What is an approach-light foundation?
The buried concrete base that holds a stem or mast upright, with its top level with the ground and a frangible coupling just above it.
Every approach-light stem or mast stands on a foundation, usually cast concrete buried in the ground. Anchor bolts set in the concrete hold the base plate, and the frangible coupling sits just above it, so the structure breaks away cleanly from a base that stays put.
The top of the foundation is kept flush with the finished ground so it does not become a solid obstacle. A duct runs from the transformer can to the stem base, and the secondary lead goes through it. A tall mast needs a larger footing than a short stem, sized for its height, loads and the soil.
Frequently Asked Questions
Q1What is an approach-light foundation?
It is the buried base, usually cast concrete, that holds an approach-light stem or mast upright. Anchor bolts in the foundation carry the frangible coupling and the structure above it.
Q2Where should the top of the foundation be?
Flush with the finished ground, so the foundation itself is not a solid object standing in the approach area. The frangible coupling sits just above it.
Q3How is the foundation sized?
By the height and weight of the structure, the wind and other loads on it, and the soil. A short stem needs a small footing; a tall mast needs a larger one designed for the job.
Q4How does the cable reach the light?
A duct runs from the transformer can to the base of the stem. The secondary lead is pulled through it and up the stem to the lamp.
Q5Why are anchor bolts set from a template?
A template holds the bolts at the exact spacing of the coupling plate while the concrete sets, so the structure stands upright and sits flat on the foundation.
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