Adding an electrical outlet is not that complicated. DIY people who mount their own TV’s might want to consider adding an electrical outlet before mounting the TV making your TV mount project cleaning with a modern look.

To do this you need to consider a few things when choosing the correct electrical box and wire. Here is a quick guide on the different electrical boxes for outlets and switches. 


Types of Electrical Boxes

We first start off with the type of box. There are a few different types of electrical boxes. 

Metal or plastic, sizes and new work vs old work. 


New Work: This refers to new construction, this usually means that the drywall has not been hung yet and you can mount the box directly on to the stud with a nail from the outside of the box. 


Old Work: This refers to a build house, an old work box is designed to mount to the drywall, either by a butterfly with a screw that tightens on to the drywall or by drywall screws. 


There is also an Old Work Box that has a wood stud screw from the inside, this is in case you are installing the box by a stud. It is a better, more secure install to mount the box to the stud if possible. 

Metal Vs Plastic Electrical Box

Depending on the wire that you are going to use you choose the electrical box you need. Non Metallic wire, meaning Romex or NM wire (2 conducting wires and a ground) use a plastic electrical box.

Metallic cable, meaning that it is run in a metal conduit case uses a metal electrical box. The metal box has an exterior clamp, this helps in cases where you have lots of wire running through the box and you need room to stay within the code. It is also more common in commercial settings as it protects the wire within.


What is the Code for calculating box size?

314.16 (B)

  • Single Gang Boxes: A total capacity of 18 cubic inches allows for 9 #14 gauge wires, 8 #12 gauge wires, or 7 #10 gauge wires. This is a wires-only capacity. With one device added to the box, subtract two wires in each category.
  • Double Gang Boxes: A total capacity of 34.3 cubic inches allows for 16 #14 gauge wires, 15 #12 gauge wires, or 13 #10 gauge wires. When two devices are added to the box, subtract three wires in each category.


If you are simply adding an outlet behind your TV or some other simple task you don’t need to worry yourself with this type of calculation. Just make sure that you’re only running the incoming wire and the new one going out, you can also run 2 out going in case you’re adding more than 1 outlet. Make sure your wire is clamped to the electrical box. 


A Single Gang is for 1 outlet or switch. A Double Gang Box for 2 outlets, switches or a mix. 

You also have the option to buy a box that the sides can be removed letting you add boxes as you go, turning a double to a triple or more. 


In this article I am referring to an outlet or light switch box, there are many more types of boxes, some designed for ceiling fans or light fixtures. Some of this information can be useful while other is not for those types of boxes. 


I’ve chosen my electrical box and wire. 


Once you have decided what type of wire and what type of box you need your next step is to choose where it goes, mark the size of the box, cut the drywall, run your fish wire, fish your wire and install your new outlet. I recommend doing all of this and for the last step connecting the new wire to the power source. 


In the video I showcase a small job we did at a commercial building. As always if you are in the Phoenix metro area and would like Response Crew Handyman’s help doing this or any other project send us a message or give us a call at 480-525-9825