my Old Workshop

How to wire in the great outdoors

If you need to run power outside your house — for lighting, to supply power to a toolshed or garage, or to power a pump in that pond you’re installing, you’ll need to run your wiring underground. Here are some general guidelines, but make sure you check with the electrical inspector first.

Remember, if you just want to install some lighting for effect along the driveway, you can buy lights that run on low-voltage. Connect a transformer to a regular circuit, then bury the low-voltage cable, run it along the ground, or attach it to trees or fences.

If it’s not low-voltage, be prepared for a little more work.

Begin by digging a trench for the wire along a path which avoids trees and roots. If your trench isn’t too long, you can use a shovel, though it’s a bit of overkill. Or rent a walk-behind trencher, which digs down about 2 feet. Lay a bed of fine sand in the bottom of the trench.

To power a few lights, you can simply branch off an existing circuit. Install a weather-tight extension to an outdoor receptacle, and run metal or PVC conduit from this to the bottom of the trench, at which point the underground feed cable can be buried. Cover the wire with sand, then backfill.

Pressure-treated or cedar planking over the sand provides added protection.

When conduit’s required, it’s best to pull the wire through each section before adding bends, as it can be difficult to haul stiff wire along a curving path.

If you need a full circuit — to light and powering a garage, for example — the work’s the same, except that you’ll run the wire from the panel and through an exterior wall, where you’ll install an LB fitting. The conduit extends from this.