Airfield Ground Lighting Design & Electrical Engineering
Designing the electrical system behind safe and reliable Airfield Ground Lighting. AGL design is more than selecting fixtures — it's a coordinated engineering process spanning runway and taxiway layout, series circuits, Constant Current Regulators, isolating transformers, cable, connectors, earthing, control, monitoring, loading and reliability.
What Is AGL Design?
AGL design is the engineering process of converting an airport's operational and lighting requirements into a complete, coordinated airfield lighting system.
A typical design considers the aerodrome layout, runway and taxiway configuration, approach requirements, the lighting systems required, fixture locations, circuit configuration, CCR selection, series-circuit cable, isolating transformers, connectors, control and monitoring, earthing and bonding, electrical loading, installation requirements, and testing and commissioning.
Not a Drawing Exercise
AGL design should not be treated as producing a set of drawings — it is a complete engineering process from layout through commissioning.
Electrically Coordinated
The objective is a system that is technically appropriate, electrically coordinated, maintainable and compliant with the applicable requirements and standards.
Serves the Pilot
Every design decision ultimately supports the same purpose: giving pilots reliable, correctly performing visual guidance.
The AGL Design Process
A complete AGL design can be understood as a connected sequence, from the airport layout through to photometric verification of the installed system.
This connection between design, installation, testing and photometry is important. AGL design should not be treated as a drawing exercise — it is a complete engineering process that only finishes once the installed system has been verified against the design.
Start from how the aerodrome will operate and which documents govern, then carry every requirement into layout, circuits, equipment and review.
AGL Visual Encyclopedia: How do requirements flow through AGL design Design
Understanding the AGL Series Circuit
One of the fundamental concepts in AGL electrical engineering is the series circuit. The system is designed so that the required current is maintained through the circuit while individual fixtures remain electrically isolated from the high-voltage primary circuit.
A constant current loop out from the CCR, through each isolating transformer and fixture, and back — enclosure and structure bonded to earth throughout
CCR & Circuit Load Estimator
CCR selection should be based on the actual system design rather than simply the number of lights. Adjust the sliders to see how fixture count, unit load and estimated losses combine into a total circuit requirement.
This is an illustrative estimator, not a design calculation. A real AGL load calculation must use the actual manufacturer transformer and CCR data, cable characteristics, circuit length and applicable spare-capacity margin for the specific project.
CCR, Transformer & Cable Engineering
These three components sit at the electrical heart of the series circuit and must be selected together, not independently.
CCR Design
Selection requires consideration of required circuit current, number of fixtures, transformer ratings, circuit load, CCR capacity, intensity steps, cable characteristics, circuit length, control and monitoring requirements.
Isolating Transformers
Selection may involve fixture wattage, primary current, secondary requirements, transformer rating, connector configuration, installation environment, applicable specification and system compatibility.
Series-Circuit Cable
Considerations include cable voltage rating, conductor size, circuit length, installation method, insulation characteristics, environmental conditions, cable joints, connector compatibility and insulation resistance.
Considered as an Integrated System
A change in one component can affect the overall system — component compatibility should be checked during the design stage rather than discovered during installation.
Four decisions, taken in order, that narrow the choice to the right constant current regulator for a series circuit.
AGL Visual Encyclopedia: A CCR selected Transformer selection Cable selection
Voltage Drop & Circuit Performance
Electrical calculations should consider the complete circuit rather than only individual components. Depending on circuit arrangement and design methodology, checks may include:
Cable Losses
Conductor resistance and circuit length effects.
Transformer Characteristics
Losses and performance under load.
Circuit Loading
Total connected load versus rated capacity.
CCR Operating Conditions
Output current, voltage headroom and step behaviour.
The objective is to ensure that the complete system operates within the required electrical and operational parameters — not simply that each component individually meets its own rating.
In a constant-current loop, current stays fixed — so the CCR must raise its output voltage to overcome the accumulated impedance of cable and transformers
AGL Circuit Loading
A series circuit may contain a significant number of lighting fixtures. The design needs to establish clear answers to a small set of recurring questions — particularly important when adding or replacing fixtures during airport modifications.
Questions the Design Must Answer
- How many fixtures?
- What is the load of each fixture?
- What transformer is required?
- What is the total circuit requirement?
- What CCR capacity is required?
- What happens if the circuit configuration changes?
A Change Cascades
A seemingly simple change — such as adding fixtures — can ripple through the entire circuit design:
- Circuit load
- Transformer requirement
- CCR capacity
- Cable performance
- Control configuration
How full the regulator is. The same circuit can leave a CCR comfortably loaded, nearly full or barely used, and each state has its own problems.
