Wiring a Category 5 66 block

Sept. 1, 1995
Wiring a 66 block with Category 5 unshielded twisted-pair cable requires a different termination method not typically used with voice-grade cables.

Robert Y. Faber, Jr.


Valerie Smith


The Siemon Co.


Wiring a 66 block with Category 5 unshielded twisted-pair cable requires a different termination method not typically used with voice-grade cables.


The following procedure will help ensure that the pair untwist of any twisted pair of conductors will be less than or equal to the 0.5-inch requirement of the Telecommunications Industry Association/Electronic Industries Association 568A standard.


1) Mount the 66-style block`s bracket on a properly prepared plywood wall surface or a crossconnect frame. This bracket is useful for cable management and slack storage.

2) Route the cables through the bracket and distribute them evenly to the left and right sides--for example, six 4-pair cables per side.

3) Snap the 66-style connecting block onto the bracket.

4) Remove only as much cable jacket as necessary to terminate the cable conductors. Remember to leave some cable slack behind the block and bracket for future reterminations.

5) Dress the cable pairs through the fanning-strip slots as pairs. Both conductors of each pair should be inserted through the same slot in the fanning strip.

6) Once the conductors are inside the block`s fanning strip, split the two apart and terminate them onto the clips. Be careful not to untwist the cable pairs more than 0.5 inch for Category 5 cables (and no more than 1.0 inch for Category 4 cables).

7) When dressing cable pairs through the fanning strips, alternate slots so that the first pair is pulled through the first slot. Skip the second slot, and pull the second pair through the third slot, and so on. The alternate, empty slots may be used for crossconnect wire.

8) Inspect the cable pairs before terminating.

9) Terminate the conductors using an automatic impact tool. Less expensive nonimpact tools are also available.

10) Labeling may be done on the connecting-block fanning strips, add-on designation strips or cover.

Robert Y. Faber, Jr., RCDD, is a corporate trainer.

Valerie Smith, EE, is an electrical engineer at The Siemon Co., Watertown, CT.

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