How to Install Electrical Conduit Into Cement Block Walls
Most basement walls are made up of cement blocks. When you want to run electrical wiring over the walls to either finish your basement or add a surface-mounted electrical box, you must run the electrical wiring through a metal tube called conduit. Conduit comes in straight lengths. You then bend the conduit to form the route leading from one electrical box or power source to another electrical box. You surface mount the conduit into the concrete with conduit straps and masonry screws.
Design the run of conduit from one electrical box to a second. While planning, keep in mind that it is easiest to bend conduit at either a 45- or 90-degree angle; plan your run accordingly. If complex conduit runs are necessary, use a protractor to determine the required angles.
Measure the distance from the first electrical box, which already mounted to the concrete wall, to the first bend and subtract 5 inches. Transfer this measurement to a piece of conduit.
Insert the conduit into a conduit bender's slot and line up the mark on the conduit that you made with the bender's arrow. Lay the conduit and conduit bender's head on the ground. Step on the portion of conduit not being bent to hold it in place. Pull up on the conduit bender's handle to bend the conduit until it is bent up even with the conduit bender's degree mark equal to the bend you need. For example, bend the conduit to the bender's 45-degree mark for a 45-degree bend.
Set the conduit up against the cement wall. Hold the new electrical box on the wall in the location you are installing it and place a mark on the length of conduit you need to reach the location. Remove the conduit from the wall and cut through it at the mark, using a hacksaw.
Place a screwdriver against the knock-out holes you wish to remove from both electrical boxes. Hammer on the screwdriver's handle to remove the knock out. Insert an electrical connector into each hole. Insert the conduit into the electrical connector. Place a level on the conduit and make any necessary adjustments to make the conduit level by moving it slightly up or down. Tighten the electrical connector's screw to hold the conduit in place.
Set a conduit strap over the conduit and against the concrete wall every 18 to 24 inches. Drive a masonry screw through the strap's screw holes to secure it in place.
Insert the conduit's other end into the second electrical box's electrical connector. Place a level on the conduit and make any necessary adjustments to make the conduit level. Mount the electrical box onto the wall. Tighten the electrical connector's screw to hold the conduit in place.
- Instead of bending your own conduit, you can purchase conduit bends at your local home builder's store. Attach the conduit bends to straight conduit with a coupling.