66 block
Encyclopedia
Punch block
A punch down block is a type of electrical connection often used in telephony. It is named because the solid copper wires are "punched down" into short open-ended slots which are a type of insulation-displacement connectors...
used to connect sets of wires in a telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
system. 66 blocks are designed to terminate 22 through 26 AWG
American wire gauge
American wire gauge , also known as the Brown & Sharpe wire gauge, is a standardized wire gauge system used since 1857 predominantly in the United States and Canada for the diameters of round, solid, nonferrous, electrically conducting wire...
solid copper wire.
The 25-pair standard non-split 66 Block contains 50 rows; each row has four columns of clips that are electrically bonded.
The 25-pair "Split 50" 66 Block is the industry standard for easy termination of voice cabling, and is a standard network termination by telephone companies–generally on commercial properties. Each row contains four clips, but the left two clips are electrically isolated from the right two clips.
66 blocks pre-assembled with an RJ-21 female connector are available that accept a quick connection to a 25-pair cable with a male end. These connections are typically made between the block and the CPE (customer premise equipment
Customer-premises equipment
Customer-premises equipment or customer-provided equipment is any terminal and associated equipment located at a subscriber's premises and connected with a carrier's telecommunication channel at the demarcation point...
).
Use
Circuit pairs are connected to the block with a punch-down tool by terminating the tip wire on the leftmost slot of one row and ring wire on the leftmost slot of the row beneath the mating tip wire. Typically, a 25-pair cable coming from the phone company is punched down on the left side of the block in pairs. The right hand side of the block is wired to the customer premise equipment (CPE) with jumper wires. Bridging clips are used to connect the two center terminals, connecting the left-hand side of a split block with its right-hand side, thus completing the circuit. The clips form the point of interface between the subscriber and the provider. The bridging clips can be easily removed by either the subscriber or phone company personnel for trouble isolation, allowing the ability to split a circuit and determine in which direction trouble may exist. An orange insulating cover attached to a 66 block denotes its designation as a demarcation pointDemarcation point
In telephony, the demarcation point is the point at which the public switched telephone network ends and connects with the customer's on-premises wiring. It is the dividing line which determines who is responsible for installation and maintenance of wiring and equipment -- customer/subscriber, or...
by the local exchange carrier
Local exchange carrier
Local Exchange Carrier is a regulatory term in telecommunications for the local telephone company.In the United States, wireline telephone companies are divided into two large categories: long distance and local...
.
Currently, 66 blocks are considered legacy devices. Compared to more contemporary wire terminating devices they are physically large, and because of their maximum 16 MHz Category 3
Category 3 cable
Category 3 cable, commonly known as Cat 3 or station wire, is an unshielded twisted pair cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz...
signaling compatibility, they are ill suited for high speed data circuits faster than 10BASE-T
10BASE-T
Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. Other Ethernet cable standards employ coaxial cable or optical fiber. Early versions developed in the 1980s included StarLAN followed by 10BASE-T. By the 1990s, fast, inexpensive...
. However, there are special Cat5e Certified 66 blocks available from manufacturers such as Siemon which meet all standards for Cat5e termination.
'Split 50' 66 blocks are still used as network interface blocks in distribution frame
Distribution frame
In telecommunications, a distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made.For example, the Main Distribution Frame located at a telephone central office terminates the cables leading to subscribers on the one hand, and cables leading to...
s to interconnect circuits with bridging clips, but are primarily limited to narrowband
Narrowband
In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum.The opposite of...
circuits such as POTS
Plain old telephone service
Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
/DSL, DS0, or DS1 circuits.
Modern 110 block
110 block
A 110 block is a type of punch block used to connect sets of wires in a structured cabling system. 110 is also used to describe a type of Insulation-displacement connector used to terminate twisted pair cables which uses a similar punch-down tool as the older 66 block...
s have largely supplanted 66 blocks in new installations because the newer termination is almost always Category 5 compliant, and capable of supporting 100 MHz or faster signaling.
See also
- The 110 block110 blockA 110 block is a type of punch block used to connect sets of wires in a structured cabling system. 110 is also used to describe a type of Insulation-displacement connector used to terminate twisted pair cables which uses a similar punch-down tool as the older 66 block...
is a similar device that serves the same purpose - The 25-pair color code25-pair color codeThe 25-pair color code is a color code used to identify individual conductors in a kind of electrical telecommunication wiring for indoor use, known as twisted pair cables . The colors are applied to the insulation that covers each conductor...
is used to identify individual pairs within a 25-pair cable - The cross connect point is an Insulation-displacement connectorInsulation-displacement connectorAn Insulation-displacement connector, insulation-displacement technology/termination or insulation-piercing connector is an electrical connector designed to be connected to the conductor of an insulated wire or cable by a connection process which forces a selectively sharpened blade or blades...