Wire Stripper

From Wikipedia, the free encyclopedia

Opera Snapshot_2017-11-12_004824_en.wikipedia.org

1 Types
1.1 Manual
1.2 Automatic
1.3 Laser Wire Stripper
2 Gallery



A US-style simple manual wire stripper is a pair of opposing blades much like scissors or wire cutters. The addition of a center notch makes it easier to cut the insulation without cutting the wire. This type of wire stripper is used by rotating it around the insulation while applying pressure in order to make a cut around the insulation. since the insulation is not bonded to the wire, it then pulls easily off the end. This type of wire stripper can be used on wires of any size. Another type of manual wire stripper is very similar to the simple design previously mentioned, except this type has several notches of varying size. This allows the user to match the notch size to the wire size, thereby eliminating the need for twisting, but can only be used on wire sizes that approximately match one of the notches. Once the device is clamped on, the remainder of the wire can simply be pulled out, leaving the insulation behind.

European-style wire strippers look more like a notched pincer, with a grab that is adjusted with a screw.


The automatic wire stripper was first patented in 1915 by Stuart G. Wood of Brooklyn, NY. The design was refined by Herman Gerhard Jan Voogd of the Netherlands eliminating the awkward 4 bar mechanism taking on the general outline that it has kept since. Wood, now of Rockville IL, added reinforcements, replaceable blades, and blade stops in 1943 The 1943 design was also equipped to block the halves open after stripping to avoid crushing the freshly stripped wire as it returned to its rest position.

A second actuation released the mechanism to return to the rest position. The action was further refined by Wood and finally by Eugene D. Hindenburg of DeKalb, IL. The final refinement of the action shifted the sequence of operations so that the stripping blades opened before any other part of the mechanism began to return to the rest position while the clamping jaws retraced the sequence of operation, remaining closed until the handles were fully released.

When engaged, an automatic wire stripper first simultaneously grips the wire in one side and in the other side closes its shaped blades cutting the insulation around the conductor. After the sides have completed their strokes the two sides of the mechanism spread apart to push the cut tube of insulation from the end of the conductor.

To use it, one simply places the wire in the jaws at the cutting slot matching the size of the conductor and squeezes the handles together. This device allows even a novice to strip most wires very quickly. The automatic wire stripper’s cutter must be short, because it causes the jaws to twist, as described by Wood in the 1943 patent.

All wire strippers are inherently limited to those wire sizes the cutting jaw notches will accommodate. An automatic wire stripper’s short cutter limits it to fewer notches and a smaller range of wire sizes than most other types of wire strippers. The accuracy of the cutting blade opening determines the smallest conductor that can be reliably stripped. If the cutter opening is to small it will impinge on the conductor causing excess friction and more tension than the wire can withstand.

If the cutter opening is too large the tension required to tear the remaining annulus of uncut insulation may be greater than the wire can withstand. Some models have an adjustable grip tension, to adjust the clamping force of the gripping jaw. The knob below the jaw on the yellow automatic strippers in the image below is a grip tension adjustment. Although in principle applicable to wire of any size, automatic wire strippers that are widely available have cutters that can accommodate conductors in a range of sizes no larger than 8 AWG nor smaller than 26 AWG, but not the entire range.

Laser Wire Stripper

A laser wire stripper is a computer-controlled machine, much like a CNC router, which uses a laser to burn off the insulation of the wire. Laser wire stripping machines are used mostly for very fine gauge wires since they do not damage the conductor. A typical CO2 laser wire stripping machine should be capable of stripping the insulation from any size wire.



A simple US style manual wire stripper.


European style wire stripper.


European style wire stripper.


An automatic wire stripper.

Wiring Block Techniques and Tips

Important Wiring Block Concepts

One big advantage of using a block to connect telephone wiring is that it gives you a lot of options on how to configure the installation to meet your requirements. That makes it important to spend some time planning your installation for a configuration that best meets your current needs and allows for future requirements.

An important concept to understand when planning a block installation is that cables are attached to blocks as a “permanent” installation and signals are extended between cables using cross-connect jumper wires. The only “built in” electrical connectivity on a 66 block (specifically 66M1-50 blocks like those illustrated and offered for sale on this site) is between each outer punch lug and the inner punch lug next to it. The only “built in” electrical connectivity on a 110 block is between the top and bottom of each wire position of the c-clips. All connectivity between the cables attached to a block is established by installing cross-connect jumper wires. On 66 blocks, the cables are terminated on the outside row of punch lugs and cross-connects are made on the inner lugs. On 110 blocks, the cables are seated in the base of the block and held permanently in place using c-clips and cross-connects are made on the top of the c-clips. Beyond those concepts, how a block is configured is dictated by the particular installation.

Cables on a block are generally arranged in an order that corresponds to the flow of the signal:

  • Connections to the public network (e.g. cable from the NID)
  • Connections to central equipment (e.g. cable to a DSL splitter)
  • Connection to stations (e.g. inside wiring cables to jacks)
  • When practical, inside wiring cables are arranged in an order that corresponds to the location of the other end of the cable (e.g. by room or by floor)
  • On a 66 block, ease of using bridge clips and installing cross-connects, might dictate a particular configuration,such as installing the cables to the NID and a DSL splitter in the same rows on opposite sides of the block.

As little sheath as possible is removed from the cable and the twist of the pairs is preserved as much as possible. That will preserve the quality of the cable to reject interference. All pairs of cables are normally terminated, even if the current requirement only needs one or two pairs, because it would be impractical to re-terminate the cables if access to the other pairs was required in the future.

Both 66 and 110 blocks are equally suitable for telephone wiring. One is not really “better” than the other. Block type selection for telephone wiring is normally dictated by factors such as cost, pair capacity, available mounting space, matching block type with existing blocks, availability of tools, and preferences of the installer. When 110 blocks were first manufactured, they were preferred for data use, but newer 66 blocks maintain CAT5 or better standards when properly installed. Patch blocks/panels are now preferred for most data connections instead of standard wiring blocks, but when cables are to be used interchangeably for voice and data, use of wiring blocks is still a reliable practice.

Regardless of which block you decide on using, be sure to use the appropriate punchdown tool. Trying to use substitute tools such as pliers and screwdrivers will not create a reliable connection and can damage the block, preventing reliable connections even if an appropriate punchdown tool is used in the future.

66 Blocks


The photo at the right illustrates several techniques used for installation of a 66-block.

Mounting and Basic Cable Routing

Blocks should generally be mounted on a plywood back board for structural stability. (This is also true for 110 blocks.) A 12″x24″ piece of 3/4″ or 1/2″ plywood is ideal and may be available “pre-cut” at some “home improvement centers”. The back board should be at least 18″ wide to attach to two adjacent vertical wall studs (normally 16″ on center) for strength and a 24″ width allows some flexibility on lateral position. A height of 12″ allows enough vertical space for a block and wire management mushrooms. The 12″x24″ size also allows space for one or two blocks, plus space for mounting other items such as a DSL splitter and a small modem/router. Cables can be brought to the block from above or below (or both). Cables are routed out the side of the “type 89” bracket and to the side of the block.

