What does a connector failure look like?
A joint that opens, overheats or lets water in — on the primary side it can take out the whole loop; on the secondary side, one light.
A connector failure is a fault in a connector or cable joint: the contacts, the insulated body or the seal. Connectors are made by hand on site, in pits and trenches, which makes them a common weak point. A joint fails in three ways: it opens, it develops a high-resistance contact that heats up or flickers, or it lets water in so that insulation resistance falls and an earth fault develops.
Where it fails decides how far it reaches. The primary connector carries the full loop current, so an open joint there breaks the loop for every light on the circuit. The secondary connector is on the isolated side and serves one fitting, so a fault there affects that light only. Never separate a primary connector on an energised circuit; a suspected failure is isolated, locked out and proved dead before any connector is touched. The secondary side is no safer to open live: an isolating transformer with its secondary opened can develop a hazardous voltage.
- Read the symptom. Whole circuit out or an open-circuit alarm, an earth-fault indication, or one fixture dark, dim or flickering.
- Check the pattern. A whole circuit or an earth fault points at the loop and its primary joints; one fixture points at its own secondary side, the fixture or the driver.
- Isolate. CCR off, locked out and tagged; prove the circuit dead.
- Look first. Open the can or pit and note water, silt and debris, then check each connector for a cracked or cut boot, corrosion, heat marks, a part-mated connector and strain on the cable.
- Test. With the circuit isolated, check continuity and resistance across the joint and insulation resistance to earth as the site procedure and commissioning record specify, and discharge the circuit after any insulation test.
- Replace and re-test. Cut back to sound, dry cable, fit the specified part, seal it as the maker instructs, test again and record the findings. Never reuse a damaged connector or seal.
On the loop, carrying the full current. An open joint breaks the loop for every light; a poor contact heats and can arc. See primary connector.
On the isolated secondary side, serving one fitting. A fault darkens, dims or flickers that light while the loop carries on. See secondary connector.
Frequently Asked Questions
Q1What is a connector failure in airfield lighting?
A fault in a connector or cable joint: the contacts, the insulated body or the seal. The joint can open, develop a high-resistance contact that heats up, or let water in so that insulation resistance falls and an earth fault develops.
Q2Why are connectors such a common weak point?
Cable is made in a factory, but connectors are made by hand on site, in pits and trenches where water is often present. A poorly mated contact, a damaged boot or a seal made on damp or dirty parts can fail later, which is why they are inspected and tested before the circuit is energised.
Q3What is the difference between a primary and a secondary connector failure?
The primary connector carries the full loop current, so an open joint there breaks the loop for every light on the circuit. The secondary connector is on the isolated secondary side and serves one fitting, so a fault there darkens, dims or flickers that one light while the loop carries on.
Q4What does a connector failure look like?
On the primary side, a whole circuit out, an open-circuit alarm at the CCR, an earth-fault indication or falling insulation resistance. On the secondary side, one fixture dark, dim or flickering. On inspection, a cracked or cut boot, corrosion, heat marks, a loose or part-mated connector, or water in the pit.
Q5What causes connectors to fail?
Moisture reaching the joint through a damaged or badly made seal, corrosion of the contacts, a loose or incompletely mated connection, heat from a high-resistance contact, strain on the cable at the joint, and mechanical damage to the moulding. Water and poor assembly are the common ones.
Q6Is it safe to disconnect a connector that may be faulty?
Only after the circuit is isolated, locked out and proved dead. Never separate a primary connector on an energised circuit, and never open a secondary connector on a live circuit either: an isolating transformer with an open secondary can develop a hazardous voltage. Treat every lead as live until the site's procedure says otherwise. Follow the permit-to-work and the manufacturer's instructions.
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