What is circuit zoning?
Splitting the airfield lighting into separate series circuits, each with its own CCR, so a fault, a dimming change or a shutdown stays inside one zone.
Circuit zoning is the division of the airfield lighting into separate series circuits, each normally fed by its own CCR and grouped by function and area: runway edge, runway centreline, threshold and end, approach, taxiway and stop bars. Each zone is its own closed loop.
Zoning lets each group be switched and dimmed independently, keeps every circuit within its CCR’s rating, and confines a fault to one circuit so the others stay in service. For critical elements, interleaving alternate fixtures across two circuits means losing one circuit thins the pattern instead of blacking it out, where the applicable standard requires it.
- Group. Divide the lighting by function and area into zones.
- Size. Keep each circuit’s load within its CCR rating, with spare capacity.
- Assign. Give each zone its own CCR and brightness steps.
- Interleave. Split critical elements across two circuits where required.
- Control. Switch and dim each zone separately from the control system.
- Record. Document the zone map so faults trace to a circuit quickly.
Frequently Asked Questions
Q1What is circuit zoning in airfield lighting?
Dividing the airfield lighting into separate series circuits, each normally fed by its own CCR and grouped by function and area, such as runway edge, runway centreline, approach lighting and taxiway lighting.
Q2Why is the lighting split into several circuits?
So each group can be switched and set to its own brightness independently, so every circuit stays within the rating and voltage limits of its CCR, and so a fault is confined to one circuit instead of taking out the whole airfield.
Q3How does zoning help with fault finding?
A fault is already narrowed to one circuit, and a shorter loop means fewer pits, connectors and transformers to split and test. The other circuits stay lit and in service while the faulted one is isolated and repaired.
Q4What is interleaving?
Feeding alternate fixtures in a lighting element from two different circuits. If one circuit is lost, every other light is still on, so the pattern is thinned rather than blacked out. Where it is required depends on the applicable standard and the category of the runway or approach.
Q5How are circuits sized?
Each circuit's total load, made up of the lamps or LEDs, the isolation transformers and the cable, must stay within the rating of the CCR serving it, with spare capacity for expansion. Sizing is done in the design calculations for the airfield.
Q6How are zoned circuits controlled?
Each circuit or group of circuits is switched and set to a brightness step from the control system, so for example runway edge, centreline and taxiway lighting can be selected and dimmed separately. Stop bars are commonly on circuits of their own so they can be selected independently.
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