AGL Visual Encyclopedia: Circuit loading Circuit load
Control, Earthing & Protection
A complete electrical design also has to coordinate the control architecture, the earthing and bonding arrangement, and the protection philosophy with the series circuit and airport electrical system.
Control & Monitoring
CCR control, intensity selection, local and remote control, airport lighting control systems, fault monitoring, circuit status, CCR alarms, emergency operation and interface with airport systems.
Earthing & Bonding
Equipment earthing, metallic structure bonding, electrical equipment bonding, transformer and CCR installation, cable-related considerations and lightning protection interfaces where applicable.
Protection
Overcurrent protection, surge protection, equipment protection, lightning-related protection, insulation monitoring, earth-fault monitoring, emergency isolation and equipment interlocking.
The exact arrangement must be designed according to the applicable electrical standards, airport requirements and project specifications — protection philosophy should always be coordinated with the CCR, series circuit and airport electrical system as a whole.
The monitors and trips that guard a constant current regulator and its series circuit. Pick a fault, move the slider and see which device sees it, whether the CCR warns or shuts down, and what to check before any reset.
AGL Visual Encyclopedia: The CCR protection Control system architecture
Lighting Layout, Circuit Zoning & Segmentation
Electrical engineering cannot be separated from the physical AGL layout. Large systems often require multiple circuits or functional zones — good zoning makes troubleshooting and maintenance significantly easier.
Physical Layout Considers
- Runway lights
- Taxiway lights
- Centreline lights
- Approach lights
- PAPI
- Airfield signs
- Stop bars
- Runway guard lights
Circuit Zoning Considers
- Runway sections
- Taxiway sections
- Approach systems
- Operational requirements
- Maintenance requirements
- CCR allocation
- Redundancy
- Future expansion
The airfield is divided by area into approach, runway, taxiway and apron zones, so each can be switched, dimmed or closed on its own.
AGL Visual Encyclopedia: Airfield lighting zoning Circuit zoning
AGL Drawings & Engineering Documentation
A complete AGL design package can include several types of engineering drawings and schedules, each serving a distinct purpose.
AGL Layout Drawing
Shows the physical location of AGL equipment.
Series Circuit Diagram
Shows the electrical connection of the lighting circuit.
CCR Schematic
Shows the CCR and associated electrical/control interfaces.
Transformer Schedule
Lists transformer locations, ratings and associated fixtures.
Cable Schedule
Provides cable identification, route and circuit information.
Sign Schedule
Provides sign identification, type and electrical requirements.
Equipment Layout
Shows equipment locations and interfaces.
Earthing Layout
Shows relevant earthing and bonding arrangements.
Single-Line Diagram
Provides an overall representation of the electrical system.
One-line representation from incoming supply to the series circuit — actual drawings show all circuits, ratings and protective devices
AGL BOQ, Equipment Schedule & Design Calculations
Design information must ultimately translate into procurement and construction information, and every calculation should be traceable to the actual project configuration.
A Typical AGL BOQ Includes
Typical Design Calculations
Adding up every watt a series circuit draws, from the fixtures, the transformers and the cable, so the regulator that feeds it is the right size.
AGL Visual Encyclopedia: The load on a circuit calculated
Airfield Lighting Design Basics & Layout Design
The starting principles of airfield lighting design and how the layout is set out.
Airfield lighting design
Airfield lighting design is the process of deciding what lighting a runway, taxiway or apron needs and how it will be powered, controlled and maintained. It covers the lighting layout, series circuits, CCR sizing, transformers, cables, control and documentation, all checked against the standard the aerodrome follows. See The AGL Design Process section above.
Airfield lighting design basics
The basics are few. Lighting is fed from constant-current series circuits, each light has its own isolating transformer, a CCR sets the circuit brightness, and the layout, intensity and colour of each lighting system follow ICAO Annex 14 or the national equivalent. Everything else in the design builds on these points. See Understanding the AGL Series Circuit above.
Airfield lighting layout design
Airfield lighting layout design places each light in the correct position, spacing and orientation relative to the runway, taxiway or approach geometry. It also splits the lights into circuits so the failure of one circuit does not leave the airfield without guidance. Spacings and patterns come from the standard, so none are given here. See Lighting Layout, Circuit Zoning & Segmentation above.
Edge, threshold, touchdown zone, centreline and end lights each have a fixed place, spacing and colour along the runway.
AGL Visual Encyclopedia: How are runway lights laid out Taxiway lighting layout Approach light layout
Design Drawings, Bill of Quantities, Design Review & Rehabilitation Design
The documents that carry the design and the checks that prove it, including work on existing airfields.
Airfield lighting design drawings
Airfield lighting design drawings show light positions, circuits, cable routes, ducts, CCR and equipment room layouts, and the single line diagram. They are the main reference for construction, testing and later maintenance, so they must be complete, consistent and kept as-built. See AGL Drawings & Engineering Documentation above.
