The Complete Handbook of In-Ground Lights

Chapter 1: Understanding In-Ground Lights

An in-ground light is a luminaire designed to be installed at or below the surrounding finished grade, so that its light-emitting surface is flush with the walking surface, driveway, or planting bed. The concept is simple, but it is one of the hardest working categories in all of lighting. Unlike a wall sconce bolted to an interior wall, or a streetlight mounted ten meters in the air, an in-ground fixture is subjected to a uniquely hostile environment that combines moisture, dirt, weight, temperature extremes, and foot or vehicle traffic.

To understand what an in-ground light is, you need to understand the physical reality of where it lives. It is buried. It is surrounded by soil, which holds water and chemicals. It is covered by a lens that people walk on, drive on, or pile mulch and leaves on top of. It is expected to produce a useful amount of light for years, despite the fact that the components inside are constantly fighting a battle against water ingress and heat buildup. The fact that these fixtures work at all is a testament to engineering, and the fact that they fail is almost always due to a fundamental misunderstanding of these environmental pressures, not a random defect.

Consider the standard application of an in-ground well light, perhaps used to uplight a specimen tree or a stone wall. The fixture sits in a hole that is dug in the ground, often at the base of a planting bed.