Time

A full day

Complexity

Intermediate

Cost

$101–250

Introduction

A backyard shed frees up garage space, but unless you power them, their utility is limited. Why not add an electrical circuit? It's a good day's work, but the rewards are many, especially if you're running extension cords across your yard or fumbling around in the dark looking for lawn equipment. No more bruised shins and stubbed toes!

The most confusing thing about running outdoor underground wire is the burial depth. The National Electrical Code (NEC) sets these rules, outlined in table 300.5(A)—and boy, is that table a doozy. Depths range from 4 to 24 inches, and how deep you have to dig depends on the wiring method (direct burial cable, conduit or type of circuit) and the location of the buried wire (everywhere from under your driveway to an airport runway).

Luckily, if you're running a residential branch circuit rated 120 volts or less, protected by a 20-amp (or less) ground-fault circuit interrupter (GFCI), the NEC makes your choice easier. You have several options, but rigid metal conduit (RMC) has the shallowest burial depth (6 inches). Underground feeder cable (UF) is next, with a 12-inch requirement. For this project, we went with RMC, which is more expensive than UF but saves tons of labor on digging. (Of course, you can rent a trencher if you don't want to futz with the conduit.)

Keep in mind that these depths apply to wires run under your yard. Wires under concrete patios, slabs and driveways have different depth requirements. Also, if you're looking to heat and cool your shed, or think you might want to expand later, you'll need a subpanel instead of a single 20-amp circuit. Consult your local electrical inspector or a licensed electrician for more info.

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

Project step-by-step (8)

Step 1

Before You Start

  • Plan where you will get power for your shed.
    • This can be your electrical panel, or a junction box with an existing circuit, if it has the capacity.
    • Make sure you have a safe and accessible way to punch a hole through your house to the outside.
  • Obtain any necessary permits.
  • Call 811, or visit your state’s 811 website to locate buried electrical wires.
Step 2

Plan Your Route

  • Plot the shortest route, with the fewest number of pipe bends, from your power source.
  • Limit your bends to 360 degrees, per NEC rules.
    • The 90-degree elbows going into and out of the ground will consume 180 degrees.
    • If you have a complicated route, use UF instead.
  • Test drill through your house with a pilot bit to make sure your chosen spot doesn’t have any obstacles.
  • Mark your route in a straight line with chalk or marking paint.
  • Measure the route and purchase needed materials and wire.
    • Add at least 10 feet to wire and pipe length so you have a little extra.

Running wires inside rigid metal electrical conduit FAMILY HANDYMAN

Step 3

Dig the Trench

  • Lay a tarp down near your work area to pile dirt on.
  • Remove the top layer of sod and set aside for patching.
  • Dig a trench using a mattock or trencher.
    • A mattock is a narrow shovel, similar to a pickaxe, that doesn’t remove as much dirt as a traditional shovel.
  • Stop when you reach about 8 inches down, so that the top of the RMC will be 6 inches from the surface.

A person in blue jeans and a light shirt uses a pickaxe to dig the ground next to a wooden shed. A blue tarp is spread on the ground nearby, and there are trees in the background.FAMILY HANDYMAN

Step 4

Start Your Run

  • Drill a 1-inch hole through the shed using a hole saw.
  • Hold the conduit body (LB) in the hole and mark the wall where the threads meet the body.
  • Measure the distance from the mark to the bottom of the trench.
  • Bend the pipe into a 90-degree stub, using your measurement and the appropriate deduct (5 inches) for your bender.
    • You can also buy factory-bent 90s (elbows), but this will add cost.
  • Thread the LB onto the pipe and test fit the pipe and LB into the hole.
Step 5

Continue Adding Pipe

  • Remove the pipe and LB from the shed and trench (it’s easier to tighten on flat ground).
  • Add pieces of pipe until you reach the house, tightening the fittings with 2 wrenches as you go.
  • Leave enough room on the end to add a final 90-degree stub, cutting the last straight pipe if necessary.
    • Remove metal burrs from cut pipes with a small metal file, or by sticking your pliers in the opening and rotating them back and forth.
  • Add a compression fitting to the cut end of the pipe, if you had to cut it.
  • Place the pipe in the trench and attach the LB to the shed as in the image below.
  • Leave the inside locknut loose so you can adjust and remove if necessary.

Machine parts labelled. FAMILY HANDYMAN

Step 6

Complete the Run

  • Drill a 1-inch hole in your house with a hole saw.
  • Thread a compression fitting into the LB, and attach it to the house (see above).
  • Measure the distance from the end of the trenched pipe to the wall, taking into account the siding.
  • Bend the pipe into a 90-degree stub, using your measurement and the appropriate deduct (5 inches).
  • Hold the pipe in place and mark it for cutting at the LB and the trenched pipe (if necessary).
  • Slip the pipe into the LB compression fitting and connect the other end into the trenched pipe.
  • Tighten all connections, including the locknuts inside the house and shed.
    • For locknuts, place a flat screwdriver into an edge groove and hit it with a hammer.
  • Apply duct seal where LBs enter your house and shed to repel water.
Step 7

Pull Wire and Add Switch

Sheds must have a disconnect located in a readily accessible location near where wires enter the shed. For 20-amp circuits, this can be a single-pole switch.

  • Take off the covers to the LBs, and push a fishtape through the pipe from one end to another.
  • Attach the conductors to the fishtape and pull them through.
  • Remove wires from the fishtape and push them into the house and shed.
  • Leave about a foot of wire at each box.
  • Wire a switch in the first box that enters your shed.

A person wearing gloves uses a green fish tape to guide wiring through a metal conduit next to a house. They are kneeling on a blue tarp, with green plants visible nearby.FAMILY HANDYMAN

Step 8

Finish the Project

  • Run non-metallic sheathed cable (NM-B) from the shed disconnect (switch) to a GFCI receptacle, then to the rest of the shed receptacles.
    • Outdoor and accessory building receptacles must be GFCI-protected.
  • Run NM-B to the lights.
  • Complete wiring at the house, or call an electrician for assistance.
  • Backfill your trench and press the sod into place.

An open electrical junction box mounted on a wooden surface, showing exposed wiring with wire connectors. The metal cover is hanging to the side, revealing black, white, and green wires connected inside.FAMILY HANDYMAN

Author
Ally Childress
Ally Childress writes practical, informed stories and how-to guides for Family Handyman and Reader’s Digest. An experienced electrician, Ally's beat naturally includes electrical and construction topics. She also tackles cleaning, gardening, technology, bugs and anything else you can throw at her. She has a knack for finding just the right subjec...
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Ally Childress