AGL Electrical Components
AGL Circuit Selector Switch for Airfield Lighting Circuit Control
A controlled interface for selecting, isolating or switching airfield lighting circuits
AGL Circuit Selector Switches provide a controlled interface for selecting, isolating or switching airfield lighting circuits according to the system design. Precision AGL Solutions supports circuit selector switch selection for airfield lighting installations and associated electrical control systems.
Supplied by Precision AGL Solutions
Product Overview
AGL Circuit Selector Switch
What It Is
Circuit selector switches can be incorporated into airfield lighting control arrangements where specific circuits or circuit sections need to be selected for operation, maintenance, testing or system configuration.
The switch configuration is selected according to the circuit arrangement, electrical characteristics, number of circuits, switching method, enclosure requirements, terminal configuration and airport project requirements.
Where FAA-type equipment is specified, the reference is the L-847 circuit selector switch (FAA AC 150/5345-5B), available as L-847-1 to L-847-4 for one to four circuit control.
Function in an AGL System
A circuit selector switch provides a controlled switching interface within an airfield lighting electrical system. Depending on the configuration, it may allow an operator or maintenance team to:
- Select a designated circuit
- Change between circuit positions
- Isolate a circuit for maintenance
- Establish a specified switching path
- Support testing activities
- Control circuit availability per the approved design
The switch should not be treated as a generic electrical switch without confirming its suitability for the specific AGL circuit. Electrical load, switching duty, circuit arrangement and required isolation method must be considered during selection.
Applications
Where Circuit Selector Switches Are Used
Circuit controlAirfield lighting circuit control.
Circuit selectionSelection between designated lighting circuits.
Maintenance switchingMaintenance switching arrangements.
Isolation & operationCircuit isolation and operational control.
Control panelsAirfield lighting control panels.
Airport electricalSelected airport electrical installations.
RehabilitationRehabilitation and modification projects.
Testing & commissioningTesting and commissioning arrangements.
ChangeoverCircuit changeover where specified by the system design.
The actual switching function should be established from the approved electrical schematic and airport lighting control philosophy.
System Compatibility
Select for the Complete Electrical System
Compatibility Factors
- Circuit type
- Nominal voltage
- Operating current
- Switching current
- Number of circuits
- Number of switch positions
- Switching sequence
- Required isolation
- Terminal arrangement
- Enclosure type
- Installation environment
- Control panel arrangement
- Airport operational requirements
CCR-Controlled Circuits
Where the switch is associated with a constant-current-regulator-controlled circuit, the switching arrangement should be coordinated with the CCR and overall series-circuit design.
The electrical load, switching duty, circuit arrangement and required isolation method must all be established before a switch is selected.
Technical Data
Specification Summary
| Parameter | Specification |
|---|---|
| Product Type | AGL Circuit Selector Switch |
| Application | Airfield lighting circuit selection and switching |
| Governing Specification | FAA AC 150/5345-5B (L-847), where FAA-type equipment is specified; otherwise as per project specification |
| Unselected Circuit Treatment | Short-circuited by the switch, never left open (L-847 type); confirm for other designs |
| Control Mode | Local and/or remote selection; optional door interlock, per specification |
| Current Rating | Model/configuration-specific |
| Voltage Rating | Model/configuration-specific |
| Number of Circuits | Project-specific |
| Number of Positions | Configuration-specific |
| Switching Method | Model-specific |
| Switching Duty | Application-specific |
| Contact Configuration | Configuration-specific |
| Terminal Arrangement | Model-specific |
| Enclosure | Configuration-specific |
| Cable Entry | Model/enclosure-specific |
| Mounting Arrangement | Panel or installation-specific |
| Environmental Protection | Application-specific |
| Operating Temperature | Model-specific |
| Insulation Characteristics | Manufacturer specified |
| Mechanical Construction | Model-specific |
| Identification | According to project requirements |
| Weight | Model-specific |
Note: Exact current rating, voltage rating, circuit capacity, contact arrangement, enclosure protection and dimensions should be confirmed against the selected switch manufacturer's technical documentation.
Circuit Selection Arrangement
Establish Circuits and Positions from the Approved Design
A selector switch may be configured for a specific number of circuits or positions depending on the intended application. Selection should consider:
- Number of circuits requiring control
- Required switch positions
- Normal operating position
- Maintenance or isolation positions
- Required interlocking, where applicable
- Switching sequence
- Circuit current and voltage
- Required terminal arrangement
- Operator identification
- Panel and enclosure requirements
The final configuration should correspond to the approved circuit-control schematic.
Switching Method
An Important Selection Parameter
Mechanism
Depending on the application, the switch may use a mechanical selector arrangement or another specified switching configuration. The selected mechanism should be suitable for the intended electrical duty and operating environment.
