Step 1: Pick up parts and apply for a permit
Surface wiring is a system of channels and boxes that let you put outlets, switches or light fixtures anywhere you want—without the hassle of cutting into walls, fishing wire and patching holes. And it can look neater than you might think, since you can paint the parts to match the walls. Mount outlets low on walls where they'll be hidden by furniture.
All the parts you need are available in metal or plastic at home centers. We chose plastic because the channel was easier to cut. You'll also need wire, connectors, outlets and cover plates. (You can use a similar system to run low-voltage wiring for a telephone, TV or computer.)
You'll need some wiring know-how to complete this job safely. You can usually add outlets to an existing circuit unless you plan to plug in a device that draws a lot of power, such as an air conditioner or a space heater. Your electrical inspector will review this with you when you apply for a permit. Be sure to have your work inspected when it's complete.
Step 2: Assemble the channel and boxes
Start by mounting a box base at an existing outlet (Photo 1). You'll later draw power from that outlet to serve the new outlets. Cut out the back panel of the box with a utility knife before you screw it to the junction box. Then use a stud finder to locate studs and mark them with masking tape.
Run channel to the first outlet location (Photo 2). If the channel won't make any turns or run around corners, just cut it to length with a hacksaw. But if the channel turns up or down or goes around a corner, miter the adjoining ends at a 45-degree angle. A power miter saw will do this fast, although you can also use a miter box to guide a hacksaw blade ($7 at home centers and hardware stores). To mount the channel base, drill 1/8-in. holes at each stud and 1/2 in. from the ends. Wherever an end doesn't land on a stud, use a drywall anchor.
With the first section of channel in place, fasten a box base to the wall. Don't cut out the back panel. If the base lands on a stud, simply screw it to the stud. If not, use two drywall anchors. Continue adding channel and boxes.
Figure A: Surface Wiring PartsSurface wiring can extend from the existing junction box in one direction (as in our photos) or in two or three directions. It can run around corners or up and down walls.
Note: You can download Figure A and enlarge it in the Addendum below.
Wiring at existing outlet
Figure B: Wiring at Existing OutletIn general, join all hot wires, all neutral wires and all ground wires and add pigtails to the proper terminals on the outlet.
Note: You can download Figure B and enlarge it in the Addendum below.
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Step 3: Install the wiring
Next, run wire from the existing junction box to each box base. The size of the wire you add must match the size of the existing wire. Use the labeled notches on a wire stripper to check the gauge of the existing wire (14-gauge is most common, but you may have 12-gauge wire).Use only individual wires labeled “THHN,” which is sold in spools or by the foot at home centers and hardware stores. You'll need three colors: green for the ground, white for the neutral, and red or black for the hot wire. Don't simply buy plastic-sheathed cable and run it inside the channel.
Cut channel covers to length (no need to miter them). At turns or corners, hold an elbow in place when you measure for the covers—the elbow will overlap about 1/4 in. of the cover. Snap the covers onto the channel base followed by the elbows and boxes (Photo 3).Wiring the outlets is similar, whether you added several outlets or only one. If you ran two channels from the existing junction box (as in Figure A), you'll have two new sets of wire to connect to the old wiring (Figure B). If you ran channel only one direction from the box (as in our photos), you'll have fewer wires, but the process is the same: Join all the hot wires together, all the neutrals together and all the grounds together. Wiring is similar at the new outlet boxes that fall between sections of channel (Photo 3 shows “pigtails” ready for an outlet). At the last box in the run, you'll have only three wires (see Figure A); connect them directly to the new outlet.
When you remove the old outlet, check the color of the bare wire ends. If they're gray rather than dull brown, they're made of aluminum rather than copper. Call in a licensed electrician to connect the old aluminum wires to the new copper wires.