What do you call the method of joining two or more conductive wires together?

Table of Contents Show

General Considerations Regarding Cable Splicing
How To Splice A Wire?
Types of Fiber Optic Splicing
Fusion Splicing
Mechanical Splicing
Explanation
Unshielded twisted pair
Cable shielding
Analog telephone
Building infrastructure
Twisted ribbon cable
Solid-core vs. stranded cable
External links

When managing the electrical project, you will often find a need to splice electrical cables instead of buying new ones. Cable or wire splicing is the process of connecting the endpoints of two or more cable conductors. During cable splicing, the wires of different length are joined together while their original characteristics remain the same. Splicing can be performed on electrical and fiber optical cables.

The primary purpose of splicing is to allow spliced wires to carry the current. By performing splicing, you have the opportunity to connect damaged cables instead of installing new ones. Splicing cables can be a cheaper alternative to investing in new ones. However, splicing requires knowledge and some practice, so it is not an option for those without basic electrical knowledge.

You can also expand an electrical cable to reach a desired electrical circuit. For instance, coaxial cables in the house are often joined together when they do not reach the cable source or TV set in the house, so a single wire is formed. Cables are also spliced to extend fixture boxers or when heading a branch circuit in several separate directions. Slicing also comes in handy when moving lighting fixtures or breaking walls in the house.

General Considerations Regarding Cable Splicing

It is not recommended to splice different wire gauges together because of the potential concerns about ampacity that would result in the current overloading.
Cables that are joined together should have the same AWG size, as well as an identical number of conductors.
As a rule, cable splicing does not lead to changes in voltage.
For safety considerations, always turn the power off in the circuit when performing cable splicing.
You can safely splice three or more wires as long as you follow basic instructions. Pigtail is the best type of splicing when connecting three or more wires because it prevents one of the splices from remaining straight while others are twisted around it. When this occurs, the splicing might fail because the straight wire can be easily pulled out of the construction.
Do not use tape alone to splice wires without twist-on wire caps. This procedure is not approved by UL, and the wires are at risk of losing their original characteristics, such as flame retardancy, moisture resistance, etc.
Do not leave splices to hang alone inside the walls or ceilings as it is not safe. Instead, keep the splices in a jbox.
When in doubt, rely on a professional to perform cable splicing.
There is a variety of popular electrical splices and joints used in cable splicing, including pig tails, y-splices, knotted tabs, aerial tabs, cross joints, and duplex cross joints. While pig tail is the most common type of splicing, you should educate yourself about these types to find which one is suitable for you. For instance, y-splices are performed on small cables with flexible strands.
For basic cable splicing, you will need the following tools: an electrical cable ripper, a wire stripper, a hammer, a screwdriver, working gloves, pliers, a cordless drill, and an extender for it. You will also need to gather materials to perform splicing, including a jbox, cable clamps for it, wire connectors as recommended by the UL, woodscrews, and a grounding pigtail.
You would need a separate set of tools for fiber optic splicing, including fiber strippers, crimp tools, tubing cutters, kevlar scissors, needle-nose pliers, fiber scribes, tweezers, and a jacket stripper.

How To Splice A Wire?

After you made sure that all safety concerns are met, it is time to splice your wires. While there are several methods of splicing, we will review two of the simplest and most common. The first one is stripping wires prior to splicing, while the second one is splicing with the help of a twist-on wire cap that is often called "a wire nut." Follow these basic steps to perform splicing. As a rule, all manipulations should be performed within a junction box.

If you choose to strip the wires before splicing:

Remove one inch of every wire's insulation. If the cable has splicing, first remove it with the help of a cable ripper.
Clamp the wire into a hole of a wire stripper that is one or two sizes smaller than your wire and remove the insulation altogether.
Place a 3-inch shrink tube into one of the wires before slicing to make it easier to put the wire in place after.

If you choose to apply a twist-on wire cap:

Press the endpoints of the wires together so that they touch each other tightly.
Clip the twist-on wire cap into the wires in a clock-wise direction.
Pull the wires to see if they stay in place. If they fall out, press the twist-on wire cap tighter.
Connect the wire caps and the wires with electrical tape. A rubber EPR tape is perfectly suitable for this purpose.
Cut the tape when the splicing is completed with the help of a utility knife.