Wire Management Mushrooms

Plastic wire management distribution posts, often called mushrooms, help control the cross-connect jumpers. This isn’t a major factor for a single block installation, but becomes very significant when multiple blocks are used.

Bridge Clips

Bridge clips are used in place of a cross-connect jumper to connect the left and right sides of the block. They can be very useful for quick repeated disconnect/reconnect for testing or to limit line access on a planned repeated basis. They can also reduce the complexity of jumpers required for an installation. The bridge clips in the photo at the right replace two jumpers (white/blue and white/orange) that would have gone over the top of the block. Another pair of bridge clips could have been used to replace the white/brown jumper that does go over the top.

This photo is of a block wired as described on the page DSL Splitter at the Hub except that bridge clips are used to connect pair 5 to pair 30 and pair 6 to pair 31, instead of jumpers over the top of the block. With the bridge clips in place, all jacks would have access to both line one and line two. By removing the first two bridge clips, the jacks connected to the cables on the left side of the block would only have access to line two. By removing the second two bridge clips, the jacks connected to the cables on the right side of the block would only have access to line one.

Wire Punchdown


Original 66-block design was for individual wires to be routed through the block’s comb one wire per comb slot, as shown on the right in these photos. Technology has evolved and it is now known that CAT5 and higher quality specification are better maintained by routing twisted pairs through one comb slot and then terminating the wires without untwisting the pair any more than necessary, as shown on the left in the photos. Fanning pairs into the block like this requires an adjustment for technicians used to the old method. It requires rotating the punchdown tool between punching the tip wire and punching the ring wire, so it takes a little more time than the old method. This new method is not necessary for CAT3 or lower quality cable. If you are terminating cable that will only be used for phone on a 66 block, you may use either method even if the cable is CAT5, since phone lines do not require the same specifications as high-speed data lines. Even if the cable will be used for modems or DSL, it is doubtful that the method of 66-block termination will have any impact on the speeds obtained. For Ethernet and other high-speed data connections, a 110-block is preferable, but this new method of 66-block termination should preserve CAT5 testing specifications.

110 Blocks


The information provided below may help you understand how you might want to configure your 110 block installation. However, the Siemon and Leviton installation instructions for 110-blocks do an excellent job of covering the basic mechanical process of 110-block installation and cable termination. I don’t believe it would serve any purpose for me to repeat the information it contains, so please refer to it also.

Additional 110-Block Wiring Information

The Leviton instruction refers to removing the block from the legs to facilitate routing cables to the block. Blocks for 50 pairs and 100 pairs may have permanently attached legs that can’t be removed as described. As noted in the Leviton instruction, removing the legs is not really necessary for these smaller blocks, since the block is not large enough to present problems routing the cables. This is a different matter in large commercial installations involving 300 pair blocks or a large field of 100 pair blocks, in which case removing the blocks from the legs can be a big help.

The Siemon instruction for 110-blocks describes routing cables through holes in the back of the block. Some blocks do not have these holes, in which case cables are routed around the edge of the block as described in the Leviton document. I don’t know of any significant advantage of having the holes. In large installations, some technicians won’t use the holes even if they are present, so that cables can be routed in a consistent manner even if some blocks are used that don’t have the holes.

Cables are normally routed into the trough between odd and even rows and covered with a label strip. Jumper cross connects are then routed in the trough that doesn’t have the label strip. When routing cables around the sides, there are two popular methods:
1) Route six cables from each side and terminate on the positions closest to that side, three on the upper row and three on the lower row.
2) Route six cables from the left and terminate on the upper row and six cables from the right and terminate on the lower row.
Either method is perfectly acceptable. You will find it useful to use one of these methods rather than attempting to bring all cables from one side, because it will be easier to nest the cables into the trough between the rows.

Creating a Bridge Instead of Using Daisy Chain Jumpers

The Leviton document describes “daisy chaining” jumper wires on a 110-block, but also notes that it is not a common practice. It’s not a common practice because 110-blocks are normally used to make connections between two cables on a one-to-one basis, such as connecting a PBX port to a single station cable or a Ethernet hub port to a cable for a LAN connection. Residential telephone is a one-to-many connection, not one-to-one. However, daisy chaining is rather awkward to install on a 110-block while attempting to maintain twist in the jumper wires. It is also prone to pulling loose due to incidental movement of the jumpers and is nearly impossible to change without completely replacing all of the cross-connects. An alternative is to create a 110-block “bridge” for the one-to-many connection and then run individual jumpers from the bridge to each station cable. A “bridge” provides multiple connections for one signal (sometimes referred to as a “bus”). The bridge is created by running a jumper wire through consecutive pair connections in the block base (as shown in the first graphic below) and then installing c-clips just like would be done for station cables (as shown in the second graphic below). A jumper is installed from the c-clip for the cable for the incoming signal (the NID or DSL splitter cable) to the bridge to put the signal on the bridge. The station cables are installed on the remainder of the block and cross-connects are then completed by running jumpers from the bridge to the cable c-clips (as shown in the third graphic below for the first three station cables). This avoids the problems associated with daisy-chain jumpers on a 110 block. This also looks a lot neater and won’t cause odd looks from experienced technicians casually observing your installation.

A 100 pair 110-block with a 4-pair cable to the NID will support a bridge (with 21 connections) for one line to 18 station cables (or a cable to a DSL splitter and 17 station cables as illustrated below).

This series of graphics illustrates the top two rows of a 110 block in progressive stages of a DSL installation with a single pair 21 position bridge:

  • The first graphic shows the cable from the NID terminated on the first four-pair position, with a c-clip in place and the wire pair that will form the bridge seated in the block base before the c-clips are installed.
  • The second graphic shows the c-clips installed for the bridge and the cable to the DSL splitter installed with the c-clip in place.
  • The third graphic shows the station cables, c-clips, and the cross-connect jumpers for the first three stations installed.

110-bridge (1)

To support two lines, you would need two bridges, one for each line, or a bridge with two pairs that alternate. Two separate bridges may be conceptually easier to understand, but it will probably be easier to install the cross-connect jumpers by using one two-pair bridge. See the photos and descriptions for the four-line configuration below for an illustration of this configuration concept.

A 100 pair 110-block with a 4-pair cable to the NID would actually support up to 15 station cables (or a cable to a DSL splitter and 14 station cables) plus 34 bridge positions (17 positions for two lines). That would require mixing cables and bridge positions on one or two rows (depending on how you configure the block), which might be a little visually confusing, but it would work. If you actually have 15 station cables, I would recommend you consider using a separate block for the cables and a four-wire bridge (see below), to allow for future expansion.

To support four lines, you would need four bridges or a bridge of four alternating pairs that spans two rows. A 100 pair 110-block configured as follows would support access four lines on 11 station cables:

  • Row 1: NID cable and five station cables
  • Row 2: six station cables
  • Row 3: first 13 pair positions, single pair bridge for line one (white/blue)
  • Row 4: first 13 pair positions, single pair bridge for line two (white/orange)
  • Row 3: last 12 pair positions, single pair bridge for line three (white/green)
  • Row 4: last 12 pair positions, single pair bridge for line four (white/brown)
  • Or Rows 3 and 4: a four-pair bridge that spans both rows

Refer to the photos below: These photos show the block described above to support four lines at 11 stations. The separate bridges in the first photo may initially seem to easier to understand, but the four-pair bridge that spans two rows makes it easier to install jumpers. With a four-pair bridge, it is also easier to alter the cross-connect for one cable without accidently disconnecting the jumpers to another cable.


