AGL Shallow Base for Elevated Airfield Lights

A shallow base is a lower-depth mounting arrangement for compatible elevated airfield lighting fixtures, used where available installation depth, pavement construction or site conditions favour a compact configuration. Configurations are selected for the fixture, mounting arrangement, cable requirements and project-specific installation conditions.

No. Shallow base is a commercial description, not an FAA type name. The FAA type reference for bases for elevated fixtures is L-867, while L-868 bases are for in-pavement fixtures, and each comes in classes and sizes, so state the type, class and size when ordering. The governing reference is FAA AC 150/5345-42K.

They are used with elevated runway and taxiway lighting fixtures, selected airfield visual-aid installations, replacement and rehabilitation projects, locations with restricted installation depth and installations where a compact base arrangement is required. Suitability should be confirmed against the selected fixture and the complete mounting arrangement.

Consider the available installation depth, pavement or foundation construction, fixture type and mounting geometry, mounting stem dimensions and cable-entry arrangement, the required mechanical support, drainage and environmental conditions, earthing and bonding as the project specification requires, and the existing installation dimensions for replacements. Fixture weight, height and mounting geometry, mechanical loading and the foundation construction also matter.

The arrangement may incorporate the elevated fixture, a mounting stem, a base plate, a frangible coupling and associated fixing hardware. Elevated lights in the movement area are expected to be frangible, so the base, stem and frangible coupling should be reviewed together, and the complete assembly checked for dimensional, mechanical and installation compatibility before field installation.

A deep base can often house the isolating transformer. With a shallow base the transformer is normally installed separately, for example in a transformer housing or junction arrangement, so confirm the transformer location during design.

Cable entry is part of base selection. The installation may need to accommodate primary or secondary cable, the fixture lead, the connector arrangement, cable routing, the transformer connection and location, and access for installation and maintenance. Confirm the cable dimensions and entry configuration with the selected base before ordering.

Check the existing installation details rather than assuming compatibility from the fixture name alone. Useful details are the existing fixture make and model, base dimensions, available installation depth, mounting stem dimensions, cable-entry arrangement, photographs or drawings, and pavement or foundation details. This helps determine whether a shallow base, deep base or alternative mounting arrangement is appropriate.

Verify the base dimensions and installation depth, the mounting interface and fixing arrangement, compatibility of the fixture and associated mounting components, the cable entry position, alignment requirements and mechanical stability. Final installation should follow the approved project design and applicable airfield-lighting requirements.

No. Never disconnect primary connectors or transformer connections while the series circuit is energised. De-energise at the CCR and follow the site lock-out procedure.

Applicable requirements depend on the fixture, mounting configuration and project specification. References include FAA AC 150/5345-42K (30 Sept 2024) on airport light bases, transformer housings, junction boxes and accessories, ICAO Annex 14 Vol. I on frangibility of visual aids and equipment, and ICAO Doc 9157 Part 6 on frangibility, together with the fixture documentation and project installation drawings.