Types of Fiber Optic Splicing

The splicing of fiber optic cables differ from regular cable splicing. While regular electrical cables' splicing is always mechanical, fiber optic cables can be joined using two methods: mechanical splicing and fusion splicing.

Fusion Splicing

During fusion splicing, a special kind of fusion splicer machine is used to connect the two fibers. The ends are attached using electrical heat by creating an electrical arc. Thanks to the use of the machine, the connection between the two fibers is transparent and non reflective. Do mind that fusion splicing is more pricey than the mechanical one; however, it is considered higher quality and gives a longer life to the spliced cables. With fusion splicing, there is less reduction of the electrical current and less transmission loss. Fusion splicing is typically performed by a skilled technician. The typical loss of light transmission during the fusion splicing is around 0.1 dB, and the insertion loss is even less than this.

Mechanical Splicing

Mechanical splicing is the technique that allows joining fiber optic cables manually using only tools without a special electrical device. The fibers are connected using a special index matching liquid. The mechanical splice that connects the fibers is usually about 6 cm long. A covering is used to speed up the splicing process.

Mechanical splicing is a cheaper and faster method of connecting fibers. However, the reflection is higher than when using the fusion method. The insertion loss in the case of mechanical splicing is usually less than 0.5dB, while the splicing loss is around 0.3dB.

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Type of wiring used for communications

25-pair color code chart

Twisted pair cabling is a type of wiring used for communications in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a single conductor or an untwisted balanced pair, a twisted pair reduces electromagnetic radiation from the pair and crosstalk between neighboring pairs and improves rejection of external electromagnetic interference. It was invented by Alexander Graham Bell.[1]

For additional noise immunity, twisted-pair cabling may be shielded. Cable with shielding is known as shielded twisted pair (STP) and without as unshielded twisted pair (UTP).

Explanation

A twisted pair can be used as a balanced line, which as part of a balanced circuit can greatly reduce the effect of noise currents induced on the line by coupling of electric or magnetic fields. The idea is that the currents induced in each of the two wires are very nearly equal. The twisting ensures that the two wires are on average the same distance from the interfering source and are affected equally. The noise thus produces a common-mode signal which can be cancelled at the receiver by detecting the difference signal only, the latter being the wanted signal.

Common-mode rejection starts to fail on untwisted wires when the noise source is close to the signal wires; the closer wire will couple with the noise more strongly and the receiver will be unable to eliminate it. This problem is especially apparent in telecommunication cables where pairs in the same cable lie next to each other for many miles. Twisting the pairs counters this effect as on each half twist the wire nearest to the noise-source is exchanged. Provided the interfering source remains uniform, or nearly so, over the distance of a single twist, the induced noise will remain common-mode.

The twist rate (also called pitch of the twist, usually defined in twists per metre) makes up part of the specification for a given type of cable. When nearby pairs have equal twist rates, the same conductors of the different pairs may repeatedly lie next to each other, partially undoing the benefits of twisting. For this reason it is commonly specified that, at least for cables containing small numbers of pairs, the twist rates must differ.[2]

In contrast to shielded or foiled twisted pair (typically S/FTP or F/UTP cable shielding), UTP cable is not surrounded by any shielding. UTP is the primary wire type for telephone usage and is very common for computer networking.

History

Wire transposition on top of pole

The earliest telephones used telegraph lines which were single-wire earth return circuits. In the 1880s electric trams were installed in many cities, which induced noise into these circuits. In some countries, the tram companies were held responsible for disruption to existing telegraph lines and had to pay for remedial work.[a] For new installations, however, it was necessary to protect against existing trams from the outset. Interference on telephone lines is even more disruptive than it is on telegraph lines. Telephone companies converted to balanced circuits, which had the incidental benefit of reducing attenuation, hence increasing range.

As electrical power distribution became more commonplace, this measure proved inadequate. Two wires, strung on either side of cross bars on utility poles, shared the route with electrical power lines. Within a few years, the growing use of electricity again brought an increase of interference, so engineers devised a method called wire transposition, to cancel out the interference.

