What is internal wiring?
The short, heat-resistant wires inside the fixture head. They carry power from the entry connector to the driver and the light source, and must stay secured, sealed and clear of hot parts.
Inside every fixture head, power has to reach the electronics and the light source. The internal wiring is the short run of wire that does it.
1It links the parts
Wires run from the entry connector or lead to the driver, and from the driver to the LED module or lamp holder. In a lamp fixture the wiring is simpler; in an LED fixture it may also carry control or sensing signals. The layout is set by the manufacturer.
2It has to survive the head
The head is hot, vibrates with aircraft and traffic, and may take in moisture. The wires use heat-resistant, flexible insulation, are held by clamps and strain relief, and are routed away from hot parts and sharp edges so nothing chafes or is pinched when the cover goes on.
3Check it, and refit it as found
Look for brittle or discoloured insulation, loose terminals, chafing, pinched wires, water marks and wires touching hot parts. Replace damaged wiring with the correct manufacturer part and refit it in the original routing, with terminals tightened as specified.
| Element | Detail |
|---|---|
| Internal wiring | Short fixed wires inside the fixture head |
| Runs between | Entry connector or lead, driver, and lamp holder or LED module |
| Insulation | Heat-resistant, flexible, rated for the fixture environment |
| Securing | Clamps, strain relief and secured terminals |
| Routing | Clear of hot parts, sharp edges and moving covers |
| Reference | Manufacturer instructions; FAA AC 150/5345-46 (light fixtures) |
| Check | Insulation condition, terminal tightness, chafing, water, original routing |
Frequently Asked Questions
Q1What is the internal wiring of an airfield light?
The short insulated wires inside the fixture head that connect the incoming connector or lead to the driver, lamp holder or LED module.
Q2How is internal wiring different from the secondary lead?
The secondary lead is the cable from the isolating transformer up to the fixture. Internal wiring is the fixed wiring inside the head. In some products the lead ends at a connector and internal wiring carries on from there; in others the lead runs straight to the light source.
Q3What should be checked on internal wiring?
Check for brittle or discoloured insulation, loose terminals, chafing, pinching under covers, signs of water, and wires touching hot parts. Replace damaged wiring with the manufacturer part and refit it in the original routing, then reseal the fixture and test the circuit as the manufacturer and site procedures require.
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