Tim Carter of Ask the Builder, demonstrates how to drill a hole under a sidewalk, driveway or walkway so you can install an underground wire.
If your project calls for running a small cable or wire under an existing patio, sidewalk or driveway, there is an easy way to do it, without laying on your stomach with a shovel. Use a piece of PVC pipe with a chisel cut. This will serve as your drill bit.
First, create a small drench perpendicular to the sidewalk to create some working room for the pipe. Once the drench has been cut, use a sledge hammer to drive the PVC pipe a few inches into the ground. Twist the pipe to break off the dirt and remove the pipe. The end will have dirt in it from under the sidewalk. Take another small diameter pipe or rod and drive the dirt out of the chiseled pipe. Continue driving it in a very inches at a time until you have reached the other side.
You now have your tunnel to run the cable or wire under the sidewalk. If you leave the PVC pipe under the sidewalk, it will serve as a nice conduit if you need to run another wire at a later date.