For any number of reasons, a lot of rooms, especially bathrooms, don’t have enough electrical outlets. Those rooms probably do have light switches, though, and that’s good news. It’s possible to add an outlet to a light switch line. The better news is there’s usually more than one way to do it. Here are some options.
Replace a switch with a combo switch/outlet
One of the easiest options is to replace the light switch with a combination switch/outlet that fits in the same one-gang box as your light switch. You can even get one that’s GFCI protected, which is ideal for a bathroom. Bathroom outlets always always need GFCI protection. It can save your life. It costs more, but the life you save is worth more than 30 bucks.
For rooms that don’t have running water and don’t have concrete floors, you can use a traditional combo switch, or for rooms where appearances matter, a more modern looking decorator combo switch. I can see going for the decorator combo switch in a hallway. It looks a little better, but then you still have an outlet for those times when you need to plug in something like a vacuum cleaner.
Replace a light fixture with a combo fixture/outlet
Another fairly easy option is to replace a light fixture with one that includes an electrical outlet. Your selection will be limited, but at Home Depot at least, you can get a sconce with an outlet, or a vanity light with an outlet. They aren’t GFCI, so you need to install a GFCI breaker in your breaker box if you use one of these in your bathroom.
Splice in an outlet
You can also splice an outlet into the switch wiring. Add a short white wire to your collection of white wires in the electrical box, and a short black wire to the collection of black wires (a practice known as a pigtail), and run that wire where you want the outlet. If you don’t want to cut into a wall, you can put an extension box on your switch, then use Legrand raceway and electrical boxes to position the outlet in a convenient place.
In a utility room or garage, you can use conduit and 1-gang conduit boxes.