A selector switch should only be used for duties for which its electrical and mechanical ratings have been established.
Intended Duty
- Circuit selection
- Circuit isolation
- Changeover
- Maintenance switching
- Control-panel operation
- Testing
- Other project-specific switching functions
Installation
Install to Manufacturer Instructions and Approved Drawings
Installation Considerations
- Correct mounting orientation
- Adequate clearance
- Correct terminal identification
- Proper cable termination
- Suitable cable routing
- Secure mechanical mounting
- Protection from moisture and contamination
- Correct circuit identification
- Accessibility for operation and maintenance
Install where operators and maintenance personnel can safely access the switch without interfering with normal airfield operations.
Enclosure & Environmental Protection
Select the enclosure according to the installation environment. Where installed outdoors or within an airfield electrical facility, it should provide the protection required by the project specification.
- Indoor or outdoor installation
- Moisture exposure
- Dust
- Temperature variation
- Humidity
- Corrosive conditions
- Mechanical impact
- Cable-entry requirements
- Cleaning and maintenance activities
Terminals & Cable Connection
Verify Before Installation
Pre-Installation Checks
- Terminal identification
- Conductor size compatibility
- Connection method
- Cable-entry arrangement
- Tightening requirements
- Insulation clearance
- Circuit identification
Wiring
Terminal configuration should be compatible with the cable and wiring arrangement specified for the circuit-control system. All connections should be made according to the approved wiring diagram.
Incorrect terminal connections can result in unintended circuit operation or loss of circuit control.
Series-Circuit Switching Principle
Never Leave an Energised Circuit Open
How It Works
A series lighting circuit driven by a constant-current regulator must never be left open while energised. An L-847-type circuit selector switch connects the regulated output to the selected load circuit and, at the same time, short-circuits the series circuit that is not selected. This lets one regulator be assigned to a chosen circuit without any circuit being left open.
The FAA specification covers one- to four-circuit control types (L-847-1 to L-847-4), two enclosure classes, local selection with remote operation, and an optional door interlock switch.
Selection Consequences
- Confirm the switch short-circuits every unselected series circuit
- Match the switch voltage and current rating to the regulator output and circuit
- Confirm local/remote control and any door-interlock requirement
- Do not substitute a general-purpose changeover switch, contactor or disconnect for a series-circuit selector switch
- Operate the switch only as the manufacturer's instructions and site procedure allow
CCR Interface
Circuit Selector Switch and CCR
System Review
Where a selector switch forms part of a control system incorporating a Constant Current Regulator, the switching arrangement should be reviewed as part of the complete system. The CCR provides controlled series-circuit output, while the selector switch may provide a designated switching or selection function according to the system architecture.
The Interface Should Ensure That
- The switching arrangement is electrically compatible
- The CCR is not subjected to an unsuitable switching duty
- Unselected series circuits are short-circuited, and no switch position leaves an energised CCR output open
- Local/remote selection and any door interlock agree with the control philosophy
- Circuit selection follows the approved control philosophy
- Maintenance isolation is clearly defined
- Operator indications correspond to the actual circuit condition
The approved electrical schematic should take precedence over generic switching arrangements.
Maintenance, Inspection & Testing
Supporting Safe Maintenance
Maintenance Procedure
- Identify the affected circuit
- Confirm switch position
- Apply appropriate electrical isolation
- Verify de-energised condition where required
- Carry out maintenance activity
- Restore the correct switch position
- Verify function before returning to service
Switch position labels should remain clear and legible throughout the service life of the installation.
Visual Inspection
- Mechanical damage
- Loose mounting
- Damaged enclosure
- Corrosion
- Contamination
- Damaged cable entries
- Loose terminals
- Damaged labels
- Abnormal mechanical operation
Electrical Checks
- Contact continuity
- Correct circuit selection
- Correct switch-position indication
- Electrical isolation where applicable
- Terminal connection verification
- Functional operation
- Circuit-control verification
Test per the approved project procedure and the manufacturer's requirements.
Commissioning
After Installation or Replacement
- Verify the switch model and configuration
- Confirm all wiring against the approved schematic
- Check terminal connections
- Verify mechanical operation
- Confirm each switch position
- Verify the associated circuit selection
- Confirm isolation functionality where applicable
- Check operator identification and labels
- Record commissioning results
- Return the system to its approved normal operating configuration
Functional testing should be completed before the associated airfield lighting system is placed into normal operation.
Troubleshooting
Symptoms, Causes and Checks
Circuit Does Not Respond to Selector Position
Possible causes
- Incorrect wiring
- Incorrect terminal connection
- Faulty switch contacts
- Incorrect switch configuration
- Upstream circuit fault
- Downstream circuit fault
- Control-system fault
Check the selector switch and associated circuit systematically using the approved electrical schematic.