Photo-1 110 Block


Photo-2 110 Block


Photo-3 110 Block


Photo-3 110 Block

  • The first photo above shows the NID cable and 11 station cables installed with the c-clips installed. It also shows how wires would be seated in the base to create four separate bridges.
  • The second photo shows the wires for the separate bridges removed and replaced with wires seated to create a four-pair bridge that spans rows 3 and four.
  • Items to note:
    • The wires extend from row three to row four in the first four pair positions.
    • The first pair (white/blue) is extended to the 25th pair position on row three to provide an additional access point for line one.
    • The second pair (white/orange) is extended to the 25th pair position on row four to provide an additional access point for line two.
    • The 25th position access points for lines one and two can be used to extend these lines to another block.
  • The third photo shows the bridge with the c-clips installed. Note that a C-5 clip is used at the end of each row.
  • The last photo shows the finished installation, with the cross-connect jumpers installed and the label strip in place.
  • Items to note:
    • The cross-connect jumpers are simply four-pair cable with the sheath removed.
    • Jumpers could be run from cables to any bridge position, but this arrangement is the most orderly and easiest for someone else to understand in the future.
    • The NID cable and station cables in row 1 (STA1-5) are cross-connected to the bridge location in row 4 (BRIDGE 7-12) using four-wire jumpers run left or right around the closest end of the block, maintaining the natural twist of the jumpers and jumper bundles. Enough slack is left to allow physically tracing the jumper between positions.
    • The station cables in row 2 (STA 6-11) are cross-connected to bridge locations in row 3 (BRIDGE 1-6) using individual short jumpers at each pair position that dip just slightly into the trough so that there is no tension on the connection. A very slight twist is maintained in the jumper.
    • This arrangement makes the line connections to all cables identical. If you want a different line configuration at any jack, the jumpers for that cable would be altered accordingly.
    • If four separate bridges were used, jumpers would have to be run from the cables to four different locations. This would be considerably more complicated.
    • Neatness and clear labeling help achieve an installation that is less likely to have undetected errors during installation and that is more easily understood by someone required to work with the installation in the future. A finished block should give the visual impression that it was well planned and correctly installed.

If there is a great probability of needing more than 11 stations in the future, a better option would be to start with two 100 pair blocks. Put the NID and all the stations on one block and put the bridges on the second block, one per row or four-pairs spanning all four rows using a method similar to the graphics and photos above for two rows. Using a separate block for the bridge also has the advantage that if there was ever a desire to install a PBX/Key telephone system, the station block would remain intact and the bridging block would just be removed and replaced with a new block with the cables to the telephone system ports.

If you have more than one line and more than 14 station cables, you might want to use a combination of bridging and daisy chain jumpers. The illustrations below shows how to bridge the cable coming from the NID, bridge one pair to connect the voice side of the line from a DSL splitter, and use daisy chain jumpers to connect lines one and two on up to 19 station cables (similar to the 66-block in the photo above and on the page DSL Splitter at the Hub). To bridge the cable from the NID as shown, it must be routed to the top of the block in a non-standard manner, so make sure to secure it to the leg of the block with cable ties to avoid having any of its wires break from movement. Also note that when creating a bridge by running pairs vertically, every attempt should be made to maintain the existing twist in the pairs. The farther wires are run parallel in straight lines, the more likely that cross-talk will occur between the pairs. This is not a major concern in wiring a block for voice, but does become more significant if the connections will be used for modems or DSL.


Removing C-Clips

C-clips are intended to be permanently attached to the base once installed. Ideally, you’ll carefully plan your configuration and take care during installation so that you don’t need to remove a c-clip. Don’t include removing c-clips as part of your future expansion plan.

f a spare positions are available, it is advisable to consider simply abandoning positions with c-clips that you might be thinking of removing. However, occasionally you might find that is just absolutely imperative to remove a c-clip.

It is possible to remove a c-clip from a 110 block, but it’s not very easy. It must be done very carefully to avoid breaking the block row and may damage the clip (which is simply discarded and replaced). Firmly grasp the center of the clip with a pair of pliers (“Channel-Lock” type slip-joint pliers work best). Gently tilt the clip down slightly to unlock the holes on the top of the clip from the “teeth” on the top of the block row.

While pulling back on the clip to keep the top from locking back in place, tilt the clip upward slightly to unlock the holes on the bottom of the clip from the “teeth” on the bottom of the block row. While doing this, don’t tilt the clip too far and bend/break the block base row structure.

Some people find it easiest to do this slowly and others prefer a “down-pull-up” jerking motion. Slow is probably best for learning. You will definitely want to avoid repeating this process at the same location, since the block base will become stressed and more likely to crack.

Also, the teeth on the base that hold the c-clip will tend to become damaged and not retain the c-clip properly. If you have a blank space on your block, attach a clip to the block without wires and use that clip to practice, since it is easier to remove a clip without wires attached.

This information should have provided you a good idea of techniques for using a 66-block or 110-block for residential telephone installations.


Punch Down Tool

From Wikipedia, the free encyclopedia


A punch down tool with interchangeable blades

A punch down tool, also called a punchdown tool or a krone tool (named after the KRONE LSA-PLUS connector), is a small hand tool used by telecommunication and network technicians. It is used for inserting wire into insulation-displacement connectors on punch down blocks, patch panels, keystone modules, and surface mount boxes (also known as biscuit jacks).

Description and Use


A punch down tool in use, terminating a twisted pair cable into a Cat5e receptacle

Most punch down tools are of the impact type, consisting of a handle, an internal spring mechanism, and a removable slotted blade. To use the punch down tool, a wire is pre-positioned into a slotted post on a punch block, and then the punch down tool is pressed down on top of the wire, over the post. Once the required pressure is reached, an internal spring is triggered, and the blade pushes the wire into the slot, simultaneously cutting the insulation and securing the wire. The tool blade does not cut through the wire insulation to make contact, but rather the sharp edges of the slot in the contact post itself slice through the insulation.

However, the punch down tool blade also is usually used to cut off excess wire, in the same operation as making the connection; this is done with a sharp edge of the punch down tool blade trapping the wire to be cut against the plastic punch block. If this cutoff feature is heavily used, the tool blade must be resharpened or replaced from time to time. Tool blades without the sharp edge are also available; these are used for continuing a wire through a slotted post to make connections with another slotted post (“daisy-chained” wiring).

For light-duty use, there are also less-expensive punch down tools with fixed blades and no impact mechanism. These low-cost tools are more time-consuming for making reliable connections, and can cause muscle fatigue when used for large numbers of connections.

To accommodate different connector types, 66, 110, BIX and krone blocks require different blades. Removable blades for 66 or 110 are almost always double-ended. Some blades have one end that only inserts the wire for daisy-chain wiring from post to post, and another end that inserts wire and trims the excess length for termination at a post. Other blades have a cutting 66 blade on one end and a cutting 110 blade on the other. Krone blades require a separate scissor-like mechanism for trimming the wire.

