Casing and Capping Wiring – Advantages and Disadvantages

The electrical wiring in which casing and capping are used is known as the casing and capping wiring system. Plastic casing and cap are used in this wiring system, hence called casing and capping wiring system. The case is a strip-like rectangular portion where the PVC insulated wires or the cables are placed. The case has grooves in it and the cables are run through them. The cap is used to cover the cables.

This is one of the simplest and oldest wiring systems. But it has not lost its popularity. The use of casing and capping wiring system is also seen in today’s world. Even after the introduction of some technically advanced wiring systems, casing and capping wiring system is also used frequently. It is a conventional form of the wiring system.

The cases and caps that are used cover the wires and the cables also provide a decorative look. This system is also known as cable trunking. The materials required for the installation of casing and capping wiring systems are less. The wires and the PVC insulated wires are used mainly. To insulate the wires a casing made up of plastic is used. The caps are used to insulate the casing wires. To provide the connections and turns between the wires elbow and joints are used. The use of the junction box is also required for this wiring system.

Casing and Capping types

Depending on the design of the system, it has four types.

1. Press and fit: it is a simple installation design. This type of wiring system has two layers and the wires are placed in between. The bottom layer is attached to the walls and the upper layer is attached to it.

2. Sliding and fit: to minimize the pressing labor in the press and fit system, the sliding fit design is used.

3. Trunked fit: in this design, the wires are put inside a hollow cylindrical trunk. This provides an additional protective layer to the system.

4. Grilled fit: this design provides a perfect use in telephone cables. Also, these are available in different sizes.

Casing and Capping joint types

The joints used in the system, it is divided into three types. They are

1. Elbow joint capping system: elbow joint is used for the placement of two perpendicularly aligned wiring cables.

2. T-shaped joint capping system: when there is a requirement of more than one connection of wires at a single point, this design is used.

3. Bridge joint capping system: a bridge joint is used for the connections of two wires in a different direction.

Casing and Capping wiring installation

The casing and capping wiring system installation is simple. The use of insulators is required for installation. To prevent the effects of humidity, insulators are put in between the casing and the wall. There are two designs for the installation: two-way design and three-way design. These two designs depending on the number of grooves created on the casing to run the wires. Using the joints, the wiring is done after grooving the wires in it.

In this system, the installation of wiring can be done in both horizontal and vertical ways. The use of this system is very easy. After installation, it gives a fine finishing and looks very decorative.

Casing and Capping wiring advantages

Some of the advantages of the casing and capping system are

  • The casing and capping wiring system is durable and long-lasting.
  • The cost of installation is cost-effective.
  • The installation is quite easy and quick.
  • Along with the PVC wires, the use of metallic wires is also possible.
  • The repairing of damage is easy and not costly.
  • The casing and capping protect against humidity and smoke.
  • The wiring system is strong and the risk of any electric shock is less.

Casing and Capping wiring disadvantages

The disadvantages of the casing and capping wiring system are as follows

  • The detection of a fault in this system is not easy.
  • This wiring system is not useful in industries as these are not suitable in acidic conditions.
  • In the case of short circuit condition and over heat, the plastic may be unable to hold the fire.
  • In the case of external use, the durability of the wiring system decreases.
  • Repairing needs more materials.
  • The wood casing and capping wiring system might get damaged by termites.
  • The presence of alkali is not suitable for this system.

Casing and Capping wiring applications

The applications of this wiring system are

  • For household wiring, the use of the casing and capping wiring system is done.
  • This wiring is used for the distribution of wires.
  • The casing and capping are used as protection to some other wiring system.
  • In offices and homes, this wiring system is used.
  • In the case of devices that use low voltage, a casing and capping wiring system is used.


Sunmoni Gohain
NIT Silchar



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