

Related References

SOP: SOP-CBL-16 (Cable Handling and Installation Procedure)

Standards: Cable manufacturer installation specification, ICAO Annex 14 Vol I

Diagram: Cable installation detail/bedding drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable conductor and insulation system along a specific section, evaluated for excess heating relative to its rated ampacity and installation conditions.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any hands-on work at an overheating section.
• Allow time to cool before handling.
• Treat sustained overheating as a fire/insulation-failure risk.

Diagnostic Procedure

1. ObservationConfirm the overheating via thermal imaging or alarm history and correlate with load conditions at the time.
2. MeasurementMeasure actual circuit current and compare against the cable's rated ampacity for its installation method.
3. MeasurementInspect the section for a high-resistance joint or connection contributing localised heat.
4. DecisionOverheating due to a specific joint → remake the joint per CBL-355. Overheating due to genuine overload/undersizing → investigate cable sizing per CBL-363.
5. Fault LocationIsolate to the specific joint, connection, or a distributed sizing/installation issue.
6. Root CauseConfirm temperature returns to the normal range after correction.

Test Points

Root Cause Verification

Monitor the section's temperature trend over subsequent operating cycles, including peak load conditions, to confirm the overheating has been resolved.

Corrective Action

• Remake a high-resistance joint.
• Upsize or replace an undersized cable section.
• Improve bedding/thermal dissipation.
• Correct conduit fill or spacing.

Preventive Action

• Verify cable sizing against actual and projected load at the design stage and after any circuit modification.
• Include thermal imaging of accessible sections and joints in periodic PM.

Related References

SOP: SOP-CBL-17 (Cable Thermal Assessment Procedure)

Standards: IEC 60287 (cable current rating), FAA AC 150/5340-30

Diagram: Cable ampacity/derating reference and circuit loading record

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

Cable conductor resistance across its full run length, evaluated for cumulative voltage drop under the circuit's operating current.

Possible Causes

Required Tools

Safety Precautions

• LOTO before hands-on measurement at multiple points along the run.
• Coordinate airside access for measurement points along the circuit.

Diagnostic Procedure

1. ObservationMeasure voltage at the source and at the affected point(s) under normal operating current to quantify the drop.
2. MeasurementCalculate the expected voltage drop for the cable size, length, and current, and compare to the measured value.
3. MeasurementCheck for a high-resistance joint contributing an unexpected additional drop.
4. DecisionMeasured drop consistent with cable size/length → undersized/over-length cable, plan upsizing or a booster/relocated feed point. Measured drop exceeds calculation → investigate a specific joint or degraded section.
5. Fault LocationIsolate to a distributed sizing issue or a specific high-resistance point.
6. Root CauseConfirm voltage at the affected point is restored to an acceptable range after correction.

Test Points

Root Cause Verification

Re-measure voltage at the affected point after correction under normal operating load and confirm it falls within the acceptable range.

Corrective Action

• Remake an identified high-resistance joint.
• Upsize the conductor for the affected run.
• Relocate the feed point or add a parallel feed where a full resize is impractical.

Preventive Action

• Verify voltage drop calculations at the design stage for all run lengths, including future extensions.
• Include voltage measurement at end-of-run points in periodic PM for long circuits.

Related References

SOP: SOP-CBL-18 (Voltage Drop Assessment Procedure)

Standards: IEC 60364, FAA AC 150/5340-30

Diagram: Circuit voltage drop calculation record

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Cable run length as installed, evaluated against the design specification and as-built record.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any verification work requiring cable access.

Diagnostic Procedure

1. ObservationIdentify the discrepancy, typically via a voltage drop calculation mismatch, insufficient slack, or a route audit finding.
2. MeasurementUse TDR or physical survey to determine the actual installed cable length.
3. MeasurementCompare against the design specification and as-built record.
4. DecisionDiscrepancy is a documentation error only, with no operational impact → update as-built records. Discrepancy is causing a voltage drop or slack problem → proceed to the relevant corrective action.
5. Fault LocationConfirm the specific run affected.
6. Root CauseConfirm updated records and, where applicable, corrected physical condition.

Test Points

Root Cause Verification

After correction, confirm the as-built record matches the field-verified length and that any downstream voltage drop or slack issue has been resolved.

Corrective Action

• Update as-built documentation to reflect the verified length.
• Add or reroute cable where insufficient length is causing an operational issue.
• Trim and re-terminate where excess length is causing installation difficulty.

Preventive Action

• Verify cut lengths against the route survey before installation.
• Update as-built records at project close-out and after any subsequent repair.
• Include length verification in periodic route audits.

