Installing underground electrical cable

Q: How should I install a buried electrical cable? To cut down on costs, I plan to dig a trench myself and lay wires from my house to an outbuilding that I’m constructing. Does the trench need to be below the frost line? Does the cable have to run in some sort of plastic pipe?

A: There are some very specific requirements for burying electrical cable safely, and in all areas of North America the process needs to involve inspections by a local standards organization. Where I live it’s called the Electrical Safety Authority (ESA). It's not unusual for homeowners to complete electrical work on their own. This is fine and perfectly legal as long as you don’t sidestep the inspections process. Start by contacting your local electrical authority and tell them what you have in mind. Electrical installations like yours require three separate inspections. The trench inspection is the first and examines that cable is laid properly underground. The best option is to run these wires in PVC conduit that's buried to a specific depth, depending on the situation. Many jurisdictions also require that you install plastic warning tape in the trench before covering conduit completely with soil. This serves as an alert for people who might be digging where they shouldn’t. Next, you'll need a rough-in inspection. This verifies the safety of wiring after it's installed, but before it's concealed with finished wall coverings. The final inspection is when the job is complete, after all switch covers and plug plates are in place. I know this sounds cumbersome, but it's really not that bad. I’ve gone through this process myself several times. And besides being easy, electrical inspections are required by law and necessary to validate your insurance coverage. If an electrical fire or accident ever occurred, any lack of inspection papers would come to light and cause you a great deal of grief.