What is FAA L-824 Type C 5kV Airport Lighting Cable?

• Continuous operation in series lighting circuits
• Exposure to moisture, de-icing chemicals, fuel, and oils
• Direct burial in soil, ducts, and conduits
• Long runs under large paved areas with minimal maintenance access

• FAA – primarily FAA Advisory Circular AC 150/5345-7 and L-824 specifications
• ICAO – Annex 14 and related guidance
• ICEA / IEC – for insulation, construction, and performance criteria

Airport Lighting Cable Types and Circuit Basics

Primary vs. Secondary Lighting Circuits

• Primary circuits (medium-voltage series circuits)
  • Operate typically at up to 5kV
  • Connect the constant current regulator (CCR) in the electrical vault to numerous isolation transformers installed near each fixture
  • Common conductor sizes are 8, 6 and 4 AWG
• Secondary circuits (low-voltage lamp leads)
  • Operate at low voltage (600V) on the secondary side of each isolation transformer.
  • Use short lengths of flexible cable from the transformer to the individual lamp or LED fixture.
  • Generally 10 or 12 AWG conductor sizes

Constant Current Regulators and Series Circuits

• A constant current regulator (CCR) that maintains a specified current (often 6.6 A) through the circuit.
• A series loop of cable with multiple isolation transformers inserted in line.
• Lamps or LED fixtures connected to the transformer secondary.

Common Voltage Ratings and FAA L-824 Types

• 600V – for low-voltage applications in secondary circuits (lighting and control)
• 2kV – used in some primary AGL designs
• 5kV – standard rating for many primary series circuits

• Type A – An older design standard that is not as well specified as B or C
• Type B – Single-conductor primary cable, often used for long single-core runs.
• Type C – Multi-conductor primary cable, available in both 600 V and 5 kV versions.

What Is FAA L-824 Type C 5kV Airport Lighting Cable?

• Function: Primary circuit cable carrying 5 kV class voltage between CCRs and isolation transformers.
• Construction: Multiple insulated conductors under a common jacket or common assembly, sized and spaced according to L‑824 dimensional tolerances.
• Application: Runway and taxiway edge lighting, centerline lighting, approach lighting systems, and other series circuits where several conductors are needed in a single cable.

Role in Primary Series Circuits

1. The CCR sends constant current into the primary loop.
2. The current flows through FAA L‑824 Type B or Type C 5kV cable.
3. Isolation transformers are spliced into the loop at regular intervals.
4. Each transformer feeds one or more fixtures on its low-voltage secondary.

• Multiple circuits installed in a common trench or duct
• Circuits feeding several CCRs in the same route
• Configurations that benefit from reduced installation time and fewer individual pulls

Typical Use Cases

• Runway lighting: Feeding multiple series circuits for runway edge lights, centerline lights, and touchdown zone lights along a single corridor.
• Taxiway lighting: Routing parallel series circuits for taxiway edge and centerline lights where space is limited.
• Approach lighting systems (ALS): Supporting multiple high-intensity approach circuits from a central vault to the approach end of the runway.

How Type C 5kV Differs from Type B and 600 V Type C

• Versus Type B
  • Type B is single-conductor, 5 kV primary cable.
  • Type C 5kV is multi-conductor, allowing several primary conductors in one cable assembly.
• Versus 600 V Type C
  • Type C 600 V constructions serve lower-voltage applications and are not equivalent to 5 kV primary cable.
  • Type C 5kV has a thicker insulation system, higher dielectric strength, and stricter dimensional constraints to meet 5 kV performance.

FAA L-824 Type C 5kV Construction and Materials

Conductor

• Material: Soft annealed copper
• Form: Stranded (often 7-strand) for flexibility and consistent diameter
• Sizes: Commonly AWG 8, AWG 6, and AWG 4 for primary circuits

Insulation System

• Conductor shield:
  • An extruded semi-conducting layer over the copper conductor to control electric field stress and reduce partial discharge risk.
• Primary insulation:
  • Cross-linked polyethylene (XLPE) or occasionally EPR (Ethylene Propylene Rubber), formulated for:
    • Medium-voltage dielectric performance
    • Heat resistance at 90°C normal operating temperature
    • Track resistance to surface discharges
• Insulation thickness:
  • Typically around 110 mils (0.110 in) for 5 kV designs complying with L‑824 and ICEA standards.

Shielding and Sheathing Options

• Unshielded – Individual insulated conductors with no metallic shield, used where earth return and induced voltages are controlled by layout and system design.
• Shielded – Each conductor includes a metallic shield (e.g., copper tape, copper wire braid) to control electric fields and reduce interference or touch potential.
• Sheathed – Conductors assembled under a common outer jacket (e.g., PVC or PE) to create a compact multi-core cable.

