Steps:1. Put the sconce in the desired location on top of the cross section and trace around it lightly. Set the sconce aside and drill a hole in the cross section large enough for the cord to pass through using a spade bit. Tip: Drill until just the pointed tip has come through the other side, and then turn the cross section over to complete the hole to prevent splintering.
2. Rout a groove along the back of the cross section from the hole to the bottom edge using a jig made of four 1x2s nailed together as a guide (figure A).