Installing power to your backyard shed can be a challenging DIY project. Running electrical wires underground on your property requires proper planning, materials, and safety precautions. Follow this step-by-step guide to learn how to safely and properly run underground electrical wires to supply power to your backyard shed.
Research Local Building Codes and Permit Requirements
The first step is to research your local building codes and permit requirements. Most jurisdictions require a permit to run new electrical wiring on your property. Make sure you:
- Check with your local building department on permit needs, inspection requirements, and code regulations for outdoor electrical wiring projects.
- Know the required burial depth for underground wires in your area - commonly 12-24 inches.
- Use only approved outdoor-rated wiring. UF cable (underground feeder cable) is the proper cable type.
- Have all work inspected by the building department when complete.
Permits help ensure your DIY electrical project is up to code. It's better to be safe than sorry down the road.
Calculate Electrical Load and Conductor Size
Before digging, determine what the electrical load will be in your shed and size your wires accordingly. Consider all lights, outlets, and equipment you plan to run in the shed. The load calculation will determine the proper wire size.
Some key factors:
- Measure the length of wire run from your home to the shed location.
- Calculate total wattage of all lighting, outlets, and devices.
- Identify voltage - usually 120V or 240V.
- Allow for some future expansion capacity.
Larger wire gauges are needed for longer wire runs and higher electrical loads. Using wire that's too small can cause unsafe voltage drop. Don't skimp on the size.
Choose a Trench Route from House to Shed
Map out the underground route to take from your main electrical panel to the shed. Consider:
- The most direct buried route to save on wire and excavation.
- Any obstructions to dig around like patios, trees, gardens.
- Any easements or property line setbacks to observe.
Measure the total length of the trench run. You'll need this info when purchasing the wire. Mark the route with small flags or spray paint so you know where to dig.
Use Proper Electrical Conduit
The wires must run through buried PVC conduit to protect them.
- Use schedule 40 PVC or thicker conduit rated for electrical use.
- Sizing depends on the number and gauge of wires inside.
- Conduit provides protection from damage and grounding.
- Elbows and junction boxes may be needed if there are bends.
Consult an electrical code guide to ensure you use the right size conduit for your wire run.
Dig the Trench Safely
Now comes the hard work. Digging a trench safely requires:
- Calling 811 to locate any buried utility lines on your route, like gas lines or fiber optic cables.
- Using a shovel, excavator, or trencher appropriate for the width and depth needed.
- Making trench walls vertical and clearing debris as you go.
- Providing any shoring for deep trenches per OSHA standards.
- Piling dirt back from the edge to avoid cave-ins.
Go slow and be cautious when digging near utility lines marked from your 811 call.
Lay the Conduit and Wires
With the trench fully dug, you can lay the underground wires:
- First lay the conduit in the trench bottom and join pieces with waterproof conduit adhesive.
- Pull the electrical wires through the conduit using a fish tape or string.
- Use wire connectors rated for direct burial when splicing wires together.
- For the shed, install a small junction box on the end of the conduit to transition to indoor wiring.
- Don't forget to backfill with a couple inches of sand or gravel to provide a nice bedding for the wires.
Take photos at each step of the process. This will help with inspector approval.
Backfill and Compact the Soil
Filling in the trench correctly helps keep your underground system intact:
- Backfill with your native soil, free of large rocks or debris that could damage wires.
- Tamp down the soil in layers using a hoe, plate compactor, or lawn roller to compact tightly.
- Mound the last few inches above grade to account for settling.
- Don’t run over the wire zone with heavy machinery or vehicles.
Proper backfilling avoids sagging wires and conduit damage over time. Check local codes for any requirements.
Connect to the Main Panel and Shed
The final step is making the electrical connections:
- Attach the feeder wires from the conduit to a new circuit breaker in your main home panel.
- Maintain phase continuity by connecting black wires to black, red to red, etc.
- Use appropriate amperage and voltage rated breakers - consult an electrician if unsure.
- Connect the other end of the wires at the shed junction box to indoor receptacles or lights.
- Attach a ground rod at the shed with a #6 copper ground wire for safety.
With all connections made securely, you can restore power and request an inspection. Enjoy your new backyard power source!
Running underground electrical to your shed or outbuilding is very rewarding but requires planning and adherence to electrical codes and safety standards. Do your homework in advance, use proper materials, and don't be afraid to hire a professional electrician if needed. Taking the time to do it right ensures you'll have safe and reliable power in place for years to come.