Certain electrical appliance locations in your home may require more flexibility than just a standard wall outlet. Large rooms or other applications may call for an outlet in the middle of the floor, to provide power away from any walls. Fortunately, adding an outlet to the floor is not a difficult process -- the most intensive part of the job may be running the electrical wire under the floor to the new outlet.
Contact your building department to determine the electrical codes in your area. Floor outlets are a different type than wall outlets, usually with a cover plate and sealed box to prevent safety hazards from moisture. Purchase the correct type of floor outlet box once you have obtained the code requirements for your area, and any applicable permits.
Locate the spot you want to install the outlet, from both above and below the floor. Installing a floor outlet should only be done on a first floor, in an area where the sub floor is exposed from below in either a basement or crawl space. Installing an outlet in an area where the floor is not accessible should only be done by a licensed contractor as it creates special circumstances and hazards.
Drill a small pilot hole into the wood floor from the room where you are locating the outlet down into the floor. Draw the outline of the electrical box on the floor with a pencil. Don't include the flanges or any lip on the top edge of the box, only the outer perimeter of the box itself.
Insert the jigsaw into the pilot hole, and cut from the centre of the area you marked out to one side. Now follow the outline with the jigsaw and cut the hole for the box. Set the box down into the hole to check for fit, and adjust the hole size if necessary, do not cut excess wood away if the box fits, you should have little or no gap around the outside of the box. Do not screw the box in place.
Go to the basement or crawl space, and attach a cable clamp to the end of the electrical wire that will run to your box. Insert the wire up into the box, and working back towards your circuit box secure the wire to your floor joist within 12 inches of the electrical box with the wire staples. Be sure not to penetrate the wire with the staple. Secure the wire to the floor joists as you move back towards the breaker box so that it does not hang down below the floor and is secured out of the way. Do not connect the wire to the circuit box.
Return to the room where the electrical box is being installed. Strip the insulation from the electrical wire; separate the hot, cold and ground wires; then attach them to the outlet receptacle in the proper locations, per the manufacturer's instructions. Most are standard and have a hot, cold, and ground screw that attaches to the corresponding wires.
Screw the outlet into place, and attach the cover to the outlet, securing any gasket or seals that are part of the assembly. Most floor outlets have hinged covers for the plug receptacles to keep liquids from spilling into them.
Turn the power off to the circuit box where you will add the wire for the receptacle. Locate the breaker you are adding the wire to, or get the new breaker if installing one. Strip and attach the wires to the breaker, attach the ground wire to the ground bus bar, and snap the breaker back into place on the breaker bar. Turn the power back on. Test your outlet with a lamp or other small appliance to be sure it is working properly.