See your way to a safer terrain with this step-by-step guide to installing a lamppost.
Let there be light – at least enough for people to see what treacherous terrain might lie underfoot as they approach your home. Illuminate the topography with a lamppost, which will light the way for weary travelers and homebound housemates alike. Installing one is simpler than you might think. A hole filled with concrete keeps the post straight, and a narrow trench from the house carries the wiring – you could do that all in a day, as This Old House technical editor Mark Powers shows here.
Hooking up the wiring to the main box and adding a switch – for that, you should hire a licensed electrician, but there’s no reason you can’t install the post and run the wiring yourself. There’s even some added satisfaction for your effort: Your guests will thank you for your hospitality that much more when they can actually see their way to your front door.
Step 1: Lamppost Overview
You don’t want a lamp that leans like a prizefighter in the 12th round—it must stand tall and straight. Unfortunately, the ground won’t always cooperate in supporting the post because rains and frosts and even droughts can shift the soil. So you need to set it in a stable footing to keep it aligned. About 16 inches of concrete will do the trick, with the post set 12 inches into it. You can also add to the stability of the lamp by digging a deeper hole and lining it with about 6 inches of gravel, says This Old House general contractor Tom Silva. Though manufacturers don’t require this step, Tom recommends it to help with drainage and minimize frost heaves in colder climates.
To bring the wiring from the breaker box in the house out to the post, you’ll need to bury it. The wire we recommend you use is rated for direct burial, but in concrete, it needs the protection of PVC conduit. For a double measure of safety, we suggest you protect the wire with conduit for its entire run. That will avoid any nasty surprises should someone dig too close later on. The lamp post is hollow to allow the wires to run without the conduit from the base to the lantern top.
When you run the wire, make sure to leave plenty of extra near the house so there’s enough to snake through the wall and reach the circuit-breaker panel inside the house. Then have a licensed electrician check your work, make the connection to the breaker, and install the switch for the light.
Step 2: Dig the posthole
Using a posthole digger or round shovel, make a hole at the post location 12 inches in diameter and 22 inches deep. Fill the bottom of the posthole with 6 inches of gravel. Then, use a trenching spade to create a narrow, 18-inch-deep
Step 3: Form the trench
When digging the posthole and trench, place the soil on top of a plastic tarp. That way, you won’t bury the surrounding grass or plants, and the tarp will make it a whole lot easier to scrape the soil back into the hole and trench when it comes time to backfill.
Step 4: Install the PVC conduit
Dry fit PVC conduit to reach from the house to the posthole. Where necessary, cut the pieces with a hacksaw. Attach elbows to bring the conduit away from the house and down into the trench, then up from the trench at the post. Add conduit to the elbow in the post¬hole long enough to protrude 6 inches above the ground.
Connect the conduit pieces with PVC cement, making sure that all the elbows are oriented correctly. Next, thread 12-gauge UF-rated wire through the pipe. Leave 9 feet extra at the post location and enough extra at the house to reach through the walls and to the breaker box. Lay the pipe, with the wiring inside, in the trench, then backfill with soil.
Step 5: Fill the posthole with concrete
Mix a batch of concrete in a trough or wheelbarrow, one bag at a time. Keep the mix stiff (not too much water) to help support the post and shorten the set time. The concrete should hold its shape, but jiggle a little when jostled.
Shovel the concrete into the posthole atop the gravel, being careful not to get any into the conduit or on the wires. Fill the hole to grade or just below it, leaving about 6 inches of conduit exposed. Using a concrete float or a piece of scrap wood, smooth the top of the footing.
Tip: Use your shovel to chop gently at the concrete as you fill the hole, which will help eliminate air pockets.
Step 6: Set the post into the concrete footing
Working carefully but quickly, lay the post next to the hole and pull the wires through it from bottom to top. With the concrete still wet, slide the shaft of the post over the conduit and 12 inches into the concrete, making sure the wires still protrude from the top of the post. Twist the post as you put downward pressure on it to work it into the concrete.
Tip: Before setting the post, mark it with a pencil 12 inches up from its bottom so you’ll know how deep to plant it in the concrete.
Step 7: Install the lamppost
Wrap two or three straps or ropes around the post and stake them into the ground a few feet away, which will brace the post by pulling it in opposing directions. Hold a level vertically against the post in several spots around its circumference to check it for plumb.
Step 8: Brace lamppost perfectly plumb
Adjust the straps attached to the lamppost, as necessary, to securely hold the post in position. Allow the concrete to harden completely before removing the straps—at least four hours.
Step 9: Make the wire connections
Once the concrete is hard enough to hold the post without straps, use a utility knife to carefully peel away 3 inches of the gray insulation from the UF cable coming out of the post to reveal the three wires encased in it: white, black, and a bare copper (or green) ground. These correspond to like-colored wires on the lantern.
Use wire strippers to expose ½ inch of bare copper on all the colored wires from the post and lantern. Pair the wires from the lantern to those from the post, matching white to white, black to black, and bare copper to bare copper (or green). Twist on wire nuts to hold the pairs together.
Slide the lantern onto the post and tighten its set screws to secure it. Have a licensed electrician connect the wires to the breaker box and install a switch in a convenient location.