What is water ingress prevention?
Keeping water out of the structures that hold airfield lighting, with shed surface water, sealed joints, gasketed covers and sealed entries, so cables, connectors and transformers stay dry.
Water ingress prevention is the set of measures that keep water out of base cans, transformer pits, handholes and cable ducts. It normally means surface falls that shed water away from covers, sealed joints between the structure and the pavement, gasketed covers, and sealed duct and cable entries, all as the design shows.
It is a civil interface because most of the entry points are made by the civil works: the pavement joint around a can, the falls around a cover and the duct entries through pit and handhole walls. Agree these details with the civil designer and check them before they are covered. Water can also run along a duct or trench from a wet or low point, so seal the duct entry and the duct end, using seals that can be re-opened for cable work. Water inside a structure lowers insulation resistance and can cause corrosion and earth faults on the series circuit. Seals are never perfect, so pair prevention with drainage. Treat any cable as live until it has been isolated, locked out and proved dead, and work to the airport’s permit-to-work.
Keeps water out: falls, sealed joints, gasketed covers and sealed entries.
Leads away the water that still gets in, to an approved outlet.
Frequently Asked Questions
Q1What is water ingress prevention in airfield ground lighting?
The set of measures that keep water out of the structures that hold airfield lighting, such as base cans, transformer pits, handholes and cable ducts. It normally means falls that shed surface water away from covers, sealed joints between the structure and the pavement, gasketed covers, and sealed cable and duct entries, all as the design shows.
Q2Why is water ingress prevention a civil interface?
Most of the entry points are made by the civil works: the pavement joint around a can, the falls around a cover, and the duct entries through pit and handhole walls. The AGL team has to agree these details with the civil designer and check them before the work is covered.
Q3How does water get into an AGL structure?
Surface water can pass a worn cover seat, a damaged gasket or a cracked, lifted joint sealant. Groundwater can pass an unsealed duct or cable entry. Water can also travel along a cable duct or trench backfill from a wet or low point, and through damaged cable jackets or poorly sealed connectors.
Q4Why seal duct entries and duct ends?
A duct can carry water from a wet trench or low point straight into a pit or can. A seal where the duct meets the wall, and a seal around the cable at the duct end, close that path. Use seals that can be re-opened, so cables can still be pulled or replaced.
Q5What is the difference between ingress prevention and drainage?
Prevention keeps water out in the first place. Drainage leads away the water that still gets in. Seals are never perfect, so a good design uses both, and neither replaces the other.
Q6How is water ingress prevented in service?
Look for cracked or lifted sealant, damaged gaskets, ponding near covers, water marks and corrosion. A falling insulation-resistance trend on a circuit can also point to water. Re-seal with approved materials after any disturbance, such as pavement repairs or a can change, and re-check afterwards.
Q7Where are the requirements defined?
FAA AC 150/5340-30 covers design and installation of airport visual aids, AC 150/5370-10 (standard specifications for construction of airports) includes the pavement joint sealant specification, and ICAO Doc 9157 Part 5 covers electrical systems. Confirm against the current edition, the design drawings and the manufacturer's data.
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