In wire transposition, the wires exchange position once every several poles. In this way, the two wires would receive similar EMI from power lines. This represented an early implementation of twisting, with a twist rate of about four twists per kilometre, or six per mile. Such open-wire balanced lines with periodic transpositions still survive today in some rural areas.

Twisted-pair cabling was invented by Alexander Graham Bell in 1881.[4] By 1900, the entire American telephone network was either twisted pair or open wire with transposition to guard against interference. Today, most of the millions of kilometres of twisted pairs in the world are outdoor landlines, owned and maintained by telephone companies, used for voice service.

Unshielded twisted pair

Cross-section of cable with four unshielded twisted pairs

Unshielded twisted pair (UTP) cables are found in many Ethernet networks and telephone systems. For indoor telephone applications, UTP is often grouped into sets of 25 pairs according to a standard 25-pair color code originally developed by AT&T Corporation. A typical subset of these colors (white/blue, blue/white, white/orange, orange/white) shows up in most UTP cables. The cables are typically made with copper wires measured at 22 or 24 American Wire Gauge (AWG),[5] with the colored insulation typically made from an insulator such as polyethylene or FEP and the total package covered in a polyethylene jacket.

For urban outdoor telephone cables containing hundreds or thousands of pairs, the cable is divided into small but identical bundles. Each bundle consists of twisted pairs that have different twist rates, as pairs having the same twist rate within the cable can still experience some degree of crosstalk. The bundles are in turn twisted together to make up the cable.

Unshielded twisted pair cable with different twist rates

UTP is also the most common cable used in computer networking. Modern Ethernet, the most common data networking standard, can use UTP cables, with increasing data rates requiring higher specification variants of the UTP cable. Twisted-pair cabling is often used in data networks for short and medium-length connections because of its relatively lower costs compared to optical fiber and coaxial cable.

As UTP cable bandwidth has improved to match the baseband of television signals, UTP is now used in some video applications, primarily in security cameras.[6] As UTP is a balanced transmission line, a balun is needed to connect to unbalanced equipment, for example any using BNC connectors and designed for coaxial cable.

Cable shielding

F/UTP cable

S/FTP cable

U/FTP, F/UTP and F/FTP are used in Cat 6a cables

Twisted pair cables may incorporate shielding in an attempt to prevent electromagnetic interference. Shielding provides an electrically conductive barrier to attenuate electromagnetic waves external to the shield. The shield also provides a conduction path by which induced currents can be circulated and returned to the source via ground reference connection. Such shielding can be applied to individual pairs or to a collection of pairs. Shielding may be foil or braided wire.

When shielding is applied to a collection of pairs, it is usually referred to as screening, but usage among vendors and authors in applying such words as screening, shielding, and STP (shielded twisted pair) can be subject to variability.[7][8] ISO/IEC 11801:2002 (Annex E) attempts to internationally standardize the various designations for shielded cables by using combinations of three letters - U for unshielded, S for braided shielding (in outer layer only), and F for foil shielding - to explicitly indicate the type of screen for overall cable protection and for protecting individual pairs or quads, using a two-part abbreviation in the form of x/xTP.

Shielded Cat 5e, Cat 6/6A, and Cat 8/8.1 cables typically have F/UTP construction, while shielded Cat 7/7A and Cat 8.2 cables use S/FTP construction.[9]

Because the shielding is conductive, it may also serve as a path to ground. A foil-shielded, twisted pair cable may have an integrally incorporated grounding wire called a drain wire which makes electrical contact with the shield. The purpose of the drain wire is for easy connection to terminals which are usually designed for connection of round wires.

Common shield construction types include:

Individual shield (U/FTP) Individual shielding with aluminum foil for each twisted pair or quad. Common names: pair in metal foil (PiMF), shielded twisted pair, screened twisted pair. This type of shielding helps prevent EMI from entering or exiting individual pairs and also protects neighboring pairs from crosstalk. Overall shield (F/UTP, S/UTP, and SF/UTP) Overall foil, braided shield or braiding with foil across all of the pairs within the 100 ohm twisted pair cable. Common names: foiled twisted pair, shielded twisted pair, screened twisted pair. This type of shielding helps prevent EMI from entering or exiting the cable. Individual and overall shield (F/FTP, S/FTP, and SF/FTP) Individual shielding using foil between the twisted pair sets, and also an outer foil or braided shielding. Common names: fully shielded twisted pair, screened foiled twisted pair, shielded foiled twisted pair, screened shielded twisted pair, shielded screened twisted pair. This type of shielding helps prevent EMI from entering or exiting the cable and also protects neighboring pairs from crosstalk.