AGL bill of quantities
An AGL bill of quantities lists the fixtures, transformers, cables, connectors, CCRs, civil items and other work in a project, with descriptions, units and quantities. It is derived from the drawings and equipment schedule and should be cross-checked against design calculations. A clear bill of quantities helps tendering, cost control and ordering. See AGL BOQ, Equipment Schedule & Design Calculations above.
Airfield lighting design review
An airfield lighting design review checks the design before it is built. A typical review tests the layout against the standard, the circuit loading and voltage drop calculations, CCR and transformer selection, earthing, control, drawing consistency and maintainability. Reviews are often done at set stages, such as concept, detailed design and pre-construction. See the AGL Design Checklist below.
Airfield lighting rehabilitation design
Airfield lighting rehabilitation design covers upgrading or replacing lighting on an existing airfield. It starts with a survey of existing cables, ducts, circuits and equipment, then decides what can be reused and what must be replaced. It must also plan how work will be phased so the airfield stays operational, and how new equipment will work with existing CCRs and circuits.
AGL Design Checklist
Before construction, the design should be systematically checked across four areas. Tick items off as you review a project — this resets on reload.
Airport Layout
Electrical
Equipment
Documentation
Define the item, gather the sources, follow every reference, fix the editions, test each standard against its scope, and record the list.
AGL Visual Encyclopedia: How do you identify the applicable standards for an AGL item Standard selection flowchart
Design Changes & Modifications
Airport lighting systems are frequently modified — new taxiway construction, runway extension, fixture replacement, LED upgrades, CCR replacement, circuit modification, new signs, PAPI modification, new approach lighting or circuit expansion. Every modification should be evaluated against the existing electrical system.
AGL Design, Photometry, Commissioning & Maintainability
Design & Photometry
The designer establishes where the light is installed, what type of light is installed, how it is powered, how it is controlled and how it is aligned. Photometry then verifies how the installed light actually performs.
Design & Commissioning
A good design should make commissioning easier — the documentation should provide enough information to verify correct fixture installation, transformer selection, circuit connection, cable identification, CCR assignment, control configuration and intensity operation.
Design defines the intended system. Photometry verifies the optical result.
Design for Maintainability
- Equipment accessibility
- Cable identification
- Circuit identification
- Transformer identification
- Spare capacity
- Replacement compatibility
- Maintenance isolation
- Test points
The Engineering Cycle
Design for operation. Design for maintenance. Design for the future. A functional design that is difficult to maintain is an incomplete design.
Common AGL Design Mistakes
Recognising these recurring mistakes early in a project is far cheaper than correcting them after installation.
Selecting Independently
Choosing equipment component-by-component rather than as a coordinated system.
Ignoring Total Loading
Not establishing the total circuit loading across the full series circuit.
Layout / Circuit Mismatch
Not coordinating the electrical circuit with the physical lighting layout.
Poor Cable Routing
Insufficient attention to cable routing and identification.
Poor Documentation
Weak documentation of transformer and fixture locations.
Ignoring the Future
Not allowing for future modifications or expansion.
Photometry as an Afterthought
Treating photometry as completely separate from the design process.
Generic Calculations
Using generic calculations without checking actual project conditions.
Uncoordinated Deliverables
Failing to coordinate drawings, schedules and the BOQ.
No Final Verification
Not verifying the final installed configuration against the design.
The Complete AGL Engineering Cycle
An AGL system should be designed as a complete system, not as a collection of individual products — the CCR, series circuit, cable, isolation transformers, connectors, fixtures, control system, monitoring system and airport layout must work together from design through operation.
Understand how airport ground lighting systems, visual aids, electrical circuits and control equipment fit together in a typical airport layout.
AGL Visual Encyclopedia: What does a complete AGL airport layout look like
AGL Engineering Disciplines
AGL engineering sits at the intersection of several disciplines — a successful AGL system requires them to work together.
Quick Knowledge Check
Q1. What isolates individual AGL fixtures from the high-voltage series circuit?
Q2. CCR selection should primarily be based on:
Q3. Adding fixtures to an existing series circuit can affect:
Explore More AGL Engineering
AGL Fundamentals
Build your understanding of the complete Airfield Ground Lighting system.
Open AGL Fundamentals →AGL Photometry
Verify the optical performance of the installed system.
Open AGL Photometry →Standards Companion
Understand ICAO, FAA, IEC, IS and other applicable technical references.
Open the Standards Companion →AGL Cables & Connector Engineering
Primary and secondary circuit hardware selection.
Open Cables & Connectors →AGL Isolating Transformers
The fixture interface within the series circuit.
