Low Intensity Runway Light
An economical and energy-efficient runway lighting solution designed for non-precision runways, VFR operations, and airports with lower traffic volumes. Low intensity lights provide adequate visibility for visual flight rules (VFR) operations and serve as an excellent entry-level solution for smaller airfields.
Image disclaimer: For identification and illustration only. It may show a product by another manufacturer and may not depict the exact item described; it is not a statement of any product’s quality, approval or performance. Third-party image and trademark rights belong to their owners. See full notice.
What Is It?
A Low Intensity Runway Light is an economical and energy-efficient runway lighting solution designed for non-precision runways, VFR operations, and airports with lower traffic volumes. These lights provide adequate visibility for visual flight rules (VFR) operations and serve as an excellent entry-level solution for smaller airfields, heliports, and general aviation airports. Low intensity lights typically operate at lower current levels (2.8A – 4.1A) and consume less power than their medium and high intensity counterparts, making them ideal for budget-conscious installations or airports with limited electrical capacity.
Purpose & Function
The purpose of the low intensity runway light is to match the lighting investment to the actual operating environment rather than defaulting to the highest specification available. A VFR airfield or general aviation strip has no operational need for the candela output built for CAT II/III approaches, and installing that level of fixture would mean paying for CCR capacity, transformers, and power infrastructure that never gets used. By providing exactly the visibility a visual approach requires — enough for a pilot to identify the runway and delineate it clearly at night, without more — this fixture lets smaller airfields and heliports achieve full lighting compliance within a realistic budget and electrical capacity, which is often the difference between an airfield being able to support night operations at all or not.
Where Is It Used?
Low intensity runway lights are used in a variety of applications where minimum visibility is required:
- Non-precision runways with visual approach operations (VFR)
- General aviation airports with low traffic volumes
- Heliports where lower intensity is sufficient
- Remote and regional airstrips with limited electrical capacity
- Taxiways and aprons where only basic illumination is required
- Emergency landing strips requiring minimal lighting
Installation & Location
Fixtures mount on a frangible coupling atop an L-867-type base can, or seat into an inset base can where the runway surface and load requirements call for a flush fixture, set out at the wider spacing typical of non-precision and general-aviation runways. Given these installations often serve airstrips with limited electrical infrastructure, cable runs from each base can back to the isolating transformer and CCR are kept as short and simple as the runway layout allows, with setting-out tied to the runway centreline survey; elevated fixtures are the more common choice at low-traffic and remote strips where load rating for inset units is less critical.
How Does It Work?
Low intensity runway lights operate using standard AGL principles with lower power requirements:
- Power: Powered from the constant current series circuit via an isolating transformer (typically 15W – 45W).
- Light Source: Utilizes LED arrays or low-wattage halogen lamps (15W – 45W).
- Beam Pattern: Projects a symmetric or omni-directional beam pattern suitable for visual approaches.
- Intensity Control: CCR-controlled intensity with 3 to 5 steps (2.8A – 5.2A), typically limited to lower settings.
Why low intensity fixtures are wired to the lower half of the CCR step range
CCR Series Circuit
Full 5-step range available on the loop: 2.8A → 3.4A → 4.1A → 5.2A → 6.6A
Isolating Transformer
Steps circuit current down to the fixture's 15W–45W rating
Low Intensity Fixture
LED array or low-wattage halogen source
Fixture's operating range — output scales with current up to 200–2,000 cd
Not used for this fixture type — reserved for medium/high intensity lights sharing the same series loop
Matched to Visual & Non-Precision Use
Sized for taxiway edge and basic visual-approach guidance, not CAT II/III precision operations
System Architecture & Control Logic
Low intensity runway lights are not individually addressable — control is exercised at the loop level through the constant current series circuit, which they typically share with medium and high intensity fixtures elsewhere on the same field. An ALCMS or, at the small and general-aviation strips where this fixture is most common, a simple local panel or pilot-controlled lighting (PCL) system selects the brightness step, and the CCR regulates the whole loop to that fixed current. Because a low intensity fixture's useful output range tops out well below the loop's maximum step, the loop is generally never driven to its highest setting unless other, higher-output fixtures share the same circuit and require it — the low intensity light simply rides along at whatever current the loop is running. Every fixture on the loop, via its own isolating transformer, draws that same current and burns at the same intensity simultaneously, so there is no way to control this fixture independently of the others on its circuit. Fault detection is loop-based: the CCR monitors loop voltage against commanded current, and a voltage rise — typically an open-circuit lamp or a failed isolating transformer — is reported as a loop fault rather than pinpointed to an exact fixture without further sectionalised testing.
