What is Cable or Wire Splicing?

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What is Cable or Wire Splicing?

 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 the process of splicing a wire, 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 wires 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, as it is a complex electrical work.
  • 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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