Crimp Connection

From Wikipedia, the free encyclopedia

A crimp connection is a type of solderless electrical connection.

Simple crimp connectors are typically used to terminate stranded wire. Specialised crimp connectors are also used, for example as signal connectors on coaxial cables in applications at high radio frequencies (VHF, UHF).

Simple Crimp Connectors

They fulfill numerous uses, including allowing the wires to be easily terminated to screw terminals, fast-on / quick-disconnect / spade-foot type terminals, wire splices, or various combinations of these. A tube-shaped connector with two crimps for splicing wires in-line is called a butt splice connector. Crimp-on connectors are attached by inserting the stripped end of a stranded wire into a portion of the connector, which is then mechanically deformed / compressed (crimped) tightly around the wire. The crimping is accomplished with special crimping pliers. A key idea behind crimped connectors is that the finished connection is gas-tight.

Crimped connections fulfill similar roles, and may be thought of similarly, to soldered connections. There are complex considerations for determining which type is appropriate – crimp connections are sometimes preferred for these reasons:

  • Easier, cheaper, or faster to reproduce reliable connections in large-scale production.
  • Fewer dangerous, toxic or harmful processes involved in achieving the connection (soldered connections require aggressive cleaning, high heat, and possibly toxic solders).
  • Potentially superior mechanical characteristics due to strain relief and lack of solder wicking.

Many classes of crimped connections exist. Some of the most common are:


  • Wire to be terminated is inserted into a cylindrical section of metal, then crimped, with the resultant shape somewhat of an oval.
  • To the layperson, perhaps the most common type. Readily available at retail (Radio Shack, Home Depot, Fry’s, etc.).


  • refers to the pre-crimp crimp section having a U or V shape
  • More robust connection than barrel-type and thus more common in industrial and automotive applications
  • Simpler to automate since wire can be laid in the un-crimped connector versus barrel which requires funneling the wire into the barrel to prevent strands from catching.
  • Types:
    • F crimp: Both wire and insulation (if optional insulation support is present) are crimped from U to B shape.
    • Weather-Pack/Metri-Pack: common brand-name crimp connectors designed for use in sealed housings. Wire is crimped from U to B shape, insulation from U to ‘O’ shape.

Specialised Crimp Connectors

Crimp connections are used typically to fix connectors, such as BNC connectors, to coaxial cables quickly, as an alternative to soldered connections. Typically the male connector is crimp-fitted to a cable, and the female attached, often using soldered connections, to a panel on equipment. A special power or manual tool is used to fit the connector. Wire strippers which strip outer jacket, shield braid, and inner insulation to the correct lengths in one operation are used to prepare the cable for crimping.

Broadband Over Power Lines

From Wikipedia, the free encyclopedia

Broadband over power lines (BPL) is a method of power line communication (PLC) that allows relatively high-speed digital data transmission over the public electric power distribution wiring. BPL uses higher frequencies, a wider frequency range and different technologies from other forms of power-line communications to provide high-rate communication over longer distances. BPL uses frequencies which are part of the radio spectrum allocated to over-the-air communication services therefore the prevention of interference to, and from, these services is a very important factor in designing BPL systems.

1 History
2 Implementation
2.1 Technical challenges
3 Deployments
4 Standards
5 Failure scenarios
6 Ultra-High-frequency (≥100 MHz)
7 Real Plug and Play Last Mile Communications System
8 Power-over-fiber


BPL is based on PLC technology developed as far back as 1914 by US telecommunications company AT&T. Electricity companies have been bundling radio frequency on the same line as electrical current to monitor the performance of their own power grids for years. More recently there have been attempts to implement access BPL, or the provision of internet services to customers via the grid. The prospect of BPL was predicted in 2004 to possibly motivate DSL and cable operators to more quickly serve rural communities.

The high level of attenuation (or data signal loss) from access BPL power cables had two critical effects: It limited bandwidth, and it attracted opposition from groups within the radio community.


Generally BPL is described as either In-House BPL to network machines within a building, or Access BPL which will carry broadband Internet using power lines and allow power companies to monitor power systems.

Because electric current and radio (data) signals vibrate at different frequencies they do not interfere with each other enough to significantly disrupt data transmission. This only works on low-voltage and medium-voltage cables. High-voltage cables do not vibrate at a consistent frequency, causing regular spikes which cancel the data signal and severely interrupt the transmission.

MV lines carry generally up to 100 kilovolts, over a few kilometres between the electricity distribution stations and pole-mounted transformers. Low voltage lines transmit a few hundred volts over a few hundreds of metres, usually from pole-mounted transformers into a home or business.

Typically modem couplers embed data signals on to MV lines at the substation, with extractors at the LV distribution transformer feeding power into a group of buildings.

BPL modems transmit in medium and high frequency (1.6 to 80 MHz electric carrier). The asymmetric speed in the modem is generally from 256 kbit/s to 2.7 Mbit/s. In the repeater situated in the meter room the speed is up to 45 Mbit/s and can be connected to 256 PLC modems. In the medium voltage stations, the speed from the head ends to the Internet is up to 135 Mbit/s. To connect to the Internet, utilities can use optical fiber backbone or wireless link.

Utility companies use frequencies below 490 kHz for their own data applications. Most BPL equipment was built to operate between 1.7 MHz and 30 MHz and occasionally up to 80 MHz.

Technical Challenges

Deployment of BPL has illustrated a number of fundamental challenges, the primary one being that power lines are inherently a very noisy environment. Every time a device turns on or off, it introduces a pop or click into the line. Switching power supplies often introduce noisy harmonics into the line. And unlike coaxial cable or twisted-pair, the wiring has no inherent noise rejection.

The second major issue is electromagnetic compatibility (EMC). The system was expected to use frequencies of 10 to 30 MHz in the high frequency (HF) range, used for decades by military, aeronautical, amateur radio, and by shortwave broadcasters. Power lines are unshielded and will act as antennas for the signals they carry, and they will cause interference to high frequency radio communications and broadcasting. In 2007, NATO Research and Technology Organisation released a report which concluded that widespread deployment of BPL may have a “possible detrimental effect upon military HF radio communications.”


There have been many attempts worldwide to implement access BPL, all which have indicated that BPL is not viable as a means of delivering broadband Internet access. This is because of two problems: limited reach, and low bandwidth which do not come close to matching ADSL, Wi-Fi, and even 3G mobile. World major providers have either limited their BPL deployments to low-bandwidth connected equipment via smart grids, or ceased BPL operations altogether.

Australia saw trials of access BPL between 2004 and 2007; but no active access BPL deployments appear to remain there.

In the UK, the BBC published the results of tests to detect interference from BPL installations.

In the US, in October 2004, the US Federal Communications Commission adopted rules to facilitate the deployment of “Access BPL”, the marketing term for Internet access service over power lines.

The technical rules are more liberal than those advanced by the US national amateur radio organization, the American Radio Relay League (ARRL), and other spectrum users, but include provisions that require BPL providers to investigate and correct any interference they cause.

One service was announced in 2004 for Ohio, Kentucky, and Indiana by Current Communications but they left the BPL business in 2008.

