A NEMA 6-15 plug has two horizontally-aligned straight-blade prongs and one horseshoe-shaped prong. A 6-15 plug's prong shape and spacing only fits into a NEMA 6-15 receptacle. The horseshoe-shaped prong pushes into the receptacle's ground terminal and the 6-15's horizontal prongs slide into the receptacle's hot slots. A NEMA 6-15 plug, considered a 15-amp 250-volt 2-pole 3-wire grounded plug, often supplies electricity to window-mounted air conditioners and some commercial office equipment. A NEMA 6-15 plug usually connects to its electrical device with 14-gauge wires.
Remove the last 3/8 inch of the insulation from the end of each wire entering the NEMA 6-15 plug with wire strippers. Some wire sets use three insulated wires — usually black, white and green colored — and some use two insulated wires — usually white and black colored — with an additional uninsulated wire.
Grip the middle of the stripped portion of each wire with a pair of pliers. Form the end of the wire into a hook shape.
Loosen the three NEMA 6-15 plug's wire terminal screws with a Phillips screwdriver. A NEMA 6-15 plug uses a green screw and the letter "G," found stamped into the plug's body, to identify the ground terminal. The two unlabeled wire terminals connect to the live wires.
Slip the ground wire's hook over the NEMA 6-15 plug's ground terminal screw, then tighten the terminal screw. The ground wire, the green or uninsulated wire, protects the appliance's user from accidental electrocution.
Slip one of the hot wire's hooks over one of the NEMA 6-15 plug's hot terminal screws. Tighten the 6-15 plug's terminal screw. The two interchangeable hot wires in a 2-wire 250-volt electric circuit usually use black and white insulation, but sometimes use black and red insulation instead.
Slip the remaining hot wire over the last NEMA 6-15 plug's terminal. Tighten the 6-15 plug's terminal screw.