The advent of the twist-lock plug revolutionized the safety and reliability of high-amperage extension cable connections in commercial and industrial applications. Twist-lock connector plugs are also used on lower capacity extension cords, and as power supply connector plug-ins on various types of electrical equipment.

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You can use a 30-amp twist lock plug for either a 240-volt supply or a 120-volt application. Installation normally takes about 30 minutes, and requires a minimal amount of tools and experience.

Step 1

Turn the screws in the plug contact end of the twist-lock assembly counterclockwise, until they are loose from the outside cover. The screws will free themselves from the cover, but will not come completely out of the assembly.

Step 2

Remove the outside cover and set it aside.

Step 3

Use the wire strippers to strip the sheathing from each of the conductors to the point recommended by the twist-lock plug manufacturer. All the conductors should be of equal length. Their colors will be green, black and white.

Step 4

Place the twist-lock outer cover over the cable, with the open plug-end facing the tips of the conductors.

Step 5

Insert the conductors through the rear of the twist-lock assembly.

Step 6

Insert the green conductor into the green receptacle behind its plug tip. Make sure the tip is fully seated up to the shoulder of the sheathing.

Step 7

Insert the white conductor into the white receptacle behind its plug tip. Make sure the tip is fully seated up to the shoulder of the sheathing.

Step 8

Insert the black conductor into the black receptacle behind its plug tip. Make sure the tip is fully seated up to the shoulder of the sheathing.

Step 9

Slide the twist-lock outer cover forward over the assembly.

Step 10

Tighten the cover screws using the appropriate screwdriver, taking care not to tighten them too much. Be certain that each screw is fully seated.

Step 11

Tighten the cable clamp at the rear of the twist-lock plug, using the screwdriver to secure the cable inside it. Make sure it has a firm hold of the cable's outer jacket.