On August 3, 2006, FCC adopted a memorandum opinion and an order on broadband over power lines, giving the go-ahead to promote broadband service to all Americans. The order rejected calls from aviation, business, commercial, amateur radio and other sectors of spectrum users to limit or prohibit deployment until further study was completed. FCC chief Kevin Martin said that BPL “holds great promise as a ubiquitous broadband solution that would offer a viable alternative to cable, digital subscriber line, fiber, and wireless broadband solutions”.

In the US, International Broadband Electric Communications (IBEC), which had an ambitious plan to provide access BPL in the US, ceased BPL operations in January 2012.


IEEE 1901 is a standard for high speed (up to 500 Mbit/s at the physical layer) BPL. It uses transmission frequencies below 100 MHz. It is usable by all classes of BPL devices, including BPL devices used for the last mile connection (less than 1500m to the premises) to internet access services as well as BPL devices used within buildings for local area networks, smart grid, PLC applications.

Failure Scenarios

There are many ways in which the communication signal may have error introduced into it. Interference, cross chatter, some active devices, and some passive devices all introduce noise or attenuation into the signal. When error becomes significant the devices controlled by the unreliable signal may fail, become inoperative, or operate in an undesirable fashion.

  • Interference: Interference from nearby systems can cause signal degradation as the modem may not be able to determine a specific frequency among many signals in the same bandwidth.
  • Signal degradation by active devices: Devices such as relays, transistors, and rectifiers create noise in their respective systems, increasing the likelihood of signal degradation. Arc-fault circuit interrupter (AFCI) devices, required by some recent electrical codes for living spaces, may also attenuate the signals.
  • Signal attenuation by passive devices: Transformers and DC–DC converters attenuate the input frequency signal almost completely. “Bypass” devices become necessary for the signal to be passed on to the receiving node. A bypass device may consist of three stages, a filter in series with a protection stage and coupler, placed in parallel with the passive device.

Ultra-High-frequency (≥100 MHz)

Even higher information rate transmissions over power line use RF through microwave frequencies transmitted via a transverse mode surface wave propagation mechanism that requires only a single conductor. An implementation of this technology is marketed as E-Line. These use microwaves instead of the lower frequency bands, up to 2–20 GHz. While these may interfere with radio astronomy when used outdoors, the advantages of speeds competitive with fibre optic cables without new wiring are likely to outweigh that.

These systems claim symmetric and full duplex communication in excess of 1 Gbit/s in each direction. Multiple Wi-Fi channels with simultaneous analog television in the 2.4 and 5.3 GHz unlicensed bands have been demonstrated operating over a single medium voltage line conductor. Because the underlying propagation mode is extremely broadband (in the technical sense), it can operate anywhere in the 20 MHz – 20 GHz region. Also since it is not restricted to below 80 MHz, as is the case for high-frequency BPL, these systems can avoid the interference issues associated with use of shared spectrum with other licensed or unlicensed services.

Real Plug and Play Last Mile Communications System

The worldwide patented UHF based power line communication products’ advantages are that: there is no need for any installation to deploy several hundred Mbit/s to several Gbit/s throughput speed with AC-WAN(TM) to AC-LAN(TM) modems for the Last Mile communication application; there are no interference problems; it is the cheapest Last Mile solution; the most stable Last Mile solution among wireless and BPL products; it communicates without repeater for +500 meter distance in any rural area directly through any size transformers, between the three-phase power lines and through the electricity meters; it communicates with repeater for the last couple of mile distances directly through any size transformers, between the three-phase power lines and through the electricity meters; it delivers around 100 Mbit/s throughput speed for the Last Mile application.

Typical wireless and BPL products throughput speed is about 10–20% of the raw data rate. What this means is that the advertised 200 Mbit/s modem will deliver maybe 1–10 Mbit/s throughput speed beyond 300 meters after several repeaters. These types of modems throughput speed is also significantly changing when the power load or the number of users are changing.

The AC-WAN(TM) to AC-LAN(TM) modems’ throughput speed is about 50% of the raw data rate and resolve these problems since the power load changes or the number of user changes don’t affect its throughput speed significantly.


Power-over-fiber, or PoF, is a technology in which a fiber optic cable carries optical power, which is used as an energy source rather than, or as well as, carrying data. This allows a device to be remotely powered, while providing electrical isolation between the device and the power supply. Such systems can be used to protect the power supply from dangerous voltages such as from lightning, or to prevent voltage from the supply from igniting explosives.

Fiber Media Converter

From Wikipedia, the free encyclopedia


A Fast Ethernet fiber converter (100BASE-FX(ST) to 100BASE-TX)

A fiber media converter is a simple networking device that makes it possible to connect two dissimilar media types such as twisted pair with fiber optic cabling. They were introduced to the industry in the 1990s, and are important in interconnecting fiber optic cabling-based systems with existing copper-based, structured cabling systems. They are also used in metropolitan area network (MAN) access and data transport services to enterprise customers.

1 Media Conversion Types
2 Converter Types
3 Gigabit Interface Converter

Media Conversion Types

Fiber media converters support many different data communication protocols including Ethernet, Fast Ethernet, Gigabit Ethernet, T1/E1/J1, DS3/E3, as well as multiple cabling types such as coax, twisted pair, multi-mode and single-mode fiber optics. Media converter types range from small standalone devices and PC card converters to high port-density chassis systems that offer many advanced features for network management.

On some devices, Simple Network Management Protocol (SNMP) enables proactive management of link status, monitoring chassis environmental statistics and sending traps to network managers in the event of a fiber break or even link loss on the copper port.

Fiber media converters can connect different local area network (LAN) media, modifying duplex and speed settings. Switching media converters can connect different speed network segments. For example, existing half-duplex hubs can be connected to 100BASE-TX Fast Ethernet network segments over 100BASE-FX fiber.

When expanding the reach of the LAN to span multiple locations, media converters are useful in connecting multiple LANs to form one large campus area network that spans over a limited geographic area. As premises networks are primarily copper-based, media converters can extend the reach of the LAN over single-mode fiber up to 160 kilometers with 1550 nm optics.

Wavelength-division multiplexing (WDM) technology in the LAN is especially beneficial in situations where fiber is in limited supply or expensive to provision. As well as conventional dual strand fiber converters, with separate receive and transmit ports, there are also single strand fiber converters, which can extend full-duplex data transmission up to 120 kilometers over one optical fiber.

Other benefits of media conversion include providing a gradual migration path from copper to fiber. Fiber connections can greatly extend the reach and reduce electromagnetic interference.

Also fiber media converters pose as an alternative solution for switches not supporting fiber; ordinary switches can use fiber media converters to connect to a fiber network.

Converter Types


Opened case of a switching Fast Ethernet media converter (100BASE-TX to 100BASE-FX(SC))

Simple converters – when the speed and duplex settings on both media is identical – consist of two pairs of transmitters/receivers, each with their medium-dependent interfaces (when no data recoding is necessary) or their media-independent interfaces joined together back-to-back in a dual-simplex fashion. They can transport either half-duplex or full-duplex traffic but both sides must match.

Switching converters contain a network bridge and can connect two half-duplex segments without joining their collision domains.

Managed converters are usually of the switching kind and can additionally be managed by a network connection or a local console. However, most often pluggable transceivers are used instead when appropriate equipment already exists.

