Halogen-to-LED migration sequence
Six stages, one circuit at a time. Each stage has a check to pass before the next begins, and a failed check sends the work back to design, not forward to handover.
Moving from halogen to LED is a sequence of stages, not a lamp swap. The order matters because the load match has to be designed before equipment is bought, and proved before a circuit is accepted. Skipping ahead is how a retrofit ends with a CCR running far below its range, or lights that do not meet their brightness steps.
Each stage ends at a gate. Passing the gate lets the work move on. Failing it, most often at commissioning, sends the work back to design, not forward to handover.
One type of fixture per circuit. The load is matched once, the whole loop behaves the same way, and only one isolated circuit is in work at a time.
Halogen and LED on one loop, for a time, only with each lighting system kept to one technology. The load, the brightness behaviour and the CCR response all differ, so it needs its own design and checks.
| Stage | What is done | Gate before moving on | Record |
|---|---|---|---|
| 1 · Survey | List fixtures, transformers and CCRs; measure the present load and series current | The starting load is known and checked | Baseline load per circuit |
| 2 · Design | Compare the new load with the CCR and transformers; decide what to keep, change or add | CCR and transformers suit the new load | Load-match design |
| 3 · Procure and test | Buy approved fixtures; test a sample before the main order | Sample passes the electrical and photometric checks | Test results |
| 4 · Install | Isolate and prove one circuit dead, replace the fixtures and fit any changed equipment | Circuit proved dead before work; work checked before re-energising | Installation record |
| 5 · Commission | Measure current at each step, the load, the CCR behaviour and the light output | Meets the requirement at every step | Commissioning results |
| 6 · Hand over | Update records and spares; brief maintenance staff | Records match what is installed | As-built drawings and schedules |
What to plan around the sequence
Airport operations
Agree each isolation with operations, and plan which lights stay available while a circuit is out.
Way back
Decide beforehand how a circuit is restored if it fails a check, so a problem does not leave it out of service.
Spares
Change the spares list to match the new fixtures, and keep halogen spares only for systems not yet converted. Under FAA AC 150/5340-30 (para 1.4), a failed halogen fixture is replaced like for like, not by an LED fixture. Confirm which rule your national regulator applies.
Training
Brief maintenance staff on LED fixtures, drivers and the new test readings before the first circuit goes live.
Removed lamps
Dispose of removed halogen lamps and any replaced equipment under the site’s rules.
Records
Update the drawings and schedules as each circuit is finished, not only at the very end.
Frequently Asked Questions
Q1What is the halogen-to-LED migration sequence?
It is the order of work for moving a lighting system from halogen to LED: survey the existing circuits, design the load match, procure and test the equipment, install circuit by circuit, commission and verify, then hand over with updated records. Each stage has a check that must be passed before the next begins.
Q2Why survey before choosing LED fixtures?
The survey fixes the starting point: the fixtures, the isolation transformers, the CCR, the present circuit load and the series current. Without those figures the new load cannot be compared with what the equipment was sized for, so the load match cannot be designed.
Q3Why convert one circuit at a time?
A circuit is a single series loop with one CCR, so converting it in one go means the load is matched once and the whole loop behaves the same way. It also keeps the work to one isolated circuit at a time, which is easier to plan and to restore if a problem appears.
Q4What if a circuit has to carry both halogen and LED fixtures for a while?
A mixed circuit is possible only where each lighting system on it stays a single technology, and it is a design decision of its own, because the load, the brightness behaviour and the CCR response all differ from a single-type circuit. FAA AC 150/5340-30 (para 1.4) does not allow LED and incandescent fixtures of the same type to be interspersed, so convert each lighting system as a whole, and confirm whether your national regulator applies the same rule. It should be planned and checked, not left as an accident of the work order.
Q5What is checked at commissioning?
The series current at each brightness step, the circuit load and the CCR behaviour, the light output against the requirement, and that monitoring and alarms still work. A circuit that fails a check goes back to the design stage instead of being accepted.
Q6What records should be updated at the end?
The equipment schedule, the new load figures for the circuit and the CCR, the transformer ratings, the spares list and the as-built drawings. The next change then starts from the right numbers, and staff are told what changed.
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