What is the installation sequence?
The order in which AGL works are built — set out, ground works, cables and earth, equipment, alignment, then test — with each stage checked before it is covered, because most of it ends up buried.
The installation sequence is the order in which AGL works are built: set out, ground works, cables and earth, equipment and connections, alignment, then test and record. Each stage rests on the one before it, and most of the work — base cans, ducts, cables and earthing — ends up under backfill or pavement, so it is checked before it is covered.
A base can in the wrong place or a cable laid before its duct is checked can only be put right by digging up finished work. Fix the layout before anything is dug, stop at each hold point until the work is inspected and released, and fit and align the fixtures late, once the base is stable and other trades have moved on. See Installation Quality Checkpoints for what is checked at each point, Construction Sequence for the civil works around it and Commissioning Sequence for what follows. Work under the airport’s permit-to-work, check cable locations before excavating, and treat any circuit as live until it has been isolated, locked out and proved dead.
- Set out. Mark positions, lines and levels from survey control and the issued drawings, and fix the layout before digging.
- Ground works. Excavate after cable locations are checked, lay ducts, set base cans and foundations to position and level, then hold for inspection before backfill.
- Cables and earth. Lay and identify the cable, and lay the bare earth conductor as specified (normally above the cable), with the specified protection and slack. Test the cable, then hold for inspection before covering.
- Equipment and connections. Fit transformers, connectors, fixtures, signs and PAPI units, make and seal the connections, and bond the metalwork.
- Align and secure. Set each unit’s position, height and aim as designed and tighten to the specified torque.
- Test and record. Prove continuity and insulation resistance of the completed circuit, record the results and as-built drawings, then hold before energising and handover.
Frequently Asked Questions
Q1What is the installation sequence in AGL construction?
The order in which the AGL works are built: set out the layout, do the ground works, lay the cables and earth, fit the equipment and make the connections, align and secure each unit, then test and record. Each stage rests on the one before, and the work is checked at set points before it is covered.
Q2Why does the order matter?
Much of an AGL installation ends up under backfill, concrete or pavement, and each stage depends on the last. A base can set in the wrong place or a cable laid before the duct is checked can only be put right by digging up finished work. Working in the right order, and checking before covering, keeps that rework to a minimum.
Q3What is a hold point?
A point where work stops until the work done so far has been inspected and released. The usual hold points are before backfilling the bases, ducts and cable trench, before covering cables and earth, and before the circuit is energised. The specification and the inspector set the exact ones for each project.
Q4Why are fixtures fitted and aligned late in the sequence?
A fixture can be damaged by other trades working around it, and its aim depends on a finished and stable base can or foundation. Fitting and aligning it once the ground works and cables are done protects it and means the alignment is made once, against a base that will not move.
Q5How is this different from the construction sequence and the approach-light installation sequence?
The construction sequence covers the order of the civil and AGL works together, including paving and the hold points around it. The approach-light installation sequence covers the build of one system. This entry covers the order of the AGL installation work itself, which any of these projects follow.
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