Related References

SOP: SOP-CBL-15 (Cable Route Verification Procedure)

Standards: FAA AC 150/5340-30

Diagram: Cable as-built route and length record

Case Study: Division 25 — Field Case Study Troubleshooting

Equipment / System

Cable conductor size as installed, evaluated against the circuit's design specification.

Possible Causes

Required Tools

Safety Precautions

• LOTO before physical verification of cable size at an accessible point.

Diagnostic Procedure

1. ObservationIdentify the discrepancy via a voltage drop, overheating, or documentation review finding.
2. MeasurementVerify the actual installed cable size at an accessible point using markings, caliper measurement, or cut-end inspection.
3. MeasurementCompare against the design specification and recalculate ampacity/voltage drop for the actual size and run conditions.
4. DecisionUndersized cable causing a measurable operational issue → plan replacement with correctly sized cable. Size discrepancy without a measurable operational issue → update records and monitor.
5. Fault LocationConfirm the extent of the run affected by the incorrect size.
6. Root CauseConfirm the replaced section meets the design specification and operates within acceptable limits.

Test Points

Root Cause Verification

After replacement, re-verify cable size and re-measure voltage/current at the affected point to confirm compliance.

Corrective Action

• Replace the incorrectly sized cable section with the correctly specified size.
• Update design/as-built documentation.

Preventive Action

• Verify cable size against the design specification before installation.
• Implement clear reel labelling and stock control to prevent size mix-ups.
• Re-evaluate cable sizing whenever a circuit is extended or its load changes.

Related References

SOP: SOP-CBL-19 (Cable Size Verification Procedure)

Standards: IEC 60364, IEC 60287, FAA AC 150/5340-30

Diagram: Circuit design specification and cable schedule

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Cable identification tags/markers at pull boxes, base cans, and panel terminations, and the associated as-built/circuit schedule documentation.

Possible Causes

Required Tools

Safety Precautions

• LOTO based on verified identification only, never on a tag alone.
• Always confirm isolation electrically before work, since incorrect identification is a direct safety hazard.

Diagnostic Procedure

1. ObservationIdentify the discrepancy, typically when a tag does not match the expected circuit during maintenance or fault-finding.
2. MeasurementUse tone-and-trace equipment to positively identify the cable's actual circuit and destination.
3. MeasurementCross-reference the traced result against the as-built drawing and circuit schedule.
4. DecisionTag is simply incorrect/missing with no wider documentation issue → correct the tag. Discrepancy indicates a wider as-built/schedule error → update the drawing and audit related cables in the same area.
5. Fault LocationConfirm the specific cable(s) affected.
6. Root CauseConfirm corrected identification matches the verified circuit.

Test Points

Root Cause Verification

After correction, re-verify the tag against a tone-and-trace check, and confirm the as-built documentation is updated and consistent.

Corrective Action

• Apply correct, durable identification tags/markers.
• Update the as-built drawing and circuit schedule.

Preventive Action

• Use durable, standardised tagging at every joint, pull box, and termination.
• Verify and update identification as a mandatory step after any rerouting or repair.
• Conduct periodic identification audits.

Related References

SOP: SOP-CBL-20 (Cable Identification and Tracing Procedure)

Standards: FAA AC 150/5340-30, site electrical safety procedure

Diagram: Circuit schedule and identification tagging standard

Case Study: Division 24 — Complete Runway Lighting Failure

Equipment / System

Cable conductor termination at a connector, transformer, or panel, where polarity or phase sequence must be correctly maintained.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any termination work.
• Verify de-energisation with a meter even where a circuit is believed isolated, given the risk of incorrect labelling contributing to the original error.

Diagnostic Procedure

1. ObservationIdentify the abnormal behaviour and correlate it with a specific cable, connector, or termination suspected of a polarity/phase error.
2. MeasurementVerify polarity or phase sequence at the suspect termination using a meter with the circuit isolated and appropriately tested.
3. MeasurementTrace the conductor from source to load to confirm correct connection at each point.
4. DecisionError confirmed at a specific termination → correct the connection. Error not found at the suspect point → continue tracing further along the circuit.
5. Fault LocationIsolate to the specific termination or cable section with the error.
6. Root CauseConfirm correct polarity/phase after correction.

Test Points

Root Cause Verification

After correction, re-verify polarity/phase, re-energise, and confirm the fixture(s) or downstream equipment operate correctly.

Corrective Action

• Correct the conductor connection at the identified termination.
• Re-mark conductors clearly where colour coding was ambiguous or missing.

Preventive Action

• Enforce verification of polarity/phase as a mandatory step after any termination or reconnection work.
• Maintain clear and consistent conductor marking standards.
• Use phase rotation meters as a standard check on multi-phase feeder work.