An early example of shielded twisted-pair was IBM STP-A, which is a two-pair 150 ohm S/FTP cable defined in 1985 by the IBM Cabling System specifications, and used with Token Ring or FDDI networks.[7][10]

Common industry nomenclature for cable construction types

Industry abbreviations	ISO/IEC 11801 designation[A]	Cable shielding	Pair shielding
UTP, TP	U/UTP	None	None
FTP, STP, ScTP	F/UTP	Foil	None
STP, ScTP	S/UTP	Braiding	None
SFTP, S-FTP, STP	SF/UTP	Braiding and Foil	None
STP, ScTP, PiMF	U/FTP	None	Foil
FFTP, STP	F/FTP	Foil	Foil
SSTP, SFTP, STP, STP PiMF	S/FTP	Braiding	Foil
SSTP, SFTP, STP	SF/FTP	Braiding and Foil	Foil

^ The code before the slash designates the shielding for the cable itself, while the code after the slash determines the shielding for the individual pairs: U – unshielded F – foil shielding S – screened shielding (outer layer only) TP – twisted pair TQ – twisted pair, individual shielding in quads

Types

Analog telephone

Before digital communication and Ethernet became widespread there was no international standard for telephone cable. Standards were set at a national level. For instance, in the UK the General Post Office specified CW1293 and CW1308 cables. CW1308 was a similar specification to the earlier CW1293 but with an improved color code. CW1293 used mostly solid colors on the cores making it difficult to identify the pair it was twisted with without stripping back a large amount of sheath. To solve this problem. CW1308 has narrow rings of the paired color printed over the base color. Both cables are a similar standard to category 3 cable.[11][12]

Prior to the common use of polyethylene and other plastics for insulation, telephone twisted pair cable was insulated with waxed paper or cotton with a wax coating applied to the copper. The overall sheath of this type of cable was usually lead. This style of cable came into use in the late 19th century shortly after the invention of the telephone.[13] The cable termination in termination boxes were sealed with molten wax or a resin to prevent the ingress of moisture which would seriously degrade the insulating properties of the paper insulation.[14] However, such seals made future maintenance and changes more difficult. These cables are no longer made but are still occasionally encountered in old buildings and in various external areas, commonly rural villages.

Building infrastructure

Standard types of twisted pair cabling

Name	Typical construction	Bandwidth	Applications	Notes
Level 1		400 kHz	Telephone and modem lines	Not described in EIA/TIA recommendations. Unsuitable for modern systems.[15]
Level 2		4 MHz	Older terminal systems, e.g. IBM 3270	Not described in EIA/TIA recommendations. Unsuitable for modern systems.[15]
Cat 3	UTP[16]	16 MHz[16]	10BASE-T, 100BASE-T4[16]	Described in EIA/TIA-568. Unsuitable for speeds above 16 Mbit/s. Now mainly for telephone cables.[16]
Cat 4	UTP[16]	20 MHz[16]	16 Mbit/s Token Ring[16]	Not commonly used[16]
Cat 5	UTP[16]	100 MHz[16]	100BASE-TX, 1000BASE-T[16]	Common for current LANs. Superseded by Cat 5e, but most Cat 5 cables meet Cat 5e standards.[16] Limited to 100 m between equipment.
Cat 5e	UTP,[16] F/UTP, U/FTP[17]	100 MHz[16]	1000BASE-T, 2.5GBASE-T[16]	Enhanced Cat 5. Common for current LANs. Same construction as Cat 5, but with better testing standards.[16] Limited to 100m between equipment.
Cat 6	UTP,[16] F/UTP, U/FTP[18]	250 MHz[16]	5GBASE-T, 10GBASE-T	ISO/IEC 11801 2nd Ed. (2002), ANSI/TIA 568-B.2-1. Most commonly installed cable in Finland according to the 2002 standard EN 50173-1. Limited to 55 m distance at 10GBASE-T
Cat 6A	UTP, F/UTP, U/FTP, S/FTP	500 MHz	5GBASE-T, 10GBASE-T	Improved standards, tested to 500 MHz. Full 100 m distance at 10GBASE-T ISO/IEC 11801 2nd Ed. Am. 2. (2008), ANSI/TIA-568-C.1 (2009)
Cat 7	S/FTP, F/FTP	600 MHz	?	ISO/IEC 11801 2nd Ed. (2002). Only with GG45 or TERA connectors. It is not recognized by the EIA/TIA.
Cat 7A	S/FTP, F/FTP	1 GHz	?	ISO/IEC 11801 2nd Ed. Am. 2. (2008). Only with GG45 or TERA connectors. It is not recognized by the EIA/TIA.
Cat 8.1	F/UTP, U/FTP	2 GHz	25GBASE-T, 40GBASE-T	ANSI/TIA-568-C.2-1, ISO/IEC 11801-1:2017
Cat 8.2	S/FTP, F/FTP	2 GHz	25GBASE-T, 40GBASE-T	ISO/IEC 11801-1:2017

