Where is the CCR located?
The constant current regulator (CCR) sits indoors, in the airfield lighting vault, not out beside the lights. From there each series circuit’s cable loops out across the airfield and returns to the same CCR.
A constant current regulator is installed indoors, in the airfield lighting vault, also called the AGL electrical equipment room or substation. It is placed on the airside edge of the airfield, usually near the apron or control tower, and never on the runway or taxiway. The CCR does not sit next to the lights it feeds. Instead, the primary cable of its series circuit leaves the vault, runs through the isolation transformer at each light and returns to the same CCR, so the loop starts and ends at the vault.
The vault position is a balance. It should be close to the incoming utility supply and standby source, within reach of the control tower link, easy to reach by road and kept dry, cool and ventilated. It is sited outside the runway strip and clear of ILS critical areas and the obstacle limitation surfaces. Because the CCR must supply the whole series load, including the cable losses, very long loops are avoided; larger airfields often use a central vault plus remote vaults or shelters to keep the runs short. Treat any series circuit as live until the CCR has been isolated and locked out under site procedures.
Frequently Asked Questions
Q1Where is the CCR located at an airport?
A constant current regulator (CCR) is normally installed indoors, in the airfield lighting vault (also called the AGL electrical equipment room or substation). The vault sits on the airside edge of the airfield, usually near the apron or control tower, and not on the runway or taxiway itself.
Q2Why is the CCR not next to each light?
In a series circuit one CCR drives every light on the loop through its isolation transformer. The CCR is therefore central equipment, kept in a dry, ventilated, accessible building, while only the cable and the transformers go out onto the airfield.
Q3How far can the vault be from the lights?
There is no single fixed distance. The limit is the CCR rating: its output must cover the total series load, which includes the transformers, the lamps or LED loads and the losses in the primary cable. Long loops add cable losses, so large airfields often add a second vault to shorten the runs.
Q4Why must the vault stay clear of ILS critical areas?
Large structures and vehicles close to the localizer or glide path can disturb the ILS signal, and tall structures can penetrate the obstacle limitation surfaces. Vault sites are checked against both before the building is placed.
Q5Does an airport need more than one vault?
Many airports use one central vault. Larger airfields, or those with widely separated runways or remote approach lighting, may add remote vaults or shelters, each with its own CCRs, so that cable runs and voltage losses stay within the CCR ratings.
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