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Field guide · Cabling & termination

110 block

The two-stage termination that confuses people the first time: conductors lay into the base in colour order, then a four- or five-pair connecting block presses over them and seats every contact at once. Covers lay-in order, connecting block sizes, and how the cross-connect is made on top.

Plate 01Diagram

Lay the pairs in, press the connecting block on.

Termination sequence
Jumper wire — 110 blade
Connecting block — not yet fitted
12345678
Index strip — wiring base

Conductors laid into the index strip in straight cable order, twist held right up to the strip, tails trimmed flush at the outer edge.

Lay-in order — straight cable order, striped conductor first
  1. 1white/blue
  2. 2blue
  3. 3white/orange
  4. 4orange
  5. 5white/green
  6. 6green
  7. 7white/brown
  8. 8brown

Note this is cable order, not T568A or T568B pin order. The block takes the pairs as they come out of the jacket — the jack or patch panel at the end of the run does the 568 translation.

Fig. 01The termination as four stages. The conductors are never punched individually — they lay into the index strip, and the connecting block pressed over them terminates all eight at once, then presents a second set of contacts on top for the cross-connect.
Plate 02Procedure

Doing it

Terminating a four-pair run onto a wall field, and leaving something the next person can read.

Tools
  • 110-blade punchdown tool
  • Connecting block seating tool
  • Toner and probe
Materials
  • 110 wiring base with legs
  • Four-pair or five-pair connecting blocks
  • Cat5e or Cat6 cable
  1. 01

    Mount the base and dress the cable to it

    Fix the wiring base to the backboard with its legs, route the cable up through the legs, and bring each four-pair out at the index strip it will terminate on. Dress before you strip — a base wired first and dressed afterwards never looks right again.

  2. 02

    Strip and lay the pairs in colour order

    Strip roughly two inches of jacket and lay the conductors into the index strip in straight cable order: white/blue, blue, white/orange, orange, white/green, green, white/brown, brown. This is cable order, not 568 pin order — the jack or panel does that translation elsewhere.

    CautionKeep the twist right up to the index strip. This is where the crosstalk measurement is won or lost.

  3. 03

    Trim the tails flush

    Cut each conductor off at the outer edge of the index strip. Long tails prevent the connecting block from seating square, and a connecting block that is not square is a row of intermittent contacts.

  4. 04

    Press the connecting block home

    Set the four- or five-pair connecting block over the laid-in conductors and drive it down with the seating tool or the impact tool's blockless head. It terminates all eight conductors in one motion and holds them under constant pressure.

  5. 05

    Cross-connect on top of the block

    The connecting block presents a second set of contacts on its upper face. Jumper wire punched here — with a 110 blade — is how circuits are patched. Every change happens on the jumper, never on the cable underneath.

  6. 06

    Label and certify

    Number the index strip, record what lands where, and wire-map every position. The labelling is what makes the field usable; the certification is what makes it warrantable.

Plate 03Questions
Questions people actually ask
What is the difference between a 66 block and a 110 block?
A 66 block terminates one conductor per contact with a direct punch, and tops out around Cat3. A 110 block lays conductors into a base and seats them under a connecting block, holds a much tighter geometry, and is rated to Cat6. Use 110 for data, 66 only for legacy telephone.
What order do the wires go on a 110 block?
Straight cable order, striped conductor first: white/blue, blue, white/orange, orange, white/green, green, white/brown, brown. That is not the same as T568A or T568B pin order — the block takes the pairs as they leave the jacket.
What is the difference between a four-pair and five-pair connecting block?
Only the number of pairs each one terminates. Four-pair blocks align with a single Cat5e or Cat6 run and are the normal choice for data; five-pair blocks align with the 25-pair binder groups used in telephone distribution.
Do I punch the connecting block down with the same tool?
The conductors need no individual punching — seating the connecting block terminates them all. You need the impact tool with a 110 blade for the jumper wire that goes on top of the block afterwards.
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