Gigabit Interface Converter

A GigaBit Interface Converter (GBIC) is a standard for transceivers, commonly used with Gigabit Ethernet and fibre channel in the 2000s.[citation needed] By offering a standard, hot swappable electrical interface, one gigabit port can support a wide range of physical media, from copper to long-wave single-mode optical fiber, at lengths of hundreds of kilometers.

A variation of the GBIC called the small form-factor pluggable transceiver (SFP), also known as mini-GBIC, has the same functionality but in a smaller form factor. Announced in 2001, it largely made the GBIC obsolete.




Optical Fiber Connector

From Wikipedia, the free encyclopedi


LC (top) and ST (bottom) optical fiber connectors, both with protective caps in place.

An optical fiber connector terminates the end of an optical fiber, and enables quicker connection and disconnection than splicing. The connectors mechanically couple and align the cores of fibers so light can pass. Better connectors lose very little light due to reflection or misalignment of the fibers. In all, about 100 fiber optic connectors have been introduced to the market.

1 Application
2 Types
2.1 Obsolete connectors
2.2 Notes
2.3 Mnemonics
2.4 Field-mountable connectors
3 Analysis
4 Testing
5 Notes
6 See also
7 References
8 External links


Optical fiber connectors are used to join optical fibers where a connect/disconnect capability is required. Due to the polishing and tuning procedures that may be incorporated into optical connector manufacturing, connectors are generally assembled onto optical fiber in a supplier’s manufacturing facility. However, the assembly and polishing operations involved can be performed in the field, for example, to make cross-connect jumpers to size.

Optical fiber connectors are used in telephone company central offices, at installations on customer premises, and in outside plant applications to connect equipment and cables, or to cross-connect cables.

Most optical fiber connectors are spring-loaded, so the fiber faces are pressed together when the connectors are mated. The resulting glass-to-glass or plastic-to-plastic contact eliminates signal losses that would be caused by an air gap between the joined fibers.

Every fiber connection has two values:

  • Attenuation or insertion loss
  • Reflection or return loss.

Measurements of these parameters are now defined in IEC standard 61753-1. The standard gives five grades for insertion loss from A (best) to D (worst), and M for multimode. The other parameter is return loss, with grades from 1 (best) to 5 (worst).

A variety of optical fiber connectors are available, but SC and LC connectors are the most common types of connectors on the market. Typical connectors are rated for 500–1,000 mating cycles. The main differences among types of connectors are dimensions and methods of mechanical coupling. Generally, organizations will standardize on one kind of connector, depending on what equipment they commonly use. Different connectors are required for multimode, and for single-mode fibers.

In many data center applications, small (e.g., LC) and multi-fiber (e.g., MTP/MPO) connectors are replacing larger, older styles (e.g., SC), allowing more fiber ports per unit of rack space and higher data rate application such as 40-Gigabit Ethernet and 100-Gigabit Ethernet.

Features of good connector design:

  • Low insertion loss
  • High return loss (low amounts of reflection at the interface)
  • Ease of installation
  • Low cost
  • Reliability
  • Low environmental sensitivity
  • Ease of use

Outside plant applications may require connectors be located underground, or on outdoor walls or utility poles. In such settings, protective enclosures are often used, and fall into two broad categories: hermetic (sealed) and free-breathing. Hermetic cases prevent entry of moisture and air but, lacking ventilation, can become hot if exposed to sunlight or other sources of heat. Free-breathing enclosures, on the other hand, allow ventilation, but can also admit moisture, insects and airborne contaminants. Selection of the correct housing depends on the cable and connector type, the location, and environmental factors. Careful assembly is required to ensure good protection against the elements.

Depending on user requirements, housings for outside plant applications may be tested by the manufacturer under various environmental simulations, which could include physical shock and vibration, water spray, water immersion, dust, etc. to ensure the integrity of optical fiber connections and housing seals.


Many types of optical connector have been developed at different times, and for different purposes. Many of them are summarized in the tables below.

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Obsolete Connectors

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  1. Modern connectors typically use a “physical contact” polish on the fiber and ferrule end. This is a slightly convex surface with the apex of the curve accurately centered on the fiber, so that when the connectors are mated the fiber cores come into direct contact with one another. Some manufacturers have several grades of polish quality, for example a regular FC connector may be designated “FC/PC” (for physical contact), while “FC/SPC” and “FC/UPC” may denote “super” and “ultra” polish qualities, respectively. Higher grades of polish give less insertion loss and lower back reflection.
  2. Many connectors are available with the fiber end face polished at an angle to prevent light that reflects from the interface from traveling back up the fiber. Because of the angle, the reflected light does not stay in the fiber core but instead leaks out into the cladding. Angle-polished connectors should only be mated to other angle-polished connectors. The APC angle is normally 8 degrees, however, SC/APC also exists as 9 degrees in some countries. Mating to a non-angle polished connector causes very high insertion loss. Generally angle-polished connectors have higher insertion loss than good quality straight physical contact ones. “Ultra” quality connectors may achieve comparable back reflection to an angled connector when connected, but an angled connection maintains low back reflection even when the output end of the fiber is disconnected.
  3. Angle-polished connections are distinguished visibly by the use of a green strain relief boot, or a green connector body. The parts are typically identified by adding “/APC” (angled physical contact) to the name. For example, an angled FC connector may be designated FC/APC, or merely FCA. Non-angled versions may be denoted FC/PC or with specialized designations such as FC/UPC or FCU to denote an “ultra” quality polish on the fiber end face. Two different versions of FC/APC exist: FC/APC-N (NTT) and FC/APC-R (Reduced). An FC/APC-N connector key will not fit into a FC/APC-R adapter key slot.
  4. SMA 906 features a “step” in the ferrule, while SMA 905 uses a straight ferrule. SMA 905 is also available as a keyed connector, used e.g., for special spectrometer applications.


  • LC connectors are sometimes called “Little Connectors”.
  • MT-RJ connectors look like a miniature RJ-45 connector.
  • ST connectors refer to having a “straight tip”, as the sides of the ceramic (which has a lower temperature coefficient of expansion than metal) tip are parallel—as opposed to the predecessor bi-conic connector which aligned as two nesting ice cream cones would. Other mnemonics include “Set and Twist”, “Stab and Twist”, and “Single Twist”, referring to how it is inserted (the cable is pushed into the receiver, and the outer barrel is twisted to lock it into place). Also they are known as “Square Top” due to the flat end face.
  • SC connectors, being square, have a mnemonic of “Square Connector”, which some people believe to be the correct name, rather than the more official “Subscriber Connector”. Other terms often used for SC connectors are “Set and Click” or “Stab and Click”.

Field-mountable Connectors

Field-mountable optical fiber connectors are used to join optical fiber jumper cables that contain one singlemode fiber. These assemblies can be separated into two major categories: single-jointed connector assemblies and multiple-jointed connector assemblies. According to Telcordia GR-1081, a single-jointed connector assembly is a connector assembly where there is only one spot where two different fibers are joined together. This is the situation generally found when connector assemblies are made from factory-assembled optical fiber connector plugs. A multiple-jointed connector assembly is a connector assembly where there is more than one closely spaced connection joining different fibers together. An example of a multiple-jointed connector assembly is a connector assembly that uses the stub-fiber type of connector plug.

