How to Replace a Lamppost

In this video, master electrician Heath Eastman helps a homeowner replace his lamppost that is not exactly to code.

To start, it is a mailbox post, not even a lamppost. The top is wide open to water infiltrations, only held down by a zip tie. It also uses a voltage way too high to use for residential outdoor usage. All in all, it’s an electrician’s nightmare.

Steps for Replacing a Lamppost:

Step 1: Call in the pros to help

• Installing a brand new post from scratch will require installing a light switch and connecting it to the nearest electrical source.
• A trench will need to be dug for the wires and a utility locating service will need to be called in to make sure the digging is done safely.
• Then the wires can be connected from the new lamppost to the light switch.

Step 2: Ensure the wires are GFCI protected

• In this case an underground feeder cable was already in place. UF cables are designed to be buried directly underground without conduit.
• Although Heath prefers to see conduit to ensure that the wire stays protected, as long as the cable is GFCI protected then it meets the code requirements.

A GFCI, or ground-fault circuit interrupter, works by sensing the current flowing into a device and comparing it to the current flowing back out. As This Old House electrician Mark explains, “If this sees a slight imbalance, something as small as 5 milliamps, it’ll turn the power off to help prevent you from getting shocked.” This protection is especially critical for outdoor circuits like a lamppost, where moisture and ground contact increase the risk of electrical faults.

Pro Tip: Heath, the This Old House electrician, explains that when installing a new lamppost from scratch, “we have to call a utility locating service, dig a trench. We’d want to put a conduit in the ground, preferably 18 inches down, and pull the lines from the house over to where the post is going to go.” Since this project already had existing wiring in place, much of that groundwork was already done.

Step 3: Start with turning off the power

• After the power is off, disconnect the lantern from the wires and remove the old post.

Step 4: Dig a hole for the post

• Dig about 6 inches deeper than what you want for the post.
• Add gravel to create a place for water to drain so there’s no water buildup.

Pro Tip: This Old House Magazine recommends lining the bottom of the hole with 6 inches of gravel, then filling the remaining 16 inches with cement. About 16 inches of concrete will keep the post stable, because “rains and frosts and even droughts can shift the soil” — a stable footing is essential to keep the post aligned and standing straight.

Step 5: Place the post into the ground

• Make sure the post is facing the correct way. If there is a hole for the sign arm, face it towards the street.
• If there is a hole for the wires, face the hole away from the street.
• Make sure the post is level. Backfill the hole and pack down the dirt, checking the level as you go.

Pro Tip: Before setting the post, mark it with a pencil at the desired burial depth so you’ll know exactly how deep to plant it in the hole. This simple step ensures consistent depth and saves you from having to re-measure once the post is in position.

Pro Tip: On a This Old House project, landscape contractor Roger Cook recommended backfilling with a specific material: “It’s called pack. It’s a mix of three quarter stone and stone dust, it really firms up and it’ll hold this post in place, but more importantly, it drains. So there won’t be excess water up against the post and it won’t rot out.” Fill the hole all the way to the top, compacting in layers as you go up.

Step 6: Install the base

• Also install the sign arm, and top cap.

Step 7: Make the wire connections

• For this lamppost the wire was just too short to make it to the light fixture. To fix this Heath added a receptacle to the side of the post, made a splice, and ran a new wire to the lamp.
• Drill a hole where the receptacle will go into the post for a conduit connector. This will prevent any water that gets into the lamppost from getting into the receptacle box.
• Splice the old wire and new wire together.

Step 8: Add the light fixture and sign if applicable

• Turn the power back on and test it out.

TIP

Splice for underground wiring

The HST 1300 Underground UF Splice Kit for 14- to 8-gauge wire (Gardner Bender) has screw-down connectors to ensure firm contact with the wires. The connectors are then sealed inside moisture-blocking, heat-shrink sleeves.

Resources

Lampposts usually come in at least two pieces: the post, and the lantern. In this case, Heath installed a Hammond Lantern Post with Sign Bracket for the post and a Jefferson Post Mount Lantern for the lantern. This particular post was designed with a hanging sign in mind, which can be custom ordered separately. All of these items are manufactured by Walpole Outdoors.

To safely extend the UF cable, Heath decided to install an outdoor-rated receptacle, wire it with the UF cable, and then run a new cable from the receptacle to the lantern. He protected the receptacle using an Expandable Weatherproof In-Use Cover, which is manufactured by TayMac.

Materials

• Lamppost
• Lantern
• Gravel
• Outdoor-rated receptacle
• Watertight conduit connector
• Weatherproof receptacle cover

Tools