Electrical Wiring: How to Run Electrical Wire Outside

The easiest way to bring electricity to a shed, garden or lamppost

Next Project
Time

A full day

Complexity

Intermediate

Cost

$101–250

Introduction

Learn how to run electrical wires outside underground to reach sheds, lights, patios and other locations, following safe wiring practices.

Tools Required

  • 1-in. drill bit
  • 4-in-1 screwdriver
  • Drill bit set
  • Drill/driver - cordless
  • Hacksaw
  • Pipe wrench (2)
  • Pliers
  • Spade
  • Tape measure
  • Torpedo level
  • Wire stripper/cutter

Materials Required

  • Duct seal
  • Electrical boxes
  • Electrical tape
  • EMT (electrical metallic tubing)
  • Fish tape
  • Fittings (connectors and LBs)
  • GFCI
  • Leather gloves
  • Mattock
  • Pipe bender
  • RMC (rigid metal conduit)
  • Stranded electrical wires
  • Switch
  • Two (white and black) conduit straps
  • Wire connectors

Overview: Project Scope, Special Tools, Materials and Costs

Dragging extension cords across the yard to power the string trimmer, fumbling around in a dark shed…most of us take these hassles for granted. But it doesn’t have to be that way. With a day’s work, you can run electrical lines to any part of your yard.

This article will show you how to bring power to a shed, but the process is almost identical if you want to simply mount an outlet on a post planted in the soil.

A licensed electrician would charge at least several hundred dollars plus materials to run lines from your house to a shed 50 feet away (not including any work inside your house).

Running Power Through RMC

We’ll show you how to run wires through rigid metal conduit (RMC). This method offers the best protection of the wiring and requires the least amount of digging. It also lets you install a GFCI outlet at the end of the line rather than at the house, which means you’ll never have to run back to the house to reset a tripped GFCI.

If you want to provide a dedicated circuit to the shed, hire an electrician to make the final connection in your main electrical panel. Otherwise you can connect to an existing circuit if the circuit has enough capacity and the box you’re connecting to has enough volume for the additional wires.

Running Wires Inside Rigid Conduit

To run the wires inside rigid conduit, you’ll need a hacksaw, a pipe bender capable of bending 1/2-in. rigid conduit with an outside diameter of 3/4-in., and a fish tape long enough to reach through the buried pipe.

You’ll also need a pair of pipe wrenches to screw the sections of pipe together, a drill and one-inch bit capable of penetrating your siding, and wire cutting and stripping tools.

A few weeks before you start the project, contact your local building department to obtain an electrical permit if one is required. Then a few days before you dig, call 811 to have your underground utility lines marked. Learn more at call811.com.

Project step-by-step (12)

Step 1

Running Power Through RMC

We’ll show you how to run wires through rigid metal conduit (RMC). This method offers the best protection of the wiring and requires the least amount of digging. It also lets you install a GFCI outlet at the end of the line rather than at the house, which means you’ll never have to run back to the house to reset a tripped GFCI.

If you want to provide a dedicated circuit to the shed, hire an electrician to make the final connection in your main electrical panel. Otherwise you can connect to an existing circuit if the circuit has enough capacity and the box you’re connecting to has enough volume for the additional wires.

Running Wires Inside Rigid Conduit

To run the wires inside rigid conduit, you’ll need a hacksaw, a pipe bender capable of bending 1/2-in. rigid conduit with an outside diameter of 3/4-in., and a fish tape long enough to reach through the buried pipe.

You’ll also need a pair of pipe wrenches to screw the sections of pipe together, a drill and one-inch bit capable of penetrating your siding, and wire cutting and stripping tools.

A few weeks before you start the project, contact your local building department to obtain an electrical permit if one is required. Then a few days before you dig, call 811 to have your underground utility lines marked. Learn more at call811.com.

Using Metal Conduit Means Less Digging

  • Running wires inside rigid metal conduit (RMC) is a little more expensive than burying underground feeder cable (UF), but it saves labor.
  • This is because the top edge of RMC has to be only six inches below the surface of the ground, while UF must be buried 12 inches deep (deeper in some situations).
  • That extra six inches of trench depth may not seem like a big deal. But it adds hours of backbreaking work, especially if you have rocky soil, hard clay or lots of tree roots.

Metal Conduit Means Less DiggingFamily Handyman

Step 2

Plan the Conduit Route and Dig the Trench

  • Use a mattock to dig the trench. The narrow head means less dirt to remove and less to put back.
  • Slice out strips of sod with a spade so you can neatly patch the lawn later.
  • There are several factors to consider in planning the route from the house to the shed.
    • Obviously the shorter the trench, the less digging you’ll have to do. But you also have to determine where you’re going to connect to power inside the house and how easy it will be to get there.
    • In some cases, a little more digging could save you from having to tear into a basement ceiling.
  • Start by locating a power source, whether it’s your main panel, a ceiling box, outlet or other electrical box.
  • Then figure out the best spot for the new conduit to enter the house.
    • Pro tip: Since the National Electrical Code (NEC) limits the number of bends you can make in the pipe to a total of 360 degrees, you have to plan the route carefully. The two 90-degree bends from the ground into the house and shed consume 180 degrees, leaving you 180 degrees more for any additional bends.
  • With the route planned, you can measure for the amount of wire and conduit you need and head to the hardware store or home center.
  • Add 10 feet to the length of wire and pipe to make sure you’ll have enough.
  • It’s smart to drill the hole into the house before you start digging just in case you run into an obstacle and have to choose a new location.
  • When you’re sure of the exit point, dig a trench from the house to the shed.
    • Pro tip: If you’re going across a lawn, remove a slice of sod the width of a spade from the surface and set it aside to reuse after you bury the pipe.
  • Then use a mattock or narrow spade to dig the trench.
  • Pile the dirt on plastic tarps so you don’t have to rake it out of the grass later.

Plan the conduit route and dig the trenchFamily Handyman