Open Isolating Transformers →Constant Current Regulators
CCR sizing and series-circuit power supply.
Explore CCR Engineering →AGL Installation & Commissioning
Turning the design into a field-verified system.
Open Installation & Commissioning →AGL Testing & Inspection
Electrical and photometric verification of the design.
Open Testing & Inspection →Design It Right. Build It Once.
From airport layout to energized circuit, from electrical calculation to photometric verification — explore the complete AGL design and electrical engineering knowledge base.
Explore the AGL Engineering Knowledge Hub
Fundamentals
Standards & Compliance
Runway, Taxiway & Approach Lighting
Surface Movement & Safety
PAPI
Electrical Engineering & Power
Photometry & Testing
Maintenance, Inspection & Safety
Resources, Documentation & Careers
Frequently Asked Questions
Q1What is AGL design?
AGL design is the engineering process of converting an airport's operational and lighting requirements into a complete, coordinated airfield lighting system. It covers aerodrome layout, lighting systems, fixture locations, circuit configuration, CCR selection, series-circuit cable, isolating transformers, connectors, control and monitoring, earthing and bonding, electrical loading, installation, and testing and commissioning.
Q2What are the stages of the AGL design process?
The sequence runs from airport layout and operational requirements through lighting system selection, fixture layout, circuit planning, electrical load calculation, CCR selection, transformer and connector selection, cable design, earthing and protection, control and monitoring, drawings and BOQ, installation, testing and commissioning, and finally photometric verification of the installed system.
Q3Why do AGL systems use a series circuit?
The series circuit is designed so that the required current is maintained through the circuit while individual fixtures stay electrically isolated from the high-voltage primary circuit. A constant-current loop runs from the CCR through each isolating transformer and fixture and back to the CCR.
Q4How is a CCR selected for an AGL circuit?
CCR selection should be based on the actual system design rather than simply the number of lights. Factors include required circuit current, number of fixtures, transformer ratings, circuit load, CCR capacity, intensity steps, cable characteristics, circuit length, and control and monitoring requirements.
Q5Why does CCR output voltage rise with every transformer in the loop?
In a constant-current loop the current stays fixed, so the CCR must raise its output voltage to overcome the accumulated impedance of the cable and every transformer on the loop. This is why CCR sizing considers rated output voltage, not just current.
Q6What happens to the design when fixtures are added to a circuit?
A seemingly simple change such as adding fixtures can cascade through the design, affecting circuit load, transformer requirement, CCR capacity, cable performance and control configuration. This is particularly important when adding or replacing fixtures during airport modifications.
Q7What does a voltage drop and circuit performance check involve?
It considers the complete circuit rather than individual components: cable losses, transformer characteristics, circuit loading and CCR operating conditions such as output current, voltage headroom and step behaviour. The aim is that the whole system operates within the required parameters, not merely that each component meets its own rating.
Q8What do earthing, bonding and protection cover in AGL design?
Earthing and bonding cover equipment earthing, metallic structure bonding, transformer and CCR installation, and lightning protection interfaces where applicable. Protection covers overcurrent and surge protection, equipment protection, insulation and earth-fault monitoring, emergency isolation and interlocking. The arrangement must follow the applicable standards, airport requirements and project specifications.
Q9Why is circuit zoning important in AGL design?
Large systems often need multiple circuits or functional zones, and good zoning makes troubleshooting and maintenance significantly easier. Zoning considers runway and taxiway sections, approach systems, operational and maintenance requirements, CCR allocation, redundancy and future expansion.
Q10What drawings and schedules make up an AGL design package?
A complete package can include an AGL layout drawing showing equipment locations, a series circuit diagram, a CCR schematic, a transformer schedule and a cable schedule, among other engineering drawings and documentation, each serving a distinct purpose.
Engineering & Expert Notes
Design the Circuit Around Serviceability
DesignPosition access points, spare capacity and sectioning so that faults can be isolated and repaired without taking the whole airfield out of service.
Leave Margin in CCR Loading
LoadingA circuit designed exactly to capacity leaves no room for later additions, cable ageing or higher losses. Agree and record the margin policy early.
Voltage Drop and Insulation Are Both Constraints
CablesCheck cable length against the CCR's available output voltage and verify the insulation rating for the primary voltage. A design can fail on either one.
Earthing and Surge Protection Belong in the First Layout
ProtectionAdding protection late tends to produce compromises. Integrate earthing, bonding and surge devices into the original drawings and schedules.
Drawings and Schedules Must Agree
DocumentationMismatches between single-line diagrams, layout drawings and bills of quantities cause site errors. Cross-check them before issue.
Run a Design Review With Operations and Maintenance
ReviewPeople who will run the system often see access, control and spares issues the designer cannot. Invite them before construction starts.
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