A 110 block is a type of punch-down block used to terminate runs of

on-premises wiring On-premises wiring (customer premises wiring) is customer-owned transmission or distribution lines. The transmission lines may be metallic (copper) or optical fiber, and may be installed within or between buildings. Premises wiring may consis ...

in a

structured cabling In telecommunications, structured cabling is building or campus cabling infrastructure that consists of a number of standardized smaller elements (hence structured) called subsystems. Structured cabling components include twisted pair and opt ...

system. The designation ''110'' is also used to describe a type of insulation displacement contact (IDC) connector used to terminate twisted pair cables, which uses a punch-down tool similar to the type used for the older 66 block.

Usage

Telephone distribution

Early residential telephone systems used simple screw terminals to join cables to sockets in a

tree topology A tree topology, or star-bus topology, is a hybrid network topology in which star networks are interconnected via bus networks. Tree networks are hierarchical, and each node can have an arbitrary number of child nodes. Regular tree networks A ...

. These screw-terminal blocks have been slowly replaced by 110 blocks and connectors. Modern homes usually have phone service entering the house to a single 110 block, whence it is distributed by

to outlet boxes throughout the home in

star topology A star network is an implementation of a spoke–hub distribution paradigm in computer networks. In a star network, every host is connected to a central hub. In its simplest form, one central hub acts as a conduit to transmit messages. The ...

. At the outlet box, cables are attached to ports with insulation-displacement contacts (IDCs), and those ports fit into special faceplates. In commercial settings, this style of ''home run'' or

wiring was already in use on 66 blocks in telecom closets and switchrooms. The 110 block has been slowly replacing the 66 block, especially for data communications usage.

Computer networks

The 110 style insulation-displacement connection is often used at both ends of

networking cable Networking cable is a piece of networking hardware used to connect one network device to other network devices or to connect two or more computers to share devices such as printer (computing), printers or Image scanner, scanners. Different types o ...

s such as Category 5, Category 5e, Category 6, and Category 6A cables which run through buildings, as shown in the image. In switch rooms, 110 blocks are often built into the backs of

patch panel A patch panel is a device or unit featuring a number of jacks, usually of the same or similar type, for the use of connecting and routing circuits for monitoring, interconnecting, and testing circuits in a convenient, flexible manner. Patch ...

s to terminate cable runs. At the other end, 110 connections may be used with

keystone module A keystone module is a standardized snap-in package for mounting a variety of low-voltage electrical Jack (connector), jacks or optical connectors into a keystone wall plate, face plate, surface-mount box, or a patch panel. Keystone modules hav ...

s that are attached to wall plates. 110 blocks are preferred over 66 blocks in high-speed networks because they introduce less

crosstalk In electronics, crosstalk (XT) is a phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, ...

and many are certified for use in Category 5, Category 6 and Category 6A wiring systems. Individual Category 5e and better-rated 8P8C jacks (keystone and patch panel) with IDC connectors commonly use the same punchdown 'teeth' dimensions and tools as a full size 110 block.

Advantages

110 style blocks allow a much higher density of terminations in a given space than older style termination blocks (66 style or wire wrap) because of their stacking capability. Some 110 blocks meet specifications for higher bandwidth data protocols such as Category 5 and higher.

Problems

During regular usage, very small pieces of insulation can become stuck inside the 110 block contacts; this renders that given pair unreliable or unusable, until the pieces are removed. A tool known as a spudger can be used to remove excess insulation pieces. The wire hook which comes with many punch down tools can also be used to remove wire pieces. A new wire inserted over an existing insulation remnant may be unreliable, as the 110 IDC was designed to hold only a single wire per contact. For testing it is more difficult to reliably connect to a working circuit on a 110 block than on older style blocks. The circuit must be broken, or insulation displacing contacts may be used on jumper wires. Repeated use of insulation displacing contacts may lead to a difficult-to-locate broken or intermittently-failing jumper wire.

References