Field-mountable optical fiber connectors are used for field restoration work and to eliminate the need to stock jumper cords of various sizes.


  • FC connectors’ floating ferrule provides good mechanical isolation. FC connectors need to be mated more carefully than the push-pull types due to the need to align the key, and due to the risk of scratching the fiber end face while inserting the ferrule into the jack. FC connectors should not be used in vibrating environments due to its threaded lock. FC connectors have been replaced in many applications by SC and LC connectors.
  • There are two incompatible standards for key widths on FC/APC and polarization-maintaining FC/PC connectors: 2 mm (“Reduced” or “type R”) and 2.14 mm (“NTT” or “type N”). Connectors and receptacles with different key widths either cannot be mated, or will not preserve the angle alignment between the fibers, which is especially important for polarization-maintaining fiber. Some manufacturers mark reduced keys with a single scribe mark on the key, and mark NTT connectors with a double scribe mark.
  • SC connectors offer excellent packing density, and their push-pull design reduces the chance of fiber end face contact damage during connection; frequently found on the previous generation of corporate networking gear, using GBICs.
  • LC connectors have replaced SC connectors in corporate networking environments due to their smaller size; they are often found on small form-factor pluggable transceivers.
  • ST connectors have a key which prevents rotation of the ceramic ferrule, and a bayonet lock similar to a BNC shell. The single index tab must be properly aligned with a slot on the mating receptacle before insertion; then the bayonet interlock can be engaged, by pushing and twisting, locking at the end of travel which maintains spring-loaded engagement force on the core optical junction.
  • In general the insertion loss should not exceed 0.75 dB and the return loss should be higher than 20 dB. Typical insertion repeatability, the difference in insertion loss between one plugging and another, is 0.2 dB.
  • On all connectors, cleaning the ceramic ferrule before each connection helps prevent scratches and extends the connector life substantially.
  • Connectors on polarization-maintaining fiber are sometimes marked with a blue strain relief boot or connector body, although this is far from a universal standard. Sometimes a blue buffer tube is used on the fiber instead.
  • MT-RJ (Mechanical Transfer Registered Jack) uses a form factor and latch similar to the 8P8C (RJ45) connectors. Two separate fibers are included in one unified connector. It is easier to terminate and install than ST or SC connectors. The smaller size allows twice the port density on a face plate than ST or SC connectors do. The MT-RJ connector was designed by AMP, but was later standardized as FOCIS 12 (Fiber Optic Connector Intermateability Standards) in EIA/TIA-604-12. There are two variations: pinned and no-pin. The pinned variety, which has two small stainless steel guide pins on the face of the connector, is used in patch panels to mate with the no-pin connectors on MT-RJ patch cords.
  • MPO (Multi-fiber Push On) is a connector for ribbon cables with four to twenty-four fibers. Connectors for singlemode fiber have angled ends to minimize back-reflection, while multimode fiber versions typically have flat ends. MTP is a brand name for a version of the MPO connector with improved specifications. MTP and MPO connectors intermate.
  • Hardened Fiber Optic Connectors (HFOCs) and Hardened Fiber Optic Adapters (HFOAs) are passive telecommunications components used in an Outside Plant (OSP) environment. They provide drop connections to customers from fiber distribution networks. These components may be provided in pedestal closures, aerial and buried closures and terminals, or equipment located at customer premises such as a Fiber Distribution Hub (FDH) or an Optical Network Terminal or Termination (ONT) unit.

These connectors, which are field-mateable and hardened for use in the OSP, are needed to support Fiber to the Premises (FTTP) deployment and service offerings. HFOCs are designed to withstand climatic conditions existing throughout the U.S., including rain, flooding, snow, sleet, high winds, and ice and sand storms. Ambient temperatures ranging from –40°C (–40°F) to +70°C (158°F) can be encountered.

Telcordia GR-3120 contains the industry’s most recent generic requirements for HFOCs and HFOAs.


Glass fiber optic connector performance is affected both by the connector and by the glass fiber. Concentricity tolerances affect the fiber, fiber core, and connector body. The core optical index of refraction is also subject to variations. Stress in the polished fiber can cause excess return loss. The fiber can slide along its length in the connector. The shape of the connector tip may be incorrectly profiled during polishing. The connector manufacturer has little control over these factors, so in-service performance may well be below the manufacturer’s specification.

Testing fiber optic connector assemblies falls into two general categories: factory testing and field testing.

Factory testing is sometimes statistical, for example, a process check. A profiling system may be used to ensure the overall polished shape is correct, and a good quality optical microscope to check for blemishes. Optical Loss / Return Loss performance is checked using specific reference conditions, against a reference-standard single mode test lead, or using an “Encircled Flux Compliant” source for multi-mode testing. Testing and rejection (“yield”) may represent a significant part of the overall manufacturing cost.

Field testing is usually simpler. A special hand-held optical microscope is used to check for dirt or blemishes. A power meter and light source or an optical loss test set (OLTS) is used to test end-to-end loss, and an optical time-domain reflectometer may be used to identify significant point losses or return losses.


Jump up ^ Pedestal terminal closures are intended to house passive telecommunications components used in an Outside Plant (OSP) environment. According to Telcordia GR-13, these closures may house such components as copper terminal blocks, coaxial taps, or passive fiber optic distribution equipment used for the distribution of telephone service and broadband services.

66 Block

From Wikipedia, the free encyclopedia

66_block (1)

A split-50 M or 66 Block with bridging clips

A 66 block is a type of punchdown block used to connect sets of wires in a telephone system. They have been manufactured in three sizes, A, B, and M. A and B have six clips in each row while M has only 4. The A blocks spaced the rows farther apart, and has been obsolete for many years. The B style is used mainly in distribution panels where several destinations (often 1A2 key telephones) need to connect to the same source. The M blocks are often used to connect a single instrument to such a distribution block. 66 blocks are designed to terminate 22 through 26 AWG solid copper wire. The 66 series connecting block, introduced in the Bell System in 1962, was the first terminating device with insulation displacement connector technology. The term 66 block reflects its Western Electric model number.

The 25-pair standard non-split 66 Block contains 50 rows; each row has four (M) or six (B) 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 (M) or six (B) clips, but the left two (or three) clips are electrically isolated from the right two (or three) clips. Smaller versions also exist with fewer rows for residential use.

66 blocks are available pre-assembled with an RJ-21 female connector that accepts a quick connection to a 25-pair cable with a male end. These connections are typically made between the block and the customer premises equipment (CPE).

1 Use



66 Block B series with 6 clips in each row. Jumper wires on the left connect the top pair with the bottom pair, allowing to split up to 10 devices.

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 premises equipment 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 point by the local exchange carrier.

Modern 110 blocks largely supplanted 66 blocks for new commercial installations at the end of the 20th century, as the capability for a circuit to carry digital data overlaid its ability to carry analog voice conversations. 110 block termination is almost always Category 5 (or higher) compliant, and capable of supporting 100 MHz (or faster) signaling. Compared to 110 and higher-density wire terminating blocks, 66 blocks are physically large; and because of their maximum 16 MHz Category 3 signaling compatibility, they are ill-suited for high speed (faster than 10BASE-T) data circuits. However, special Category 5e Certified 66 blocks are 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 frames to interconnect circuits with bridging clips, but are primarily limited to narrowband circuits such as POTS/DSL, DS0, or DS1 circuits.

