Most of us are familiar with the standard plastic mounting spike that’s included with landscape lighting fixtures. That spike is designed to hold the fixture vertical and keep the metal from touching the ground, avoiding corrosion and damage to the stem.
Soil type and weather need to be considered in determining the correct type of ground mount, as sometimes a traditional spike is not enough to provide a proper, secure mounting.
I’ve spoken to several contractors across the country to get their input on choosing the right ground mount for the job. Let me share a few kinds of ground-mounting systems with you to help you make the best choice for the area you live in.
Brass ground spikes. These can provide hearty mounts in areas with hard ground. Depending on the soil density, a brass spike can be pounded into the ground with a dead-blow hammer. It has been said that a solid brass spike can also assist as an additional ground should there be any crossover voltage from a faulty transformer. Over time, they’ll acquire an attractive patina just as brass fixtures do. Contractors in the Northeast primarily rely on solid brass spikes, as they perform well in freezing conditions and in very wet locations.
Post and cap mounts. These are primarily used in line-voltage applications. They usually consist of a plastic or metal cap with a ½-inch conduit thread and a ¾-inch, angle-cut ABS stem. Stabilizing bars are often included. The bars assemble like a grid with the stem in the center and assist in keeping the post and cap level. There are occasions where it will be necessary to mount an adjustable or path light in a turf area. When this is required, the post and cap is a good mounting choice, because it will keep the fixture out of the way of mower wheels and trimmer strings.
When performing monument lighting, this style will work very well. If the location is susceptible to vandalism, it may be necessary to set it in concrete. Some manufacturers offer these mounts in a telescopic style, which works very well in areas where plant material could grow over the fixtures. Architects will specify this mounting system for the majority of commercial 12-volt applications.
Tri-spike mounts. These are a relatively new style of mounting system, normally constructed out of stainless steel or brass, with a thick, flat, round thread and three long, nail-like spikes protruding from the bottom (hence the name). Tri-spike mounts are an excellent choice for any soil type. Loose soil is a challenge for most mounting systems, but the tri-spike meets it very well.
To install them, one contractor I spoke with creates a concrete pour tube with a 1-foot piece of 4-inch-diameter low-head drain pipe. Upon leveling the concrete, he inserts the tri-spike mount into the pipe. Enough clearance is left to slide the fixture’s lead wire through. This method is often used in commercial and high-end residential projects.
Underground box mounts. These are like direct-bury transformers without a transformer inside. These mounting systems are generally used in commercial applications where conduit is required. It’s a common specification if more than one fixture is needed in an enclosed area.
The underground box mount is made from cast brass or glass-filled composite material. The lid can be manufactured with multiple outlets that will accept fixture threads. A watertight gasket keeps the cable connections dry.
Using the correct tool for the job is a standard in the landscape lighting business. All the major manufacturers are equipped to help you with great ground-mounting systems. In our next article, we’ll take a good look at tree- and wall-mount devices. Until then … choose wisely!
Kevin Smith is the national technical support and trainer at Brilliance LED LLC, Carefree, Arizona, and can be reached at firstname.lastname@example.org.