What are as-built records and circuit schedules?
The drawings and tables that show what was actually installed, circuit by circuit — checked against the site, kept current, and used for every later test and repair.
As-built records are the drawings and documents that show the AGL installation as it was actually built, not as it was designed. A circuit schedule goes with them: a table that lists, for each series circuit, the regulator, the cable, the lights and isolating transformers on it, and the values measured at commissioning.
Site conditions nearly always change something, so changes are marked up as they happen, checked against the ground and issued as revised drawings and schedules. Technicians then trace faults, check circuit load and choose spares from the records, and update them after every repair or change. Poor records mean the wrong cable traced, the wrong load assumed and slow fault finding.
- Mark up. Red-line the design drawings on site with every change: cable routes and depths, pit and equipment positions, and any substitution.
- Verify. Check the mark-ups against the installation: survey routes and pits, match cable tags to the drawing and confirm equipment details.
- Redraw. Update the drawings so they show the installed condition, using the same circuit and equipment references throughout, and issue a new revision.
- Schedule. Compile the circuit schedule: for each circuit, the regulator, cable, lights, transformers, pits and commissioning test values.
- Approve. Compare the drawings and schedules with the site and the design, resolve differences, then sign and date them.
- Hand over. File them in the asset register, linked to each asset, and issue controlled copies to the people who maintain the system.
Shows what was actually installed: the routes, positions and circuits as they exist on site.
Shows what was intended before construction. The two differ wherever site conditions forced a change.
Frequently Asked Questions
Q1What are as-built records in airfield ground lighting?
Drawings and documents that show the AGL installation as it was actually built, rather than as it was designed. They record cable routes and depths, handhole and pit positions, equipment locations, circuit references and any changes made on site, and they are the reference for every later inspection, test and repair.
Q2What is a circuit schedule?
A table that lists, circuit by circuit, what makes up each AGL series circuit: the regulator it is fed from, the cable type and length, the number and type of lights and isolating transformers, the pits it passes through and the values measured at commissioning. It lets a technician see a whole circuit on one line.
Q3How is an as-built drawing different from a design drawing?
A design drawing shows what was intended before construction. An as-built drawing shows what is actually in the ground and on the pavement. They differ wherever site conditions, obstructions or substitutions forced a change, which is why the as-built version, not the design, is the one used for fault tracing and maintenance.
Q4What information goes into a circuit schedule?
The circuit reference, the regulator and its rating, the lights and transformers connected with their ratings, the cable type, size and length, joints and pit references, earthing details, and commissioning results such as insulation resistance and the operating current. The exact fields are set by the project specification and the aerodrome's procedures.
Q5When should as-built records and schedules be updated?
First at the end of installation, when the red-line mark-ups are checked against the site and issued as the as-built set, then after every repair joint, re-route, replacement or upgrade. Each update carries a new revision and date, and the old version is kept as history rather than overwritten.
Q6Why do accurate as-built records matter for maintenance?
Technicians use them to find the right cable and pit, to check that a circuit's load is within its regulator's rating, to choose the correct spares and to compare test results with the baseline. Wrong records lead to the wrong cable being traced, slow fault finding and wrong assumptions about load. A record never replaces isolating and proving a circuit dead before work.
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