How-To Electrical
transparent transparent



Trans 1) Getting Started Trans
2) Electrical System Basics
3) Service Panel
4) Running Cable
5) Outlets
6) Switches
7) Installing Light Fixtures
8) Common Electrical Codes
9) Replacing Switches & Outlets
10) Repairing Lamps & Cords
11) Glossary

Running Cable

pushing cable through holes in wall studsRunning electrical cable is simple in theory: pull it through holes in the framing from a junction box to the service panel.
However, actually getting cable to cooperate can be difficult and time consuming. So it helps to apply some creativity and patience.

Double-check with your circuit diagrams before running any cable. Also see if you can double up runs anywhere by pulling two cables at once.

In a new house or a major remodeling project, cable and boxes are "roughed-in" before the walls are insulated and drywalled.

NOTE: Insulation can be put up then removed for an inspection, but inspecting needs to be done before the walls are sealed by a vapor barrier and wallboard.


mounting junction boxHanging Boxes & Drilling Holes

Mount junction boxes for the outlets, lights and switches. Each box should stick out a little past the framing so its front will be flush with -- or set back just a fraction from -- the drywall.

You can use a scrap piece of drywall to set boxes out the right distance. Some boxes even have a pre-formed 1/2" reference line for quick installation.

Next, drill holes in the framing for the cables. Most rooms have an attic above them or a basement below. Drilling holes so cable runs horizontally through joists is usually easiest.

Drilling 1 1/4" holeA heavy-duty right-angle drill with a 1" bit is a good tool of choice. Wall holes drilled at about knee-height will be just right.

Codes require that holes be 1 1/4" from both edges of studs which puts them right in the middle of a 2 x 4.

Where lines are too close to framing edges, add protective metal cover plates to prevent nails from puncturing wires and pipes.

Drilling holes through ceiling joists and wall plates will be a bit harder and that's where the right-angle drill is really handy.



Pulling Cable

pulling cable through studThe traditional way to pull cable is to start at the last fixture in the run, pull cable to each fixture in the circuit, and continue all the way back to the service panel.

To do this, leave the box/spool of cable at the last fixture, unwind enough cable to complete the run and then start pulling it through the holes.

Nonmetallic-sheathed cable is used most of the time. It can tangle or bind once in a while. If you feel a lot of resistance while pulling, the cable is probably kinked and needs to be straightened out somewhere along the run.

If you're replacing old cable, you can often twist the ends of new and old wires together, wrap them with electrical tape, and pull the old cable out of the wall until the new cable appears.

using fish tape to run cableA special tool called a "fish tape" can also be fed through holes, hooked to new cable, and pulled back to retrieve it.

Each time you reach a junction box, pull a couple extra feet of cable through for making connections later.

On long runs, you may have to go back to the box/spool a few times to feed more cable through. That's when two people really save time: one feeding cable and one pulling cable.

Once the cable reaches the service panel, leave a foot or so of extra length on both the service end and the box/spool end for connecting.

labelling cablesAfter the cable is in place, fasten it to framing with brackets -- called staples -- every 4 1/2', at turns, and where cable enters a box.

Also label each cable end with a felt pen or piece of tape to keep them organized.

Remember, when the rough-in is done an inspection is needed, so schedule it accordingly to avoid downtime.

After the inspection, drywall and paint, you're ready to install the switches, outlets and light fixtures.

Previous Next