• Local soil conditions
• Interference concerns
• Mechanical protection needs
• Airport engineering specifications

Temperature Ratings

• 90°C – Normal operation
• 130°C – Emergency overload conditions
• 250°C – Short-circuit conditions (for limited duration)

Example Construction Data (Representative Values)

Key Technical Characteristics of FAA L-824 Type C 5kV Cable

Electrical Characteristics

• Voltage rating:
  • 5,000 V (5 kV) phase-to-ground, suitable for AGL series circuits driven by CCRs.
• Dielectric performance:
  • XLPE or EPR insulation plus semi-conducting shields designed to withstand long-term electrical stress and switching transients.
• Capacitance and charging current:
  • Managed through careful design of insulation thickness and conductor spacing so that series circuits remain stable over long distances.
• Corona and partial discharge resistance:
  • Semi-conducting shields and high-quality extrusion reduce partial discharge, extending service life.

Mechanical Characteristics

• Flexibility:
  • Stranded copper conductors and cross-linked insulation provide enough flexibility for installation in ducts and trenches while maintaining dimensional stability.
• Abrasion resistance:
  • XLPE insulation and any outer jackets are formulated to resist damage during pulling, backfilling, or movement in conduits.
• Tensile strength:
  • Cable core and jackets are designed to tolerate installation tension within specified limits without conductor or insulation damage.

Environmental Performance

• Moisture and standing water in ducts and pits
• De-icing fluids, fuels, oils, and cleaning chemicals
• Soil with variable pH and contaminants
• Temperature swings, including freeze–thaw cycles

• Continuous wet or dry operation at 90°C
• Direct burial without metallic armor, relying on robust polymer jackets for protection
• Long-term exposure to common chemicals encountered around aprons and runways

Service Life Considerations

• Quality of splices and terminations
• Protection against water ingress at joints and connectors
• Avoidance of mechanical damage or over-tension during installation
• Effective lightning and surge protection on CCRs and circuits

Primary Circuit Application: Where FAA L-824 Type C 5kV Is Used

Connection Between CCR and Isolation Transformers

• FAA L‑824 Type C 5kV cable leaves the CCR in the vault.
• The cable runs through duct banks, trenches, or direct burial paths toward the runway or taxiway.
• At each fixture location, the cable is spliced to insert an isolation transformer into the loop.
• The loop returns to the CCR to complete the series circuit.

Layout in Runway and Taxiway Circuits

• Single-run circuits: One series loop served by a Type B or single-circuit Type C cable.
• Multi-circuit corridors: Several series circuits (e.g., approach, edge, and centerline) bundled in one multi-core Type C 5kV cable running along the same physical route.
• Branch circuits: Multi-core Type C cable feeding different legs of a lighting system where multiple CCRs or different intensity systems share common paths.

Distinction from Secondary Lamp Leads and Control Wiring

• Secondary lamp leads – low-voltage, highly flexible cable from isolation transformers to fixtures. These are not 5 kV primary cables.
• Control and monitoring cables – low-voltage multi-core or fiber cables used for lighting control systems, monitoring, or communication.

Typical Installation Environments

• Direct burial in trenches, often with sand bedding and marking tape
• Installation in PVC or HDPE ducts, especially under pavements and in congested corridors
• Manholes and handholes, where splices and transformers are accessed
• Limited aerial spans, where allowable by design and local regulations

How FAA L-824 Type C 5kV Differs from Other Airport Cables

Comparison with FAA L-824 Type B 5 kV Single-Core Cables

• Single conductor only
• Often used where each series circuit has its own dedicated cable run
• Simplifies fault location per circuit but requires more individual cable pulls

• Multiple conductors in one assembly
• Allows multiple circuits along a shared route
• Reduces installation time and duct occupancy, but calls for careful identification and separation of conductors by circuit

Comparison with 600 V FAA L-824 Type C Cables

• Intended for lower-voltage applications
• Have thinner insulation and different test requirements
• May be multi-core and used for control or lower-voltage lighting arrangements

• Specifically designed for primary 5 kV series circuits
• Uses a higher-grade insulation system and thicker insulation
• Must not be downgraded to “secondary low-voltage” cable in design assumptions

Differences from Standard Medium-Voltage Power Cable

• Dimensional tolerances: FAA L‑824 controls OD and tolerances to ensure compatibility with airfield connectors, splices, and fittings.
• Series circuit focus: Designed for constant-current series operation rather than conventional radial feeders.
• Application-specific testing: Manufactured and tested with airfield environments and FAA criteria in mind.

Common Terminology in Airport Lighting Cable

• AGL (Airfield Ground Lighting) – The complete system of in-pavement and elevated lights, cables, regulators, and controls.
• CCR (Constant Current Regulator) – Power supply that maintains stable current through the primary loop.
• Isolation transformer – Device inserted into the series loop to isolate the fixture and allow lamp replacement without breaking the loop.
• Primary circuit – High-voltage series loop between the CCR and the primary side of isolation transformers.
• Secondary circuit – Low-voltage wiring between the transformer secondary and the fixture.

Frequently Asked Questions

1. What is airport lighting cable in simple terms?

2. Is FAA L-824 Type C 5kV only for primary circuits?

3. Can standard 5 kV medium-voltage cable replace FAA L-824 Type C 5kV?

4. How long does FAA L-824 Type C 5kV cable typically last in service?