The most common need people have is adding an additional outlet box. They never are where you need them! As with anything electrical, take proper precautions against electrical shocks and know your local codes for proper cable types, shielding plates, etc.

Sometimes it just your lucky day and the room on the other side of wall has an outlet that is very close. Back to back is ideal but even one stud off is not a problem. Just make sure the circuit won't be overloaded by adding an additional set of plugs.

Use a stud finder and find out where the adjacent studs are for where you want to put the outlet box. Depending on the type of box you have, either cut out the proper size hole next to the stud or somewhere in the center. I prefer the renovation boxes with the tabs that are designed to fit in the drywall away from the studs. Align your box hole so it isn't directly behind the other box as two deep boxes won't fit back to back in a two by four stud wall.

If you are within the same studs, it is now a simple matter of running the proper wire or conduit from the old box to the new one. If you need to go one stud over, cutting your hole close to the stud makes it a little easier. From the box hole access, drill a hole in the center of the stud following proper guidelines to maintain structural integrity. Keep the hole size at a minimum and no more than 40% of the stud width.

If instead you want to extend power from an existing box in the room, there are several ways to run the wire between the boxes. One common method is to remove the baseboard trim. Then cut out some of the wall board behind the baseboard and make small notches (not to exceed 25% of the stud width) in each stud or drill holes in the center of each stud to run the cable for the extension. After installing the cable, make sure to use steel plates on each stud if you did notches to prevent any drywall screws from penetrating the wires.

If you drilled holes in the center and come to a corner, it can sometimes be problematic when it is solid. You need to drill a hole from each side until they meet. Then either fish something flexible through the hole or use two fish tapes with a hook on the end and get them to catch. Put lots of lube on the cable and pull it through.

Going around doors is a similar exercise. The best way is to remove the trim molding and usually there is enough room with minimal notching to run the cable around the door.

If you have attic or basement access, there is another way to run new cable. Drill holes through the plate where the existing circuit is and where you want to add an additional outlet. Sometimes you will run into fire stops or cross braces in the middle of the wall. If you are putting in a switch, many times you can get close enough from the switch box hole to drill through the brace. Otherwise you will need to cut out a small section of wallboard and make a notch.

So you can see there are many ways you can add an outlet box without having to damage the existing drywall. Just take care and use proper electrical safety procedures and follow all your local electrical codes.