Loop-level control: the low intensity fixture rides the same commanded current as everything else on its circuit
ALCMS / PCL Panel
Selects the required brightness step for the loop
Constant Current Regulator
Regulates the whole series loop to one fixed current
Shared Series Circuit Loop
Same current for every fixture on the loop — no individual control
Isolating Transformer
Taps fixed loop current down to this fixture's 15W–45W rating
Low Intensity Fixture Output
Tracks the loop step; faults reported to the ALCMS as a loop-level fault, not a fixture ID
Physical Construction
The fixture body is a compact die-cast aluminium housing, lighter and simpler than its medium- and high-intensity counterparts since the lower-output LED array or 15–45W halogen lamp behind the lens generates far less heat to manage. The lens is glass or polycarbonate, gasket-sealed for an IP67/IP68 rating, and the unit mounts either on a frangible coupling over an L-867 base can for elevated installations or directly into an L-868 base can for inset units rated for aircraft wheel loading. Wiring runs to an L-823 primary connector feeding the isolating transformer's secondary leads in its own base can nearby, with stainless-steel fasteners and a base-can drainage provision — the same fundamental construction as the rest of the runway-light family, scaled down to match the lower intensity steps this fixture is built to deliver.
Technical Parameters
| Parameter | Typical Value |
|---|---|
| Light Source | LED array or 15W – 45W halogen |
| Colour | White (standard) or Yellow (caution) |
| Luminous Intensity | 200 – 2,000 candela (depending on setting) |
| Intensity Steps | 3 to 5-step (2.8A – 5.2A) CCR controlled |
| Beam Pattern | Symmetric, omnidirectional, or basic directional |
| Mounting Type | Elevated (frangible) or Inset (flush) |
| Load Capacity (inset) | 100,000 kg (220,000 lbs) wheel load |
| Isolating Transformer | 15W – 45W (6.6A series circuit) |
| Protection Class | IP67 / IP68 (submersible) |
| Operating Temperature | -40°C to +55°C |
Electrical Requirements
| Requirement | Typical Value |
|---|---|
| Circuit Type | Series circuit, constant current (CCR fed) |
| Rated Series Current | 5.2A / 6.6A (3 to 5-step: 2.8A – 5.2A) |
| Isolation | Via dedicated isolating transformer (15W/45W), not directly connected to series loop |
| Transformer Secondary | Matched to fixture wattage; sized to series circuit rating |
| Cable Type | L-824 single-conductor, direct-burial rated, 5kV or 600V per circuit design |
| Connector | L-823 primary connector, submersible-rated splice |
| Insulation Resistance | ≥ 50 MΩ (megger test, cable-to-ground) |
| Earthing/Grounding | Fixture body and base can bonded to airfield earth grid |
| Fault Protection | CCR-level ground fault and open-circuit detection |
| Power Source | CCR output, regulated per ICAO/FAA intensity step schedule |
Photometric Requirements
| Parameter | Typical Value |
|---|---|
| Main Beam Intensity (White) | ≥ 1,200 cd on-axis, up to 2,000 cd at full intensity |
| Main Beam Intensity (Yellow, Caution) | ≥ 600 cd on-axis, up to 1,000 cd at full intensity |
| Beam Pattern | Symmetric, omnidirectional, or basic directional per site configuration |
| Vertical Beam Spread | ± 5° about set axis (directional) or full hemisphere (omnidirectional) |
| Isocandela Distribution | Per ICAO Annex 14 Attachment A / FAA AC 150/5340-30 figures for low-intensity runway lights |
| Chromaticity | Within ICAO Annex 14 white or yellow boundary as applicable (CIE coordinates) |
| Intensity Tolerance | ± 25% of rated value at each CCR step (field measurement) |
