How to Splice a Cat5 Cable

By M.L. Browne

A Category 5, or Cat5, cable is composed of a set of four twisted pairs of smaller cables that transmit and receive signals encased in a flexible plastic jacket. Cat5 cables provide Ethernet connections among computers, network routers and hubs at speeds up to 100 megabits per second and to distances of up to 100 meters. Commercial vendors sell Cat5 cables in reels so the cable can be cut to size as well as in pre-cut lengths that work for most computer networking needs. The twisted pair wires are color-coded so they can be properly terminated in RJ-45 terminals. If an existing Cat5 cable needs to be lengthened, it can be spliced with an additional length of cable.

Things You'll Need

  • Wire cutters or razor utility knife
  • Wire stripper tool
  • Tape measure
  • Electrical tape
  • Length of Cat5 cable

Step 1

Measure the existing cable length and subtract it from the connection distance to determine how much much splice cable to cut.

Step 2

Measure and cut a length of Cat5 cable to a length slightly greater than your splicing measurement and then remove about a half-inch of the cable jacket on either end.

Step 3

Cut the terminated cable (RJ45 jacks on either end) in half and remove about a half-inch of the cable jacket on either side of the cut.

Step 4

Separate the four twisted pairs (eight wires, four pairs in white/green, white/orange, white/blue, white/brown) at the cut ends of each cable.

Step 5

Use the wire stripper or a razor utility knife to remove a quarter-inch of the wire shielding for all of the cables. Take care to keep the wire pairings intact.

Step 6

Twist each wire at both ends of the splice cable to the corresponding wire in the two cut cables (blue to blue, green to green and so on) and wrap each exposed wire connection with a piece of electrical tape.

Step 7

Wrap electrical tape around the Cat5 cable at the splice points to finish the splice.

Tips & Warnings

  • Splicing may reduce the cable's overall integrity or performance. If you notice excessive transmission activity, consider replacing the Cat5 cable entirely.
  • Never use a spliced cable in a location where it can get wet.