Step 1
Cut off both ends of the extension cord with the wire cutter. Disassemble the 250-volt plug by removing the two screws that hold it together. Determine how much sheathing on the extension cord to remove and cut it off with the wire stripper. Only remove as much sheathing as necessary. The sheathing should fit into the plug's strain relief and end just before the wires attach to the terminals.
Step 2
Strip 5/8 inches of insulation from the ends of all three wires and gently twist the strands on each wire. Loosen the three terminals with a screwdriver. Insert the stripped wire ends into the plug through the strain relief.
Step 3
Wrap the green ground wire around the ground terminal clockwise. Tighten the ground terminal firmly. Ensure no loose strands of wire are free to move around inside the plug.
Step 4
Wrap the remaining two wires clockwise around the two terminals. The order does not matter. Tighten the terminal screws firmly.
Step 5
Reassemble the plug with the two screws. Tighten the strain relief to securely hold the cord in place, but not so tight that it crushes the cord. Repeat all these steps at the opposite end of the cord with the receptacle.