| Maintenance Factor | ≥ 50% of new-fixture intensity before lamp/lens replacement is due |
| Test Method | Mobile photometric van/goniophotometer or fixed test bench per fixture |
Applicable Standards
ICAO Annex 14
Low intensity light requirements for non-precision runways
FAA AC 150/5345-46
Specification for low intensity runway lights
IEC TS 61827
Characteristics of inset and elevated luminaires used on aerodromes and heliports
FAA AC 150/5345-53
Airport Lighting Equipment Certification Program - photometric testing and certification requirements applicable to LED and other AGL fixtures
Installation Requirements
Base Can Excavation & Grade
CivilExcavate and compact the sub-grade before setting the L-867-type base can (or inset base can where flush mounting is required), holding the can top level and flush with the surrounding surface.
Setting-Out to Centreline Survey
CivilSet out fixture positions from the runway centreline survey at the wider spacing typical of non-precision and general-aviation runways.
Duct & Cable Route
ElectricalLay the series circuit duct/cable route as short and direct as the runway layout allows, reflecting the limited electrical infrastructure typical of these installations.
L-823 Connector Termination
ElectricalTerminate and seal the primary connector per manufacturer procedure, keeping the splice submersible-rated before backfill.
Isolating Transformer Matching
ElectricalConfirm the isolating transformer wattage and ratio match the fixture and the series circuit's rated current step before connection.
Frangible Coupling / Base Fixing
MechanicalTorque the frangible coupling or inset base fixing bolts to the specified value, confirming the fitting shears as designed under lateral load.
Elevation & Aim Setting
MechanicalSet fixture height and beam aim against the design aiming diagram, keeping elevated units within the frangibility height limit.
Pre-Energisation Sign-off
DocumentationRecord base can position, cable route, connector seal, and torque values as-built before backfill.
Testing & Commissioning
Insulation Resistance (Megger) Test
Pre-EnergisationMegger-test the isolating transformer and series loop before the circuit is energised, confirming insulation resistance clears the acceptable minimum.
Loop Continuity & Resistance Test
Pre-EnergisationVerify series loop continuity end to end and record total loop resistance, ruling out open circuits or high-resistance splices.
Primary/Secondary Voltage Verification
EnergisationWith the CCR energised, confirm secondary voltage at the fixture's isolating transformer matches the rated ratio at the commissioned current step.
CCR Brightness Step Response
EnergisationCycle the CCR through its lower intensity steps (2.8A-5.2A) and confirm the fixture responds correctly at each.
Fixture Alignment & Aim Verification
Final AcceptanceCheck elevation and beam orientation of each fixture against the design aiming diagram, correcting any deviation before sign-off.
Photometric Commissioning Test
Final AcceptanceMeasure beam intensity and beam spread with a calibrated photometer against ICAO/FAA commissioning tolerances for low intensity fixtures.
Frangibility & Mounting Verification
Pre-EnergisationConfirm the frangible coupling and base can depth meet as-built tolerances before the site is finally backfilled.
Documentation & As-Built Sign-off
Final AcceptanceRecord insulation, continuity, voltage, and photometric readings alongside as-built position in the commissioning dossier for handover.
Inspection & Maintenance
Photometric Output Check
AnnualVerify beam intensity against rated values to confirm adequate visibility for the fixture's intended operations.
