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.
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