Things You'll Need
American Wire Gauge (AWG) 12, Black, solid copper wire
AWG 12, White, solid copper wire
AWG 12, Bare, solid copper wire
3 20-Ampere, 120-volt duplex receptacles
Diagonal pliers/wire cutters
Lineman's pliers/electrician's pliers
Needle nose pliers
3-gang receptacle cover
Black plastic electrical tape
Wiring a 3-gang receptacle box is a relatively easy project that almost anyone can do successfully the first time. A 3-gang receptacle box is usually made of metal or Acrylonitrile butadiene styrene (ABS) plastic. The ABS plastic gang boxes are becoming more popular with remodelers since they are easier to install in finished walls. A 3-gang receptacle box may be the only box on a branch circuit or one of many receptacle boxes. In any case, the wiring is the same.
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Cut two 6-inch lengths of black and two 6-inch lengths of white insulated copper wire using the diagonal pliers. With the wire strippers, remove 3/4 inch of insulation from each end of these wires. When using the wire stripper, be careful to not nick of groove the bare copper conductors, as nicking or grooving will weaken them as well as increase resistance to the flow of electric current. If you do damage a conductor while stripping, throw it away and start over with a new wire.
Using the needle nose pliers, make loops in the stripped ends of these conductors. Using the white wires, connect one of the silver-colored neutral screws of the first receptacle to one of the neutral screws on the second receptacle. Use the second white wire to connect the second neutral screw on the second receptacle to one of the neutral screws on the third receptacle. Place the loops around the terminal screws in a clockwise direction and tighten the screws down snugly, but don't overtighten.
Repeat step two. This time use the short, black wires to connect the "Hot," brass-colored screws of the receptacles together.
Cut three 6-inch lengths of bare copper wire and make a four-way pigtail splice with the bare copper conductor entering the gang box. Place the ends side by side and twist tightly together in a clockwise direction using the electrician's pliers. Once twisted together, screw a wire nut in place over the twisted ends.
Make loops in the ends of the bare pigtail leads and secure them to the dark green, octagon-shaped screws on each of the receptacles.
Connect the black wire bringing power into the gang box to the free brass screw on the first receptacle. Connect the white neutral wire coming into the gang box to the free silver neutral screw on the first receptacle. Never place more than one wire under any one screw. This is a direct violation of the National Electrical Code and both a safety and fire hazard.
Wrap the terminal screws with electrical tape and secure the receptacles in the box using the "captured" 6-32 screws.
Install cover plate.