Lens Cleaning
QuarterlyClean the lens of rubber deposits and debris to maintain light output.
Power Supply Check
AnnualVerify power input stability and inspect the supply for signs of stress or ageing.
Common Field Issues
Insufficient Visibility for IFR Operations
Low intensity lights are not suitable for instrument approaches or low visibility operations. Airports upgrading to IFR operations must upgrade to medium or high intensity lighting.
Lens Contamination
Like all runway lights, low intensity lights are exposed to rubber deposits, dust, and de-icing fluids. Regular cleaning is required to maintain adequate light output.
Power Supply Limitations
Low intensity installations may be served by smaller transformers and cables that limit future upgrades. Consider installing infrastructure for future expansion when planning low intensity systems.
Troubleshooting Guide
Reduced Light Output or Dull Lens Appearance
Visibility Reported as Marginal in Low-Visibility Conditions
Voltage Drop or Limited Capacity for Circuit Expansion
Failure Modes & Root Causes
Lens Contamination
Intensity Classification Mismatch
Circuit Infrastructure Undersizing
Safety & Operational Notes
Series Circuit Isolation
Electrical SafetyLow intensity runway lights run on a constant-current series circuit that can carry several kV across the loop. De-energise and lock out the CCR, then verify zero energy at the fixture before opening a base can or handling cable connectors.
Airside Work Coordination
OperationalAny work on or near an active runway requires ATC/airside coordination and a NOTAM where the fixture will be dark or out of tolerance, with vehicle and personnel movement kept clear of the runway strip per the aerodrome's safety management procedures.
Frangibility Not to Be Defeated
MechanicalNever substitute the frangible coupling with a rigid fitting or over-torque it during installation or repair; the coupling must still shear cleanly on aircraft impact to limit damage under the frangibility requirement.
Match Intensity Class to Operating Category
ComplianceConfirm the low intensity classification remains appropriate for the runway's current visibility minimums before returning it to service; do not treat marginal visibility reports as a fixture fault when the underlying issue is a mismatch between the installed intensity class and the operation being flown.
FOD Control at the Base Can
OperationalKeep tools, fasteners, and removed gaskets accounted for at all times when the base can is open, and secure or remove any loose material before reinstating the fixture, to prevent foreign object debris on the movement area.
Insulation Test Before Re-Energisation
Electrical SafetyAfter any cable, connector, or transformer work, megger test the affected series loop before restoring power, since a residual fault at re-energisation can trip the CCR or damage healthy fixtures on the same circuit.
PPE & Grounding
Personnel SafetyUse insulated tools and appropriate PPE when working on series-circuit connections, and confirm the fixture and base can are bonded/grounded per the electrical design before reconnecting the loop.
Restore to Compliant State
ComplianceDo not leave a fixture out of aim tolerance, at reduced intensity, or otherwise non-compliant after maintenance; verify photometric and positional conformance before closing out the work and cancelling the associated NOTAM.
Engineering & Expert Notes
Low Intensity Doesn't Mean Low Scrutiny in Marginal Light
OperationalLow intensity fixtures are often installed at aerodromes with limited or no approach lighting, so pilots rely on them more heavily in dawn, dusk, and light haze conditions than the classification name suggests. Photometric drift that would be tolerable on a high-intensity runway can matter more here.
Vegetation Growth Is a Bigger Risk Than on Larger Fields
MaintenanceSmaller aerodromes with low intensity lighting often have less frequent grounds maintenance cycles; grass and vegetation growth around inset or low-profile fixtures can obstruct the beam well before it's caught on a scheduled inspection. Build a vegetation check into the routine cycle rather than relying on incident reports.
Standalone Solar/Battery Installations Need Seasonal Margin
ElectricalWhere low intensity lighting runs on a standalone solar-charged system rather than a mains-fed CCR, size battery capacity against the shortest-daylight month at the site's latitude, not an annual average, or output will sag exactly when winter dusk arrivals need it most.
