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Project Difficulty:
Moderate
Estimated
Project Time: A few days
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Lamppost and light fixture
Measuring tape
Shovel
Posthole digger
Awl
Hacksaw with blade-type grip
File
Rigid metal conduit
Plastic bushings
THHN/THWN wire for use in conduit (or UF cabling for ground contact)
Fish tape
Wire connectors
Plastic electrical tape
Concrete (or dirt mixed with gravel)
Trowel
2x4
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Having a lamppost in your yard can add character to your home and provide an extra bit of security. You can add one of these lampposts to your home as part of a weekend project. Before you run out and buy a lamppost, however, there are a few things you'll need to do.
First, check your local building codes to make sure that installing a lamppost in your yard is permissible. You should check for any height restrictions and see how far away from the road you have to stay. You will also need to determine how deep the lamppost will need to be set into the ground, based on its height and weight. For good stability, the post should be set at least 2 feet below ground level. Homeowners in areas that are susceptible to cold weather should set the post far enough below ground level that it won't be affected by frost heaves. The post can also be anchored to a footing below the frost line.
If using wire that should not come in contact with the ground, you will need to pass it through conduit in order to keep the wire dry and avoid shortouts and shocks. UF cable, however, can be buried without passing it through conduit, but it cannot come in contact with cement. So, if you intend to set the lamppost in concrete, you will need to pass the UF cable through a length of conduit where the concrete will be and then allow for expansion by making loops in the cable as shown in Figure 1.
The instructions below are for installing a lamppost that is wired through metal conduit. Before starting to work, determine where the post will be and how to get electrical power to it. If tapping into an existing electrical circuit make sure it can handle the increased load; if creating a new circuit, plan to run the wires to the main electrical service panel. Install the post, as explained below, but before connecting the electrical line to the house power, turn off power to that circuit.
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1.
Dig the Hole for the Lamppost
Using a posthole digger, dig a hole at least 2 feet deep and 8 inches wide for the lamppost. Then, if you are using a rigid metal conduit, use a shovel to dig a 6-inch-deep trench from the posthole to the place where you'll be connecting your wire. If you're using UF cable instead of wire and a conduit, dig the trench at least 2 feet deep to protect the cable.
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2.
Prepare Post for Conduit
In order for the base of the lamppost to accept the conduit, enlarge the opening in the side of the post. First, use an awl to scribe two parallel lines, 18 inches long and about 1 inch apart (Fig. 2). Then, using a hacksaw with a blade-type grip, cut along both lines. Bend the cut strip back until it is perpendicular to the post, and then saw it off. Use a file to smooth out any sharp edges. (If you'll be running a wire to the post and then to an additional fixture, form another slot in the side where that wire will exit.)
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3.
Cut the Conduit
Measure the distance from top of the lamppost down through its trunk and out to where the wire or cable will connect to your house; then cut a length of rigid conduit to equal that measurement. If you're installing an adjustable lamppost, you'll need to run the conduit up to only the lock ring on the post, as shown in Figure 3, below.
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4.
Connect the Conduit
Fasten the conduit to the lamppost and then to the connector on the house. Before connecting the conduit, cap both ends with a plastic bushing to prevent any sharp edges in the conduit from damaging the wire.
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5.
Connect Wire/Cable to Light Fixture
Using a fish tape, pull the wires/cable through the conduit, up through the post, and connect them to the lamppost's light fixture. All wires, even single-strand wires that are pulled through the conduit must be insulated. If the wire is white it must be the neutral wire; other wires may be black or red. Splice similar coded wires together, using wire connectors to connect them. Then wrap plastic electrical tape around the connections. Install the light fixture to the top of the lamppost.
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6.
Set the Lamppost into the Ground
The preferable method is to set the post into the ground using concrete to hold it in place. One bag of ready-mix concrete will make about two-thirds of a cubic foot of concrete (follow package instructions). You will need two to four 80-pound bags of concrete for sound footing. Drop the lamppost into the hole, use a level to make sure it's plumb, and then, holding it straight, pour in the concrete mix. (You might need a helper.) Use a trowel to slope the top of the concrete away from the lamppost down toward the ground so that water will drain away from the post. Use a 2x4 to brace the lamppost until the concrete hardens. After two days, the concrete should be able to fully support the post. Fill in the rest of the hole and the trench.
As an alternative to concrete, you can fill the posthole with layers of dirt mixed with gravel. Use a 2x4 to compact each layer of dirt and gravel as you add them. (Fig. 3)
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7.
Connect Lamppost to Electric Power
If you're installing a new electrical circuit for the lamppost, run the wiring to the main electrical service panel. Be certain the power is turned off at the service panel before working on the circuit. Connect the power hook-up. Turn the power back on, and then turn on the light. You'll be the envy of the neighborhood!
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