Loaded

A loaded twisted pair has intentionally added inductance and was formerly common practice on telecommunication lines. The added inductors are known as load coils and reduce attenuation for voiceband frequencies but increase it on higher frequencies. Load coils reduce distortion in voiceband on very long lines.[19] In this context a line without load coils is referred to as an unloaded line.

Bonded

A bonded twisted pair is a construction variant in which the two wires of each pair are bonded together for the length of the cable. Pioneered by Belden, it is intended to help assure configuration consistency during and after installation. One key benefit is that the noise immunity performance of the cable can be protected despite potentially rough handling.[20] The enhanced performance may be unnecessary and bonding reduces the flexibility of the cable and makes it prone to failure where it is flexed.[21]

Twisted ribbon cable

Twisted ribbon cable used for SCSI connections

A twisted ribbon cable is a variant of standard ribbon cable in which adjacent pairs of conductors are bonded and twisted together. The twisted pairs are then lightly bonded to each other in a ribbon format. Periodically along the ribbon, there are short sections with no twisting where connectors may be attached using the usual ribbon cable IDC techniques.[22]

Solid-core vs. stranded cable

A punchdown block

A solid-core cable uses one solid wire per conductor and in a four-pair cable there would be a total of eight solid wires.[16] Stranded cable uses multiple wires wrapped around each other in each conductor and in a four-pair with seven strands per conductor cable, there would be a total of 56 wires (2 per pair × 4 pairs × 7 strands).[16]

Solid core cable is intended for permanently installed runs (permanent link). It is less flexible than stranded cable and is more prone to failure if repeatedly flexed due to work hardening. Stranded cable is used at patch panels and for connections from wall-ports to end devices (patch cord or drop cable), as it resists cracking of the conductors.

Connectors are designed differently for solid core than for stranded. Use of a connector with the wrong cable type can lead to unreliable cabling. Plugs designed for solid and stranded core are readily available, and some vendors even offer plugs designed for use with both types. The punch-down blocks on patch-panel and wall-port jacks are designed for use with solid core cable. These work via the insulation-displacement method, whereby the device pierces the sides of the insulation and "bites" into the copper conductor to form a connection. Punchdown blocks are used as patch panels or as breakout boxes, for twisted pair cable.

Properties

Twisted pair has the following useful attributes:[23]

Electrical noise going into or coming from the cable can be prevented.
Crosstalk is minimized.
Cheapest form of cable available for networking purposes.
Easy to handle and install.

