Wiring a new residential home is challenging enough when the home is built from mostly wood material. However, some homeowners choose to build their exterior walls from concrete blocks to save time and money. Wiring, in this situation, becomes slightly more challenging, since the capability to nail up electrical boxes and drill holes to get wire to them is lost. Concrete block walls require you to perform a few extra steps when installing electrical boxes for outlets.
Decide where all of your electrical sockets need to be located. Before laying any concrete blocks, check with your local electrical inspector to find out the proper height and distance between electrical sockets required by the National Electrical Code.
Mark on the floor, with chalk, the location where each outlet needs to be located in the wall. This gives you a visible reference point so you do not miss any outlets while block is being laid.
Prepare your outlet boxes and PVC conduit. Cut PVC conduit into 5-foot sections. Using PVC cleaner and glue, attach a box connector to one 5-foot section and a coupling to the other end. Knock out the prefabricated hole in the top of an outlet box using a flathead screwdriver and hammer. Insert the end of the conduit, with the box connector attached to it, into the hole, and fasten with the supplied locknut.
Follow the block masons. When the block reaches the area of your outlet, use a single outlet box to mark the appropriate area where the final box needs to be situated. Hold the outlet box in the correct position on the block surface, and trace the perimeter of the box with a pencil. Using a grinder, cut the space out of the block.
Fill, with cement, the cavity of the block up to the point where the outlet box sits. Once the cutout block is in place, situate the outlet box and conduit in the correct position. Ensure the open face of the outlet box is flush with the home interior block surface. Place wood shims into the small open areas between the face of the box and block to help hold the box in place. Repeat this process for all other outlets.
Track the progress of the block masons. As the height of the block reaches the top of the first 5-foot length of conduit, using PVC cleaner and glue, attach another 5-foot section. This should be enough conduit to reach the top of most residential walls.
Cut off the excess conduit when the block reaches the final height. You need approximately 1 or 2 inches of exposed conduit above the block surface. With PVC cleaner and glue, attach a box connector to the end of the conduit. Twist a PVC plastic bushing onto the threads of the box connector. Cover the end of the conduit with a piece of duct tape until the rest of the home is completed and wiring takes place.
While you are waiting for the block layers to reach the height of your first 5-foot length of conduit, it is a good idea to cover the end of the conduit with duct tape. This keeps out any debris that may fall into the conduit from the laying of the block.