Circuit Remains Selected
Possible causes
- Incorrect contact configuration
- Mechanical selector fault
- Wiring error
- Incorrect switch position
- Downstream control fault
Verify the switch contact arrangement and wiring before replacing the component.
Switch Difficult to Operate
Possible causes
- Mechanical damage
- Contamination
- Corrosion
- Misalignment
- Excessive mechanical wear
Do not force the selector mechanism. Investigate the cause and replace the switch where required.
Incorrect Circuit Selected
Possible causes
- Incorrect wiring
- Incorrect circuit identification
- Incorrect switch configuration
- Incorrect panel labelling
Verify the complete circuit-selection arrangement against the approved drawings.
Replacement
Replacing an Existing Circuit Selector Switch
Confirm Before Replacing
- Existing switch type
- Number of circuits
- Number of positions
- Contact configuration
- Current rating
- Voltage rating
- Terminal arrangement
- Enclosure dimensions
- Mounting arrangement
- Cable-entry arrangement
- Existing wiring diagram
Principle
A replacement should provide equivalent or approved improved functionality without changing the circuit-control philosophy unless the modification has been formally engineered.
For retrofit applications, photographs of the existing switch, panel, terminals and identification labels can assist with configuration review.
Procurement Checklist
Before Requesting a Circuit Selector Switch
Please provide:
- Application description
- Number of circuits
- Required switch positions
- Current rating
- Voltage rating
- Switching duty
- Contact arrangement
- Enclosure requirement
- Mounting arrangement
- Terminal requirements
- Cable details
- Environmental conditions
- Existing switch details, for replacement
- Electrical schematic, where available
- Airport or project specification
Documentation & Standards
Technical Documentation and Compliance
Documentation
- Product datasheet
- Electrical specifications
- Contact configuration
- Terminal information
- Dimensional drawings
- Mounting details
- Wiring diagrams
- Installation instructions
- Operating instructions
- Inspection and testing information
- Project-specific technical documentation
Exact documentation depends on the selected circuit selector switch.
Standards & Compliance
The switch should be selected, installed and tested in accordance with the applicable airport project requirements and electrical installation practices. Depending on the project, references may include:
- FAA AC 150/5345-5B — Airport Lighting Circuit Selector Switch (L-847-1 to L-847-4)
- FAA AC 150/5345-10H — Constant Current Regulators and Regulator Monitors (interface)
- FAA AC 150/5345-53D — Airport Lighting Equipment Certification Program
- ICAO Annex 14 Vol. I (electrical systems and maintenance provisions) and Aerodrome Design Manual (Doc 9157) Part 5 — Electrical Systems
- IEC 61821 — Maintenance of aeronautical ground lighting constant current series circuits
- Airport authority, DGCA and project specifications, and manufacturer instructions
Applicable standard editions and project requirements should be confirmed for the specific installation.
Safety
Electrical Safety — Isolation and Lock-Out
WARNING — never open a live series circuit. An open series circuit driven by a constant-current regulator can produce dangerously high voltage. Opening, cutting or disconnecting any part of an energised circuit can cause serious injury or death and damage equipment.
- De-energise the circuit at the regulator and apply the site lock-out / tag-out (LOTO) procedure before any work
- Where the circuit must be isolated or shorted, use the series circuit cut-out switch or approved isolation device — not an improvised bypass
- Verify the circuit is de-energised and the output is isolated before touching conductors, connectors, splices or transformers
- Work only under the airport's permit-to-work system, using qualified personnel and the manufacturer's instructions
- Never operate or work on a selector switch in a way that leaves an energised regulator output open-circuited
- Follow the applicable national electrical safety regulations and site procedures
Why Choose Precision AGL Solutions
Selection Based on the Complete System
We support selection of airfield lighting electrical components based on the complete system arrangement. For circuit selector switch applications, our process considers:
- Circuit configuration
- Electrical ratings
- Switching requirements
- Number of circuits
- Installation environment
- CCR interface
- Existing equipment for retrofit projects
- Technical documentation
- Airport project requirements
This helps ensure the selected switch is appropriate for the intended circuit-control function rather than being selected solely by nominal voltage or current.
FAQ
AGL Circuit Selector Switch — Frequently Asked Questions
What is an AGL circuit selector switch?
It is a controlled switching interface that lets an airfield lighting system select, isolate or switch circuits or circuit sections for operation, maintenance, testing or system configuration, as set out in the approved design. It should not be treated as a generic electrical switch.
What is the L-847 circuit selector switch?
Where FAA-type equipment is specified, the reference is the L-847 under FAA AC 150/5345-5B, available as L-847-1 to L-847-4 for one to four circuit control. The specification also covers two enclosure classes, local selection with remote operation and an optional door interlock switch.
What happens to the circuits that are not selected?