Confirm Classification Still Matches Runway Use
ComplianceA runway's operational category can change over years of service — new instrument approaches, upgraded traffic, or revised visibility minimums — without every part of the lighting system being re-evaluated. Periodically confirm the low intensity classification is still appropriate rather than assuming the original design basis still holds.
Snow Banking Hides Low-Profile Fixtures First
SeasonalLow intensity fixtures typically sit lower to the pavement than medium or high intensity equivalents, so windrow snow banking from clearing operations buries them sooner. Coordinate snow clearing setback distances specifically for low-profile lighting rather than applying a single blanket clearance standard.
Trend Loop Readings on Longer Rural Runs
TroubleshootingLow intensity installations often serve longer, more remote cable runs than lighting on busier fields. Insulation resistance degradation from moisture ingress can develop gradually over a longer loop; trending megger readings across visits catches a slow fault before it takes the whole loop down.
Frequently Asked Questions
Short answers about low intensity runway lights: use, intensity, limits, standards, maintenance and common faults.
Q1What is a low intensity runway light?
A low intensity runway light is an economical, energy-efficient runway fixture for non-precision runways, VFR operations and lower-traffic airports. It provides adequate visibility for visual flight rules operations and is a common entry-level solution for smaller airfields.
Q2Where are low intensity runway lights used?
Typical uses are non-precision VFR runways, general aviation airports, heliports, remote and regional airstrips with limited electrical capacity, taxiways and aprons needing basic illumination, and emergency landing strips.
Q3How bright is a low intensity runway light?
Output is roughly 200 to 2,000 cd depending on the setting, with at least 1,200 cd on-axis for white and 600 cd for yellow caution lights. The fixtures typically use 3 to 5 CCR steps between 2.8 A and 5.2 A.
Q4Can low intensity runway lights be used for instrument approaches?
No. They are not suitable for instrument approaches or low-visibility operations. An airport moving to IFR operations must upgrade to medium or high intensity runway lighting.
Q5What transformer and light source does a low intensity runway light use?
It is fed from the constant current series circuit through an isolating transformer of roughly 15 W to 45 W, and uses an LED array or a low-wattage halogen lamp. Mounting can be elevated (frangible) or inset.
Q6Which standards apply to low intensity runway lights?
The main references are ICAO Annex 14, FAA AC 150/5345-46, IEC TS 61827 and FAA AC 150/5345-53. Always verify the current edition and your aerodrome's approved requirements.
Q7How often should low intensity runway lights be maintained?
Typical intervals are quarterly lens cleaning and annual photometric output and power supply checks. Your airport's approved maintenance programme takes precedence.
Q8What should be considered when planning a low intensity system?
Small transformers and cables can limit future upgrades, so it is worth installing infrastructure with expansion in mind. Lenses also need regular cleaning because of rubber deposits, dust and de-icing fluids.
Related Components
Go Beyond the Component. Understand the Complete AGL System.
You have explored the component. Now understand how it works within the complete Airfield Ground Lighting system.
Learn AGL from fundamentals to design, installation, testing, photometry, commissioning, maintenance and troubleshooting through structured technical training at Precision AGL Academy.
Build practical knowledge. Understand the circuit. Read the standards. Troubleshoot with confidence.
Your next step in AGL starts here.
Need expert guidance on low intensity runway light selection or installation?
Precision AGL Academy provides advice on cost-effective lighting solutions, VFR requirements, and field testing of low intensity systems.
Follow the Academy
Important Notice, Disclaimer & Limitation of Liability
Please read before relying on any content on this page.
- Purpose and intended users. This page on Low Intensity Runway Light is an independent educational and informational reference for competent, suitably trained and authorised airfield ground lighting (AGL) and aerodrome electrical personnel. It is not professional engineering, legal or regulatory advice, and using it does not create any professional or client relationship.
