What is base-can inspection?
A close look at the buried housing that holds an airfield light, checking the flange, grout, wall, drain and connector for water, corrosion, movement and damage before they become a fault. A base can hides most of its problems below the pavement.
A base can is the buried housing set in the pavement that holds an airfield light and the connector beneath it. It carries wheel loads, water, heat and frost year after year, and most of what goes wrong is out of sight. Water is the usual cause: it leads to connector and insulation faults and often points to a cracked grout joint, a failed seal or a blocked drain. A can that has moved or sits proud of the pavement is also a hazard to aircraft and vehicles. Inspection finds these early.
1Look at the surface first
Before anything is opened, check the fixture seating and the height of the can against the pavement. Look along the grout and pavement joint for cracks or gaps, check the bolts for corrosion, and note any standing water around the fixture. Work on the airfield only with the right permission and under the site’s safety rules.
2Make it safe, then look inside
Lifting the fixture disturbs the connector, so isolate and lock out the circuit and prove it dead, as your site procedure requires. A series circuit can carry a dangerous current and voltage, so treat the connector as live until it is proved dead. Lift the fixture out and keep debris from falling into the can. Note what you find before touching it: water, silt or debris, the state of the wall, flange and threads, the drain, the cable entries, and the connector and earth.
- Prove the circuit dead before lifting the fixture
- Cover the open can and keep debris out
- Photograph defects where they are
- Pack or shim a moved can
- Assume a dry surface means a dry can
- Leave a loose or cracked can in service
3Record and act
Photograph each defect and log it against its circuit and position. Inspection finds and records; cleaning, a new seal and reseating are base-can maintenance, and insulation and continuity tests prove the electrical condition. A can that is cracked, loose or at the wrong height is reported for corrective work to the design. Refit the fixture only as your procedure allows, and restore the circuit last.
| Check point | What to look for |
|---|---|
| Fixture seating | Seated flat, no rocking, nothing loose or missing |
| Height against pavement | Flush as designed; not proud of or below the surface, not tilted |
| Grout and pavement joint | Cracks, gaps, missing grout, breaking pavement edge |
| Flange, bolts and threads | Corrosion, damaged threads, missing or loose bolts |
| Can wall | Cracks, deformation, corrosion, signs the can has moved |
| Water and silt | Standing water, silt, debris, damp marks above the water line |
| Drain | Blocked or slow drain, silt in the outlet |
| Cable entries | Damaged or unsealed entries, chafed cable, gaps |
| Connector and earth | Wet, corroded or loose connector, including isolating-transformer connections where fitted; earth present and tight |
| Record | Dated photo, circuit and position, finding, action |
Frequently Asked Questions
Q1Why is a base can inspected?
A base can sits in the pavement for years, taking water, traffic loads, heat and frost. Water in the can is the usual cause of connector and insulation faults, and a cracked grout joint, blocked drain or loose can lets it in. Inspection finds these signs before the light fails.
Q2Can a base can be inspected with the circuit live?
Only from the surface. The surface can be looked at: fixture seating, height against the pavement, the grout and pavement joint, bolts and standing water. Lifting the fixture disturbs the connector, so the circuit is isolated, locked out and proved dead first, as the maintenance plan and site rules require, and the work is done under the airside permit.
Q3What defects should be looked for on a base can?
Look for standing water or silt inside, a blocked or slow drain, corrosion on the flange, bolts or threads, a cracked or missing grout joint, a can that has moved, tilted or sits proud of or below the pavement, a cracked wall, damaged cable entries, a loose or wet connector and a missing or loose earth connection.
Q4Is inspection the same as base-can maintenance?
No. Inspection finds and records the condition. Maintenance clears water and silt, fits a new seal, reseats the fixture and torques the bolts. A can that is cracked, loose or at the wrong height is reported for corrective work to the design, not packed or shimmed.
Q5What happens after a defect is found?
Photograph it, log it against the circuit and position, and raise the cleaning, repair or replacement. A can that is moved, cracked or standing proud of the pavement is raised promptly, because it is also a hazard to aircraft and vehicles.
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