What is a cable entry?
Where an AGL cable passes through the wall of a base can, pit or housing — formed at the designed position, with smooth bushed edges, a gentle bend, a seal around the cable and a slack loop inside, so the enclosure stays dry and the sheath is not cut.
A cable entry is the point where an AGL cable passes through the wall of a base can, pit, sign or equipment housing. It is formed at the position the design provides, with smooth, bushed edges, and sealed around the cable so the enclosure stays dry and the cable is protected where it crosses from the ground into the enclosure.
The entry is a small detail with a long life. A sharp edge slowly cuts the sheath, and an open or poorly sealed entry lets in water, soil and pests that end up around connectors and terminations as earth faults. Bring the cable in with a gentle bend, leave a slack loop inside, blank off any unused entry and identify the cable. Treat any cable as live until the circuit has been isolated, locked out and proved dead, and work to the airport’s permit-to-work.
- Position. Use the entry the design provides and bring the duct in line with it.
- Open. Form the opening or sleeve cleanly and smooth any cut edges.
- Bush. Fit the bush, grommet or gland so the sheath has a smooth path.
- Pull. Bring the cable through without strain and keep to its minimum bending radius.
- Seal. Seal around the cable as specified and blank off unused entries.
- Slack, mark and record. Leave a gentle slack loop, identify the cable and record the entry.
Frequently Asked Questions
Q1What is a cable entry in airfield ground lighting?
A cable entry is the point where an AGL cable passes through the wall of a base can, pit, sign or equipment housing. It is formed at the position the design provides, with smooth edges, and sealed around the cable so the cable is protected where it crosses from the ground into the enclosure.
Q2Why does a cable entry have to be sealed?
An open entry lets water, soil and dirt run into the pit or base can, and can give rodents and insects a way in. Water around connectors and terminations is a common cause of insulation faults. The seal keeps the enclosure dry and clean, and the method and material are set by the design and the manufacturer.
Q3Why must the edges of the entry be smooth or bushed?
The cable sheath is pulled or pushed past the edge of the opening and then sits against it for years. A rough or sharp edge can cut or wear the sheath, which later shows up as an earth fault. A bush, grommet or gland gives the cable a smooth, supported path through the wall.
Q4Why leave slack in the cable just inside the entry?
Slack, usually as a gentle loop, lets the cable move with ground settlement and temperature without pulling on the entry or the connector, and leaves enough length to re-terminate or replace a fixture later. The loop must stay within the cable’s minimum bending radius.
Q5What should be done with unused entries?
Unused entries are blanked or plugged as the design and manufacturer specify, so they do not become a route for water or pests. Do not leave a knock-out or sleeve open, and do not make a new opening in a pit or base can except as the design allows.
Q6What should be checked before the entry is covered or the pit closed?
Check that the entry is at the designed position, the edges are smooth or bushed, the cable has a gentle bend and is not strained, the seal is complete around the cable, unused entries are blanked, slack is left inside and the cable is identified. Treat any cable as live until the circuit has been isolated, locked out and proved dead, and work to the permit-to-work.
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