Related References

SOP: SOP-CBL-21 (Polarity and Phase Verification Procedure)

Standards: IEC 60364, FAA AC 150/5340-30

Diagram: Circuit wiring diagram with conductor marking standard

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Cable conductor and insulation at the location affected by the civil works activity, and the associated circuit as a whole.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any investigation or repair.
• Coordinate with the civil works contractor to halt activity in the affected area until the extent of damage is established.

Diagnostic Procedure

1. ObservationCorrelate the fault timing and location with known civil works activity in the area.
2. MeasurementUse TDR and locate equipment to confirm the exact location and nature of the damage.
3. MeasurementReview the utility locate records and works permit to establish whether proper procedure was followed.
4. DecisionDamage confirmed at a specific point → proceed with repair per the applicable fault type. Root cause is a process failure → escalate for coordination review in addition to the physical repair.
5. Fault LocationConfirm the full extent of cable affected by the civil works activity.
6. Root CauseConfirm repair restores full circuit integrity and document the incident for the coordination record.

Test Points

Root Cause Verification

After repair, test the full loop for continuity and insulation resistance, re-energise, and confirm normal operation; log the incident against the works coordination process.

Corrective Action

• Repair or replace the damaged cable section using the procedure appropriate to the fault type found.
• Update as-built records to reflect the repair.

Preventive Action

• Enforce mandatory utility locate and permit-to-dig procedures for all civil works near AGL cable routes.
• Require pre-works briefings referencing as-built drawings for any contractor working near known cable corridors.
• Consider additional protective marking in areas with frequent civil works activity.

Related References

SOP: SOP-CBL-10 (Cable Cut Repair Procedure), SOP-CBL-22 (Civil Works Coordination Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Cable route drawing with civil works coordination log

Case Study: Division 24 — Complete Runway Lighting Failure

Equipment / System

Cable insulation system and joints/enclosures at points vulnerable to rainwater ingress along the affected circuit.

Possible Causes

Required Tools

Safety Precautions

• LOTO before testing.
• Treat a rain-triggered fault as indicating a real, if intermittent, hazard rather than a nuisance condition.

Diagnostic Procedure

1. ObservationConfirm the fault onset correlates with a specific rainfall event using CCR trip logs and weather records.
2. MeasurementMegger the circuit in segments to localise the section most affected.
3. MeasurementInspect the identified segment's joints, pull boxes, and enclosures for a moisture entry point once accessible.
4. DecisionMoisture entry point identified and localised → repair per CBL-352 (water ingress) or CBL-353 (moisture ingress) as appropriate. Fault clears on its own with no identifiable entry point → monitor closely and re-test after the next rain event.
5. Fault LocationIsolate to the specific segment, joint, or enclosure responsible.
6. Root CauseConfirm the fault does not recur after a subsequent rainfall event of similar or greater intensity.

Test Points

Root Cause Verification

After repair, monitor the circuit through at least one subsequent significant rainfall event and confirm the insulation resistance remains stable.

Corrective Action

• Reseal or repair the identified moisture entry point.
• Repair or replace a degraded cable/jacket section that only fails under wet conditions.

Preventive Action

• Correlate periodic insulation resistance testing with weather conditions to catch rain-sensitive defects proactively.
• Prioritise seal and drainage inspection ahead of the wet season.
• Trend circuits with a history of rain-related faults for closer monitoring.

Related References

SOP: SOP-CBL-11 (Enclosure Moisture Inspection Procedure), SOP-CBL-04 (Earth Fault Location Procedure)

Standards: IEC 60364, FAA AC 150/5340-30

Diagram: Circuit route drawing with joint/enclosure locations

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

Cable, joints, pull boxes, base cans, and CCR/transformer enclosures within the flooded area.

Possible Causes

Required Tools

Safety Precautions

• LOTO all affected circuits before any inspection.
• Treat all submerged equipment as unsafe to energise until fully assessed.
• Be alert to additional hazards — silt, debris, wildlife — in flood-affected enclosures.

Diagnostic Procedure

1. ObservationIdentify and map the full extent of the flooded area and all potentially affected enclosures and cable sections.
2. MeasurementMegger every affected segment and piece of equipment before considering re-energisation, prioritising the most critical circuits.
3. MeasurementInspect for contamination (silt, chemical residue, saltwater) in addition to simple moisture.
4. DecisionInsulation resistance acceptable after thorough drying → return to service with continued monitoring. Insulation resistance remains degraded or contamination is present → treat as insulation failure per CBL-345 and plan targeted or wholesale replacement.
5. Fault LocationMap the full extent of flood-affected cable and equipment requiring assessment.
6. Root CauseConfirm every affected component is individually verified before restoring the circuit.