Twisted pair has the following limitations:

Deformation: twisted pair's susceptibility to electromagnetic interference greatly depends on the pair twisting schemes staying intact during the installation. As a result, twisted pair cables usually have stringent requirements for maximum pulling tension as well as minimum bend radius. This fragility of twisted-pair cables makes the installation practices an important part of ensuring the cable's performance.[24]
Delay skew: due to different twist rates used to minimize crosstalk between the pairs, different pairs within the cable have different lengths and thus different delays. This can degrade image quality when multiple pairs are used to carry components of a video signal. Low skew cable is available to mitigate this problem.[25][26]
Imbalance: differences between the two wires in a pair can cause coupling between the common mode and the differential mode. Differential to common mode conversion produces common-mode currents that can cause external interference and can produce common-mode signals in other pairs. Common mode to differential mode conversion can produce differential mode signals from common-mode interference from other pairs or external sources. Imbalance can be caused by asymmetry between the two conductors of the pair from each other and in relationship to other wires and the shield. Some sources of asymmetry are differences in conductor diameter and insulation thickness.[b][27]

Notes

^ In Cape Town for instance, a balancing conductor was installed from the telegraph office through the streets and six miles out to sea to fix interference to the submarine telegraph cable from Luanda.[3]
^ In telephone jargon, the common mode is called longitudinal and the differential mode is called metallic.

References

^ McBee, David Barnett, David Groth, Jim (2004). Cabling : the complete guide to network wiring (3rd ed.). San Francisco: SYBEX. p. 11. ISBN 9780782143317.
^ "Crosstalk dependence on number of turns/inch for twisted pair versions of the end-cap umbilical cable" (PDF).
^ Trotter, A.P., "Disturbance of submarine cable working by electric tramways", Journal of the Institution of Electrical Engineers, vol. 26, iss. 130, pp. 501–514, July 1897.
^ US 244426, Bell, Alexander Graham, "Telephone-circuit", issued 1881 . See also TIFF format scans for USPTO 00244426
^ Steven T. Karris (2009). Networks: Design and Management. Orchard Publications. p. 6. ISBN 978-1-934404-15-7.
^ Christine Baeta (2008-10-27). "Troubleshooting UTP CCTV Systems".
^ a b Anitech Systems MP 4000 Manual
^ Grounding for Screened and Shielded Network Cabling - Siemon
^ Valerie, Maguire (2015-07-12). "Size of the Category 7A Installed Base" (PDF). Retrieved 2015-09-25.
^ "TechFest - IBM Cabling System Technical Summary". Archived from the original on 2014-03-11. Retrieved 2014-01-25.
^ Stephen Roberts (2001), Telephone Installation Handbook, Elsevier, pp. 32–34, ISBN 0080521487
^ Barry J. Elliot (2002), Designing a Structured Cabling System to ISO 11801, CRC Press, p. 269, ISBN 0824741307
^ Telephony, vol. 153, p. 118, Telephone Publishing Corporation 1957.
^ Paper Maker and British Paper Trade Journal, vol. 83-84, p. 294, November 1, 1932 OCLC 10634178
^ a b "CCNA: Network Media Types".
^ a b c d e f g h i j k l m n o p q r s t "Comparison between CAT5, CAT5e, CAT6, CAT7 Cables". Archived from the original on 2020-06-02. Retrieved 2022-07-18.
^ "Using UTP Cat5e vs. STP Cat5e Cable - SewellDirect.com". sewelldirect.com. Retrieved 2018-08-19.
^ "CAT3 vs. CAT5 vs. CAT6 - CustomCable". CustomCable. 2011-12-24. Retrieved 2018-08-19.
^ "Understanding Line Impairments". Cisco.com. Retrieved 2012-06-04.
^ "Contractor Field-Testing Survey Reveals Performance-Related Cost Savings Using Bonded-Pair Cables" (PDF). Belden.com. Belden. Retrieved 13 August 2016.
^ "Bonded Pair Cable" (PDF). Turck. Retrieved 2019-04-08.
^ "3M Twisted Pair Flat Cable" (PDF). 3M. Retrieved 13 August 2016.
^ "Twisted Pair Testing".
^ "The Impact of Installation Stresses On Cable Performance" (PDF). Belden. Retrieved 13 August 2016.
^ "7987R Technical Data Sheet (Metric)" (PDF). Belden.com. Belden. Retrieved 13 August 2016.
^ "7989R Technical Data Sheet (Metric)" (PDF). Belden.com. Belden. Retrieved 13 August 2016.
^ Reeve, Whitman D. (1995). Subscriber Loop Signaling and Transmission Handbook - Digital (1st ed.). IEEE Press. pp. 215–220. ISBN 0-7803-0440-3.