How to Rough Wire Electrical

A junction box not located safely.

Roughing in electrical wiring will need to be done prior to installing wallboard in a new home or addition. You will need to know the amount of power supplied to the home and the total electrical load the breaker panel can carry and to map out the circuits prior to beginning installation. In most areas, a licensed electrician must sign off on work like this and you'll need to have approved plans before you start so you don't have to rip it out and start over. Save money in the middle by roughing it in yourself.

Things You'll Need

• Copy of approved electrical schematic for the home
• Tape measure
• Protective eyewear
• Cordless drill
• 3/4 inch paddle bit (spade bit)
• Juncture boxes
• Screwdriver with standard/flat blade
• Flexible nonmetallic wiring (Romex)
• Staple gun and staples
• Cable clips
• Screws

Instructions

1. 

   An electrician going over schematic

   Purchase electrical cable according to what your electrician told you when going over your schematic. You will likely need 12-gauge nonmetallic flexible cable that is rated for 20 amps, 14-gauge nonmetallic flexible cable that is rated for 15 amps and, if you're roughing in an electric kitchen stove, 6-gauge three-conductor service-entrance round (SER) cable that is rated for 50 amps. Purchase junction boxes and any other materials you may need.

2. Use the tape measure and pencil to measure and mark the locations of the light switches and electrical outlets (also called receptacles) onto the wall studs. Outlets are usually placed 12 inches up from the floor, and light switches 48 inches up from the floor. Install the junction boxes by nailing or screwing them into place on the side of the appropriate stud. Position them so that when the 1/2 inch thick drywall is installed the junction boxes will be flush with the drywall.

3. 

   Bore holes in studs for electrical cable.

   Drill holes in the studs for running the cable. Mark the location of the center of each hole, which must be located 1 1/4 inch from the back face of the stud, and from the front face of the stud. In standard 2x4 stud walls, this means the center of the hole must be in the center of the 2x4. Use the drill and 3/4 inch paddle bit to bore a hole all the way through the stud. The cable will come from the breaker panel or subpanel and run through each of the holes between the panel and the light switch or electrical outlet that it will supply with electricity. You can think of the breaker panel as the base of the plant and the cables as vines branching out from it. All of them originate at the panel then go in whichever direction they need to go to get to their switch.

4. Run the appropriate cables from the outside of the breaker panel, leaving about 12 inches of slack, through the holes in the studs to the location of the light switch or electrical outlet. Do not wire the cables into the breaker panel. Do not attach them to the studs yet. Do not attach them to any switches or receptacles yet. Leave about 12 inches of slack at the end of the cable and cut the cable. Run each circuit in the same manner.

5. 

   Proceed after checking electrical design.

   Check the schematic. Make sure you have run the correct cabling to the future location of each individual appliance, lighting fixture, switch and outlet. Checking for accuracy now can save you a lot of time and possibly expense. If there is an error, now is the time to catch it.

6. Staple the cable into place, taking care not to puncture the cable with the staples. Building codes in many places prohibit stapling two lines of cable on top of each other on a stud, so use cable clamps anywhere that two or more cables have to be run along the same path.

7. Use the screwdriver tip to remove one of the knockouts from a junction box on the side where the cable will need to enter the box. Run the cable into the junction box and leave the excess hanging. Repeat for each outlet, switch, fixture and appliance.

8. Call a licensed electrician to check the work you did and to wire the cables into the breaker panel and supply the power to the home.

Tips & Warnings

• Keep a circuit's load to 80 percent of its capacity or less. Run more circuits if you need them.

• For appliances, use 12-gauge nonmetallic cable that is rated to carry 20 amps. For lighting circuits, use two-conductor 14-gauge nonmetallic cable rated for 15 amps. An electric stove will need 6-gauge three-conductor service-entrance round cable that is rated for 50 amps and needs to be on its own circuit.

• Electricity can be deadly so follow safety precautions and, if in doubt, call an electrician.

• Do not wire the cable into the breaker panel yourself. Leave that to the electrician, who will need to check a few things prior to supplying power to the new construction.

• If you're working in an existing structure, be sure that no electricity is coming into the home. You won't be touching the breaker panel but you might come into contact with existing wiring so be sure there is no current.

References

• "Kitchen Renovations"; Time Life Books; 1998
• New Complete Do-It-Yourself Manual; Reader's Digest; 1991
• "New Living Spaces"; Time Life Books; 1977
• Holmes: The Magazine to Make it Right; Mike Holmes; December 2010