What is pre-commissioning?
The static, de-energised checks made on a finished installation — proving the system is built, connected and recorded correctly before power is ever applied.
Pre-commissioning is the stage between installation and energisation. With the circuit de-energised and the CCR locked out, the installation is checked against the design: documents, workmanship, cables, earthing and equipment. Nothing is switched on, so faults are found with instruments rather than with live current.
Each check leaves a record. When every stage is complete, a hold point reviews the evidence: an open item is rectified and re-tested, and only a cleared hold point releases the system to energisation, the first live step of commissioning.
- Review. Check as-built drawings, schedules and the test plan are in hand.
- Inspect. Verify fixtures, alignment, seating, torque, labels and cleanliness.
- Test cables. Measure continuity and insulation resistance; check joints and connectors.
- Test earthing. Measure earth resistance and confirm bonding.
- Check equipment. Confirm CCR, control wiring and recorded settings.
- Sign off. Review records at the hold point; clear it or fix and re-test.
Frequently Asked Questions
Q1What is pre-commissioning in airfield ground lighting?
The set of static, de-energised checks and tests carried out on a completed installation before power is applied. It confirms the system is built as designed, safely connected and recorded, so that energisation can proceed.
Q2How is pre-commissioning different from commissioning?
Pre-commissioning is the first stage of the commissioning sequence and is done with the circuit dead: inspection, documentation review and electrical tests such as continuity and insulation resistance. The live stages begin at energisation and go on through functional testing, system integration, the ALCMS interface, PAPI and sign commissioning, and final acceptance.
Q3Why is pre-commissioning done de-energised?
A series lighting circuit carries a regulated current at high voltage, and a fault that would be found safely with test instruments on a dead circuit can become hazardous or damaging once the CCR is switched on. Finding wiring, insulation and earthing faults first protects people and equipment.
Q4What checks are normally included?
Review of as-built drawings and records, visual inspection of fixtures, alignment, seating and labelling, cable continuity and insulation resistance, joint and connector checks, earthing and bonding tests, and checks of the CCR, control wiring and settings. The exact list comes from the project specification and the applicable standard.
Q5What is the hold point before energisation?
A formal sign-off that every pre-commissioning check has been completed and recorded and that no open items would make energisation unsafe. Who witnesses and signs it depends on the contract, but energisation does not start until it is cleared.
Q6What happens if a check fails?
The item is logged as an open defect, rectified, and the failed check is repeated. The record shows the original result, the correction and the passing re-test, so the hold point is only cleared on evidence.
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