Expanding Circuits in Electrical Boxes: Safely Securing Cables
While working on an old box, you will most likely discover that the wires are oftentimes crammed into it. Not only does the undersized box not have enough room for working, but more important, the wires can be damaged, creating a major fire hazard.
Keep yourself protected,the NEC (National Electric Code) prescribes the maximum number of wires the can be placed into specific-size boxes. The gauge (size) of the wire also determines the number of wires allowed in the box ( the larger the wire, the fewer goes in the box).Additionally, if you have other devices in the box, maybe a switch, receptacle, clamp, strap, or grounding conductors, you will have to deduct a certain number of wires from those allowed in the box.
After making your deductions, if you find you know longer can place enough wires for the job into the box, simply use a larger box. Just make sure you check with your local codes to determine the size of the box that will be best suited for the job.
Nailing without a hammer (Tip)
To nail a box to a stud where there is not enough room to swing a hammer, use a C-clamp. By tightening the clamp you can squeeze nails through the holes in the side of the box and into the stud.
Do not Overload
Before supplying a new outlet or fixture to a circuit, make sure you have more than enough room for it. Count the existing number of outlets and fixtures on the circuit you plan to add to. A good rule of thumb is to have no more than a total of 8 outlets and fixtures on a 15-amp circuit, and no more than 10 on a 20-amp circuit.
Secure your Cable
How you secure the cable at the box depends on the type of box you use. For a single-gang nonmettalic box, secure the cable by placing a molded plastic strap over it within 8 inches of the box, then nailing the strap to the stud. In a double-gang nonmettalic box with built in clamps, bind the strap to the stud within 12 inches of the box. In some areas local codes require use of a metal box. The box may or may not have built-in clamps, or it may require using bushings and locknuts.
Box support
When mounting a new box in wallboard, use brackets to hold it in place. Fist thing you want to do is outline the box with a pencil (but leave out the ears). Now cut along the outline with a utility knife or (wallboard knife). With the cable clamped in the box and the ears adjusted so the box rests flush to the wall, hold the box in the wall while you slip a bracket on each side of the box between the wall and the box. Use long-nose pliers, to pull the tabs on each bracket forward while pushing the box back with a screwdriver; then fold the tabs against the side of the box. “You are done”.
Keeping the elements out
“One last thing!” Uninsulated outlets can let in a cold draft from your basement or attic into the room. They can also be a source of heat loss. You can insulate an outlet with a foam gasket (available at most home centers). To install the gasket, unscrew the cover plate of the outlet and simply slip the gasket behind it with the smooth side facing out. Trim the foam with scissors.”Now you are done!”
