Construct A Hydraulic Digging Tool And Use It To Install Electrical Cable Under A Sidewalk
If you are planning to run an electrical cable under a sidewalk, perhaps for a low-voltage lighting project, then you may be concerned about how you are going to get the task accomplished. Digging under a sidewalk can be difficult in the cramped space, and removing too much soil can weaken the sidewalk's base of support and cause a collapse. That's why you should utilize a powerful and efficient means of removing soil: high-pressure water flow. Below is how you can equip an ordinary section of PVC pipe to form an inexpensive hydraulic digging tool that will also serve as a wire conduit:
Tools and supplies needed
- Section of 1-inch diameter PVC Schedule 40 pipe
- PVC cement
- Garden hose-to-PVC pipe adapter (3/4-inch PVC female hose threaded connection to 1-inch PVC Schedule 40 pipe slip fitting)
- Garden hose
- Measuring tape
- Old screwdriver or metal rod
- PVC cutter
1. Measure and mark the sidewalk - with a measuring tape, determine the width of the sidewalk above the location where you wish to install the electrical cable. Draw a chalk line across the sidewalk to mark the path of the electrical cable.
2. Remove soil on both sides of the sidewalk - with a spade, remove the turf and sod by the sidewalk where you wish to place the cable. Dig a hole about 6 inches deep, and poke a screwdriver or metal rod into the soil to determine the depth of the sidewalk. If necessary, dig the hole deeper to find the depth of the sidewalk.
Once you have determined the depth necessary to pass under the sidewalk, dig narrow trenches leading away from both sides of the sidewalk. Be sure to keep the trenches aligned with the mark on the sidewalk; you can use the tape measure to help gauge the straightness of your digging. Dig the approach trench on the side where you wish to begin to a length equivalent to the width of the sidewalk. For example, if the sidewalk is 48 inches wide, dig the approach trench to a length of 48 inches.
On the opposite side of the sidewalk, you don't need to extend the trench as far, but be sure you have adequate room to work. In most cases, allowing at least 1 foot will be sufficient.
3. Assemble the digging tool/conduit - after digging the trench and determining the width of the sidewalk, you need to cut a piece of 1-inch diameter Schedule 40 PVC pipe to the appropriate length. You will need to allow a few extra inches of room, so measure and cut-off the pipe at a length equal to the width of the sidewalk plus 12 inches. For example, if you are cutting a section of PVC pipe for a 36-inch wide sidewalk, then you will need to cut the pipe 48 inches long.
After cutting the pipe to length, use PVC cement to glue a garden hose-to-PVC pipe adapter to the 1-inch PVC pipe. The adapter should contain a 3/4-inch PVC female hose threaded connection at one end and a 1-inch PVC Schedule 40 pipe slip fitting at the other end. Allow the cement to cure for at least 15 minutes before proceeding.
4. Use the digging tool to install the pipe conduit - attach the male end of a standard garden hose to the female connector on the adapter and lay the digging tool/conduit in the trench with the open end facing the sidewalk. Grasp the digging too/conduit tightly and ask an assistant to turn on the spigot to its maximum pressure. Hold the open end of the tool next to the soil under the sidewalk and begin pushing it into the soil when the water starts exiting the pipe. The water will wash away the soil and the pipe should slide into the void created. Continue pushing at a moderate rate of speed until the pipe emerges on the other side of the sidewalk; immediately turn off the water supply once it appears. Remove the garden hose from the pipe.
5. Install the cable - after the pipe has been pushed under the sidewalk, cut the pipe about an inch from the hose adapter and discard the piece. Look inside the pipe to verify it is clear of debris, then push the electrical cable through the pipe to complete the conduit installation.