Definition: punch block

A type of terminal strip used to connect telephone or data lines to each other. Also called "punch-down block," "quick-connect block," "terminating block" and "connecting block," punch blocks use "insulation displacement connectors" (IDCs), which cut through the insulation as the wire is pushed into them with a punch down tool.

The most common punch blocks are the 66 and 110 blocks. The 66 block has been widely used for splicing 25 pairs of telephone wires together. Evolving from the 66 block for voice is the 110 block for data, which is made up of rows of four IDCs that are used to splice pairs together. There are also 110 blocks that connect a punched down wire on one side to preconnected patch cords with connectors such as RJ-45 or Telco 50-pin on the other side.

A 66 Punch Block

Each row of a 66 block is set up for one pair of wires to be spliced to another pair; however, any pair of clips can be used to connect any two wires.