How to Tie a UL Knot for Lamp Socket Wiring Repair

Tying an Underwriter's knot in cord wires during lamp socket repair is a safety measure.

A UL knot tied in lamp socket wiring adds to safety.A UL knot tied in lamp socket wiring adds to safety.
The knot absorbs tension and keep socket wiring securely connected under the terminal screws, preventing short circuiting if the cord is jerked suddenly or placed under strain.

Unplug the lamp and remove the lampshade and light bulb. Use a work space with good lighting.

Follow the replacement socket kit's instructions for removing the cord wires from the old lamp socket. Cut the lamp cord's wire ends with scissors or a wire cutter to remove damaged or blackened ends of wires previously screwed into the socket.

Snap the replacement socket shell apart from the socket and cap by squeezing at the word "Press." Insert the lamp cord wire through bottom of the cap. Screw the cap into place on the lamp.

Cut the wires in the lamp cord down two to three inches with a knife between the wires. Use the knife or a wire stripper to remove about 1/2 inch of the covering to expose the metal strands.

Hold the wires so that both point upward and separate them into a V shape.

Bend the V's left-side wire to the left to begin one loop of the UL knot's figure-8 shape. Continue bending downward, then to the right behind the unspliced portion of the lamp's cord. The wire's end should extend an inch past the beginning point of the loop. Hold it in place with your left thumb and index finger.

Bend the V's right wire to the right and downward behind the left loop's extended end, then in front of the unspliced wire. Thread the right loop wire's end through the left loop. Pull both ends to finish the Underwriter's knot.

Loosen the socket's terminal screws with a screwdriver.

Twist each wire's strands tightly for ease in wrapping around the screws. The black or smooth wire (also known as the "hot" wire) goes to the yellow or gold terminal screw. The white or ribbed neutral wire goes to the other screw, often silver in color.

Connect each wire to its terminal post by wrapping the wire clockwise 3/4 around the screw. Tighten securely with a screwdriver.

Slide the shell over the socket and snap it back into the cap to complete the installation. Replace the light bulb and lampshade.

Things You Will Need

  • Wire cutter
  • Wire stripper

About the Author

Jackie Dunn Wiehe began in 1975 as writer, editor and photographer for the "Bolivar Herald-Free Press" in Missouri. She received several state press awards, including Missouri Press Women's 1977 Communicator of the Year. She has written for and edited newsletters for Missouri businesses and education groups. She holds a Master of Science in higher and adult education from the University of Missouri-Columbia.