How to Install an Electric Socket Outlet in a Wood Floor?
1) Position a deep single-gang outlet box onto the floor in the desired location of the socket outlet. Check for the locations of the nearest floor joists with a stud finder, and adjust the position of the outlet box so that it will not interfere with a floor joist. Mark the perimeter of the outlet box onto the floor with a pencil.
2) Drill a 3/8-inch pilot hole into two opposing corners of the outline using a power drill. Then cut out the perimeter of the hole using a jigsaw. Slip the single-gang box into the hole, and adjust the cut for any tabs on the outlet box.
3) Remove one of the knockouts on the edge of the outlet box to accommodate the electrical cable. Then slip the box into the cutout, and attach the box to the wood floor with four 1-inch wood screws.
4) Locate a junction box beneath the floor into which you wish to connect the cable for the new outlet. Remove the cover of the junction box with a screwdriver, and turn off the breaker to the circuit governing the junction box. Verify that the power is off by holding the tip of a noncontact electrical tester against the black wires within the junction box. If the light illuminates, turn off other circuits until you have verified that the power is off.
5) Push about 8 inches from one end of a 14/2 electrical cable into one of the knockouts of the junction box. Tighten the cable clamp to hold the cable in place, then route the wire to the new outlet box. Tack the cable to the floor joists along the route with electrical staples using a hammer. Cut the cable and slip about 12 inches of the end of the cable through the open knockout of the outlet box.
6) Remove the outer sheathing of the new electrical cable at the junction box with a utility knife. Then strip off 1/2-inch of insulation from the tips of the black and white wires with wire strippers. Remove the wire nut from the joined black wires within the junction box, and add the new wire to the cluster before twisting a new wire nut onto the junction. Repeat in kind with the white and bare wires. Tuck all of the wires into the junction box, and secure the cover by tightening the mounting screws.
7) Go back into the room where the new outlet will be located, and tighten the wire clamp around the cable with a screwdriver. Remove the outer sheathing from the electrical cable, then strip off 3/4 inch from the insulation on the black and white wires. Twist a loop into the ends of all three conductors with a pair of needle-nose pliers.
8) Wrap the loop of the bare wire around the grounding screw of a new electrical outlet, and tighten the screw with a screwdriver. Then wrap the white wire around one of the screws labeled "common," and tighten the screw. Finally, wrap the black wire around one of the screws on the opposite side of the outlet, and tighten the screw.
9) Push the wires into the outlet box, and mount the outlet to the box with the two attached screws. Then turn on the circuit breaker, and test the outlet. If the outlet functions as needed, attach the floor outlet cover to the face of the outlet.