A series lighting circuit driven by a constant-current regulator must never be left open while energised. An L-847-type switch connects the regulated output to the selected load circuit and at the same time short-circuits the series circuit that is not selected, so one regulator can be assigned to a chosen circuit without any circuit being left open. Confirm this behaviour for other designs.
Can a general-purpose changeover switch or contactor be used instead?
No. Do not substitute a general-purpose changeover switch, contactor or disconnect for a series-circuit selector switch. Electrical load, switching duty, circuit arrangement and the required isolation method must be established before selection.
How does a selector switch work with a CCR?
Review the arrangement as part of the complete system. It should be electrically compatible, the CCR should not be subjected to an unsuitable switching duty, unselected series circuits should be short-circuited with no position leaving an energised CCR output open, and local or remote selection and any door interlock should agree with the control philosophy. The approved electrical schematic takes precedence over generic arrangements.
Which parameters matter when selecting a switch?
Circuit type, nominal voltage, operating and switching current, number of circuits and switch positions, switching sequence, required isolation, terminal arrangement, enclosure type, installation environment, control panel arrangement and airport operational requirements. The voltage and current rating must match the regulator output and circuit.
How is a circuit selector switch installed?
Install it to the manufacturer instructions and approved drawings with correct mounting orientation, clearance, terminal identification, cable termination and circuit identification, protected from moisture and contamination and accessible for safe operation and maintenance. All connections should follow the approved wiring diagram, because incorrect terminal connections can cause unintended circuit operation or loss of circuit control.
What is checked at commissioning?
Verify the switch model and configuration, confirm all wiring against the approved schematic, check terminal connections, verify mechanical operation, confirm each switch position and the associated circuit selection, confirm isolation functionality where applicable, check labels, record the results and return the system to its approved normal configuration.
What are common faults?
A circuit that does not respond to the selector position, a circuit that remains selected, a switch that is difficult to operate and an incorrect circuit being selected. Possible causes include incorrect wiring or terminal connection, faulty contacts, incorrect switch configuration, upstream or downstream faults, corrosion, contamination or mechanical wear. Do not force the selector mechanism.
Which standards apply?
References include FAA AC 150/5345-5B (L-847-1 to L-847-4), AC 150/5345-10H for the CCR interface, AC 150/5345-53D (certification program), ICAO Annex 14 Volume I, Doc 9157 Part 5 and IEC 61821, together with airport authority, DGCA and project specifications and manufacturer instructions.
Is it safe to work on a selector switch with the circuit energised?
No. Never open a live series circuit: an open series circuit driven by a constant-current regulator can produce dangerously high voltage. De-energise at the regulator, apply lock-out / tag-out, use the series circuit cut-out switch or approved isolation device, verify the circuit is de-energised and work under the permit-to-work system. See the electrical safety warning on this page.
What should I provide when requesting a circuit selector switch?
Provide the application, number of circuits, required switch positions, current and voltage rating, switching duty, contact arrangement, enclosure and mounting requirements, terminal and cable details, environmental conditions, the airport or project specification and the electrical schematic where available. For replacement, send existing switch details and photographs.
Procurement Information for Indian Projects
Indian public tenders commonly ask for the documents below. State which ones your tender requires when you send the enquiry, so they are covered in the quotation.
- Manufacturer / OEM authorisation
- Country of origin and local-content declaration (for Make in India purchase preference)
- Type-test and routine-test certificates, and the FAA / ICAO / IEC compliance documents named in the specification
- Datasheets, drawings and installation instructions
- Warranty, delivery period and spares support
- GeM catalogue or tender-portal requirements, where applicable
Request Circuit-Control Requirements Review
Need a circuit selector switch for an existing or new airfield lighting installation? Send us the number of circuits, voltage, current, switching requirement, existing switch details and circuit-control schematic where available, for technical selection support.
- Emailprecisionaglsolutions@gmail.com
- Websiterahulsharmaagl.in
- LinkedInPrecision AGL Solutions
- Phone+91 98214 96412
Engineering Note
A circuit selector switch should be treated as part of the complete AGL control and electrical system. Selection should consider the actual switching duty, circuit configuration, electrical ratings, contact arrangement, isolation requirements and interface with associated equipment such as the CCR.
For replacement projects, the existing switch configuration and approved electrical drawings should be verified before procurement.
Product Disclaimer
Product availability, configuration, dimensions, electrical characteristics, photometric performance, certifications and compliance status depend on the selected manufacturer and project specification. The technical values published on this page should not be treated as a substitute for the manufacturer's current approved Technical Data Sheet.
Final selection shall be based on the approved project specification, applicable aviation standards, authority requirements, manufacturer documentation and site conditions. Use of this page is also subject to the Legal Notice, Disclaimer & Terms of Use.
Standards and editions referenced on this site are listed on the Standards Reference page.