Test Points

Root Cause Verification

After drying, cleaning, and repair, re-megger all affected sections, re-energise progressively, and monitor closely over the following days for any delayed degradation.

Corrective Action

• Thoroughly dry and clean all affected joints, enclosures, and equipment.
• Replace cable sections and components where contamination or submersion has exceeded their rating.
• Reseal and restore all affected enclosures.

Preventive Action

• Review drainage and flood risk for low-lying enclosures and circuits.
• Consider upgrading ingress protection ratings for equipment in known flood-prone areas.
• Develop a flood response procedure prioritising critical circuit assessment.

Related References

SOP: SOP-CBL-23 (Flood Response and Assessment Procedure), SOP-CBL-11 (Enclosure Moisture Inspection Procedure)

Standards: IEC 60364, FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Site drainage and flood risk map

Case Study: Division 24 — Complete Runway Lighting Failure

Equipment / System

The specific cable section, joint, or circuit with a documented history of repeat faults, and the repair method(s) previously applied.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any investigation.
• Treat a location with a repeat-fault history with heightened caution given the demonstrated pattern of failure.

Diagnostic Procedure

1. ObservationCompile the full fault history for the location, including dates, fault types, and repair methods previously used.
2. MeasurementRe-test the current condition of the repaired section and surrounding area to establish the present state.
3. MeasurementInvestigate site-specific conditions — traffic loading, groundwater, ground movement — that may be a recurring contributing factor rather than the cable/joint itself.
4. DecisionPattern points to an inadequate repair method → upgrade to a more robust repair/protection approach. Pattern points to a persistent site condition → address the underlying condition in addition to the cable repair.
5. Fault LocationConfirm whether the repeat faults are genuinely at the same point or several distinct nearby points.
6. Root CauseConfirm the underlying cause, not just the immediate fault, has been addressed.

Test Points

Root Cause Verification

Monitor the location over an extended period, and multiple wet/dry and loading cycles, to confirm the fault does not recur following the upgraded repair.

Corrective Action

• Upgrade the repair method — a more robust joint kit, additional mechanical protection, or rerouting away from a damaging condition.
• Address the underlying site condition contributing to repeat failure.

Preventive Action

• Maintain a fault history log by location to identify repeat-fault patterns early.
• Escalate repeat faults at the same location for root cause analysis rather than routine repair after the second occurrence.
• Review repair standards where a pattern of inadequate repairs is identified.

Related References

SOP: SOP-CBL-24 (Repeat Fault Root Cause Analysis Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Circuit fault history log and route drawing

Case Study: Division 25 — Field Case Study Troubleshooting

Equipment / System

The complete buried cable route for the affected circuit, evaluated using non-invasive fault-location techniques before physical excavation.

Possible Causes

Required Tools

Safety Precautions

• LOTO before any fault-location testing.
• Coordinate airside/pavement access before any excavation is planned.
• Ensure any surge/thumper testing is performed by qualified personnel given the higher test voltages involved.

Diagnostic Procedure

1. ObservationConfirm the fault type (open, short, earth fault) and general section of the circuit via segment testing from accessible points.
2. MeasurementUse TDR to obtain an initial distance-to-fault estimate from the nearest accessible point in each direction.
3. MeasurementApply a secondary locating method, such as surge/thumper with acoustic/electromagnetic tracing or ARC reflection, to pinpoint the fault location on the surface.
4. DecisionFault location narrowed to a confident pinpoint → proceed with minimal, targeted excavation. Location remains uncertain after available methods → consider a wider excavation window or engage specialist fault-location services.
5. Fault LocationConfirm the pinpointed location before committing to excavation, particularly under pavement.
6. Root CauseConfirm the fault is fully resolved once excavated and repaired, and that the electrical signature matches expectations.

Test Points

Root Cause Verification

After excavation and repair, test the full loop for continuity and insulation resistance, and confirm the excavated location matches the electrical signature that was present before repair.

Corrective Action

• Excavate at the pinpointed location and repair per the applicable fault type.
• Minimise excavation extent, particularly under pavement, through accurate pinpointing.

Preventive Action

• Maintain accurate, updated as-built route drawings to support future fault location.
• Consider installing tracer wire or route markers on new/replacement cable runs to aid future location.
• Invest in or retain access to specialist fault-location equipment/services for circuits without ready pull-box access.

Related References

SOP: SOP-CBL-01 (Primary Series Circuit Fault Location Procedure), SOP-CBL-25 (Precision Fault Location Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Circuit route drawing with fault-location survey markers

Case Study: Division 25 — Field Case Study Troubleshooting