25-pair Color Code

The 25-pair color code, originally known as even-count color code, is a color code used to identify individual conductors in twisted-pair wiring for telecommunications.

Color Coding

With the development of new generations of telecommunication cables with polyethylene-insulated wire by Bell Laboratories for the Bell System in the 1950, new methods were developed to mark each individual conductor in cables. Each wire was identified by the combination of two colors, one of which is the major color, and the second the minor color. Major and minor colors are chosen from two different groups, resulting in 25 color combinations. The color combinations are applied to the insulation that covers each conductor. Typically, the major color was a solid, background color on the insulation. The minor color was a tracer, consisting of stripes, rings, or dots, applied over the background. The minor color always matches the major color of its paired conductor.

The major, or primary group of colors consists of the sequence of white, red, black, yellow, and violet. The minor, or secondary color was chosen from the sequence blue, orange, green, brown, and slate.

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The wire pairs are referred to either directly by their color combination, or by the pair number. For example, pair 9 is also called the red-brown pair. In technical tabulations, the colors are often suitably abbreviated.

Violet is the standard name in the telecommunications and electronics industry, but it is sometimes referred to as purple. Similarly, slate is a particular shade of gray. The names of most of the colors were taken from the conventional colors of the rainbow or optical spectrum, and in the electronic color code, which uses the same ten colors (though in a different order).

When used for POTS, the first wire is known as the tip or A-leg (U.K.) conductor and is usually connected to the positive side of a direct current (DC) circuit, while the second wire is known as the ring lead or B-leg (U.K.), and is connected to the negative side of the circuit. Neither of these two sides of the line has a connection to the local ground. This creates a balanced audio circuit with common-mode rejection, also known as a differential pair. The tip and ring convention is based on the  1⁄4″ (6.5 mm) TRS phone connectors, which were employed in telephone switchboards in the 19th and 20th centuries, where the tip contact of the connector is separated from the ring contact by a spacer of insulation. The connection furthest from the cable is known as the tip, the middle connection is the ring, and the (largest) connection closest to the wire is the sleeve.

25-pair Telco Cable Pinout

A common application of the 25-pair color code is the cabling for the Registered Jack interface RJ21, which uses a female 50-pin miniature ribbon connector, as shown in the following table. The geometry of the pins of the receptacle (right hand image) corresponds to the pin numbers of the table. The left column of pins are the ring (R) conductors, while all tip (T) conductors are on the right.

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110 Block

From Wikipedia, the free encyclopedia


A 110 punch block.

A 110 block is a type of punch block used to terminate runs of on-premises wiring in a structured cabling 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 older 66 block.

1 Usage
1.1 Telephone distribution
1.2 Computer networks
2 Advantages
3 Problems


Telephone distribution

Early residential telephone systems used simple screw terminals to join cables to sockets in a tree topology. 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 on-premises wiring to outlet boxes throughout the home in star topology. At the outlet box, cables are punched down IDC type connectors, which fit in special faceplates.

In commercial settings, this style of home run or star topology 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 IDC connection is often used at both ends of Category 5 cable runs through buildings, as shown in the image. In switch rooms, 110 blocks are often built into the back of patch panels to terminate cable runs. At the other end, 110 connections may be used with keystone modules that are attached to wall plates. 110 blocks are preferred over 66 blocks in high-speed networks because they introduce less crosstalk and many are certified for use in Category 5, Category 6 and Category 6a wiring systems.

Individual cat5e 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.


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


During regular usage, 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 on 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 intermittent jumper wire.

Patch Panel

From Wikipedia, the free encyclopedia


A remote broadcast trailer’s jackfield


A couple of managed Gigabit Ethernet rackmount switches, connected to the Ethernet ports on a few Panduit patch panels using Category 6 patch cables (all equipment is installed in a standard 19-inch rack)

A patch panel, patch bay, patch field or jack field 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 panels are commonly used in computer networking, recording studios, radio and television.

1 Uses and connectors
2 Normalization
3 Switches
4 See also
5 References

Uses and Connectors

In recording studios, television and radio broadcast studios, and concert sound reinforcement systems, patchbays are widely used to facilitate the connection of different devices, such as microphones, electric or electronic instruments, effects (e.g. compression, reverb, etc.), recording gear, amplifiers, or broadcasting equipment. Patchbays make it easier to connect different devices in different orders for different projects, because all of the changes can be made at the patchbay. Additionally, patchbays make it easier to troubleshoot problems such as ground loops; even small home studios and amateur project studios often use patchbays, because it groups all of the input jacks into one location. This means that devices mounted in racks or keyboard instruments can be connected without having to hunt around behind the rack or instrument with a flashlight for the right jack. Using a patchbay also saves wear and tear on the input jacks of studio gear and instruments, because all of the connections are made with the patchbay.

Patch panels are being used more prevalently in domestic installations, owing to the popularity of “Structured Wiring” installs. They are also found in home cinema installations more and more.



A patch bay for patching circuits to stage lighting instruments


Rear view of a patch panel with dual coax patch jacks.

It is conventional to have the top row of jacks wired at the rear to outputs and bottom row of jacks wired to inputs. Patch bays may be half-normal (usually bottom) or full-normal, “normal” indicating that the top and bottom jacks are connected internally. When a patch bay has bottom half-normal wiring, then with no patch cord inserted into either jack, the top jack is internally linked to the bottom jack via break contacts on the bottom jack; inserting a patch cord into the top jack will take a feed off that jack while retaining the internal link between the two jacks; inserting a patch cord into the bottom jack will break the internal link and replace the signal feed from the top jack with the signal carried on the patch cord. With top half-normal wiring, the same happens but vice versa. If a patch bay is wired to full-normal, then it includes break contacts in both rows of jacks.


Dedicated switching equipment can be an alternative to patch bays in some applications. Switches can make routing as easy as pushing a button, and can provide other benefits over patch bays, including routing a signal to any number of destinations simultaneously. However, switching equipment that can emulate the capabilities of a given patch bay is much more expensive.

For example, an S-Video matrix routing switcher with the same capability (8×8) as a 16-point S-Video patch panel (8 patch cables connects 8 inputs and 8 outputs) may cost ten times more, though it would probably have more capabilities, including audio-follow-video and built-in distribution amplifiers.

There are various types of switches for audio and video, from simple selector switches to sophisticated production switchers. However, emulating or exceeding the capabilities of audio and/or video patch bays requires specialized devices like routing switches and crossbar switches.

Like patch panels, switching equipment for nearly any type of signal is available, including analog and digital video and audio, as well as RF (cable TV), MIDI, telephone, networking, electrical, and just about anything else.

Switching equipment may be electronic, mechanical, or electro-mechanical. Some switcher hardware can be controlled via computer and/or other external devices. Some have automated and/or pre-programmed operational capabilities. There are also software switcher applications used to route signals and control data within a “pure digital” computer environment.

Distribution frames are cheaper, but less convenient.