What is a cable gland?
A fitting where a cable enters the housing, gripping the cable and sealing around it to keep water out.
A cable gland is a fitting that holds a cable where it passes through the wall of a housing. It grips the cable so it cannot be pulled out, and its seal closes around the cable sheath so water and dust cannot follow the cable in.
1Three parts, one job
The body is fixed through the housing wall. A seal insert sits inside it, around the cable. A compression nut squeezes the seal, which presses against the sheath to close the gap and hold the cable.
2It protects the joints as well as the seal
A cable that is pulled or bent hard at the entry puts strain on the connections inside. The gland takes that load at the wall, so the joints are not the weak point. Not every fixture has one: many use a secondary lead with a moulded connector instead.
3Right size, right tightness, sound seal
The usual faults are the wrong size, a nut tightened wrongly, a perished seal, and strain at the entry. Check the gland suits the cable, tighten the nut only as the manufacturer specifies, and replace a damaged gland only with the type specified. A fixture is opened only with its series circuit isolated, locked out and proved dead.
| Part | What it does | Main risk |
|---|---|---|
| Body | Fixes the gland through the wall | A loose body leaks at the wall |
| Seal | Closes around the cable sheath | Wrong size or aged seal leaks |
| Nut | Squeezes the seal onto the cable | Too loose slips; too tight crushes |
| Cable entry | Takes pull and bend at the wall | Strain damages cable or joints |
Frequently Asked Questions
Q1What is a cable gland in an airfield light fixture?
A cable gland is a fitting that holds a cable where it passes through the wall of a housing. It grips the cable so it cannot be pulled out, and its seal closes around the cable sheath so water and dust cannot follow the cable in.
Q2How does a cable gland seal and grip the cable?
The gland body is fixed through the housing wall. A seal insert sits inside it around the cable, and a compression nut squeezes that seal. The squeeze presses the seal against the cable sheath to close the gap, and the same pressure holds the cable in place.
Q3Do all airfield light fixtures use a cable gland?
No. Many fixtures take their power through a secondary lead with a moulded connector instead, so there is no gland on the cable. A gland is used where a loose cable passes into a housing, so check the product design.
Q4What happens when a gland is the wrong size, badly tightened or damaged?
A gland that does not suit the cable cannot close evenly around the sheath. A nut that is too loose lets water in and lets the cable slip, and one that is too tight can crush the cable. A cracked or aged seal also leaks. Water that gets in can reach the connections and optics.
Q5How should a cable gland be checked or replaced?
Only with the series circuit isolated, locked out and proved dead, and only as the manufacturer's instructions allow. Check that the gland suits the cable, that the nut is tightened as specified, that the seal is not cracked or perished, and that the cable is not being pulled or bent hard at the entry. Replace a damaged gland only with the type the manufacturer specifies.
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