- Safety. Work on series circuits, constant current regulators (CCRs), isolating transformers, cables, connectors and lighting equipment can be fatal. Always apply the aerodrome’s permit-to-work and isolation/LOTO procedures, prove dead, use correctly rated instruments and PPE, and follow the manufacturer’s instructions. Nothing here authorises work on live equipment or the bypassing of any safety device or interlock.
- Aviation operations. Nothing here authorises installation, modification, energisation, adjustment, return to service, a change of operating category (CAT I/II/III), a NOTAM or any aerodrome certification or approval decision. These rest with the aerodrome operator, the air navigation service provider and the competent regulator.
- Specifications, ratings and typical values. Descriptions, parameters, ratings, dimensions, photometric values, wattages, service lives, maintenance tasks and intervals, failure modes, certifications (for example CE, FCC, UL or IEC marks) and part or type designations are general, typical and indicative. They may not match any particular product, make, model or version, and they are not a datasheet, design, specification, selection, sizing, procurement or acceptance criterion. The manufacturer’s current documents, the approved design and the project specification prevail.
- Standards and regulations. References to ICAO, FAA, IEC, IEEE, ISO, BIS, DGCA and other standards are paraphrased summaries for orientation only. They may be incomplete or out of date, and standards are revised from time to time. Consult the current official editions. Following this content does not guarantee compliance with any law, standard or regulatory approval, and the regulator’s requirements always prevail.
- No warranty. Content is provided “as is” and “as available”, without warranty of any kind, express or implied, including accuracy, completeness, currency or fitness for a particular purpose. Real installations differ in design, equipment make and model, age and condition.
- Limitation of liability. To the fullest extent permitted by applicable law, Precision AGL Academy, Precision AGL Solutions and their owners, authors and contributors are not liable for any injury, death, loss, damage, downtime, penalty or regulatory consequence, whether direct or indirect, arising from the use of, reliance on, or inability to use this content. Nothing in this notice excludes or limits any liability that cannot lawfully be excluded or limited.
- Independence, brands and no endorsement. This is an independent publication. It is not affiliated with, sponsored by or endorsed by ICAO, the FAA, the IEC, DGCA, AAI, any airport, regulator, supplier or equipment manufacturer. Third-party names, product designations, standard designations and trademarks (including Megger®, Siemens, Eaton, Crouse-Hinds, ADB SAFEGATE, Fluke, ABB and Honeywell) belong to their respective owners and are used only for identification and description. Mention of a brand, product or supplier is not a recommendation, and we do not sell, supply or quote for any component described.
- Images and third-party content. Images and illustrations are shown to help identify the type of component. They may show products of various manufacturers, may not depict the exact item described, and are not a statement about any product’s quality, approval or performance. Copyright and trademarks in third-party images, logos and photographs belong to their respective owners and are not claimed as ours. If you are a rights holder and want an image removed, replaced or credited, email precisionaglsolutions@gmail.com with the page address and we will act promptly.
- Training and services. Mentions of training, courses, consultation, advice, selection, installation, calibration or other support, including the “Learn…Certify” pathway, describe learning stages and are not an offer, quotation, tender or promise of any result. Contacting us or our replying creates no engagement or duty of care; an engagement exists only under a written agreement. We are not a regulator or certification body, and completing any course or reading this content is not a certification, accreditation or authorisation to work on any aerodrome.
- Copyright, privacy and corrections. © 2026 Precision AGL Academy. All rights reserved. Text, structure, compilations and diagrams may be viewed for personal reference and internal training only; any other copying, republication or commercial use needs our written permission. If you email, telephone or message us, we use your details only to respond and handle your matter, in line with applicable Indian law including the Digital Personal Data Protection Act, 2023; please do not send confidential or security-sensitive information. To display this page your browser requests fonts, icons and images from third-party servers, which receive your IP address and browser details under their own policies. Content is reviewed periodically with no obligation to update. To report an error, safety concern or rights issue, write to precisionaglsolutions@gmail.com.