Introduction to Casing Capping Wiring System

Casing Capping Wiring System: Advantages, Disadvantages and Uses


Casing Capping Wiring- Installation means the act of installing something. Connecting two things or recombining two things in such a specific configuration or sequence that a complete system builds as a result of their joining or conjugation, is called installation. Electrical installation means the provision of corresponding supply to electrical appliances or instruments and their induction together with the safety circuits. The electrical installation provides a safe source for connecting electrical appliances of a consumer with electrical supply through over current and earth leakage protection. It consists of all cables, pertinent safety components, and control gear. In short, fixing different types of circuits and electrical equipment on a panel, recombination of electrical components with an incomplete system for making a complete system thereof, installation of electrical wiring in a precise or correct fashion either temporarily or permanently, installation of protective gadgets, installation of service lines on a one floor or multi-floor buildings, installation of motors, installation of load and earthing system are all included in electrical installation. In fact, the electrical installation consists of a complete system of all types of electrical wiring and its associated electrical components or instruments, protection, testing, signal communication circuits, and entire instruments related to the electrical control, installed in residential and commercial buildings, industrial units, factories, and refineries, etc.  

Wiring Systems

The following wiring systems or methods are used:

  1. Cleat Wiring System
  2. Batten Wiring System
  3. Casing Capping Wiring System
  4. Conduit Wiring System

Conduit wiring may further be classified into the following two types

(i). Surface Conduit Wiring

(ii). Concealed Conduit wiring

Casing Capping Wiring System

This type of wiring system once used to be very popular. However, now it has been replaced by the conduit wiring system. Although this wiring system is quite ancient, however, it is still being used in offices, homes, shops, and other ordinary premises.

There are the following two types of casing capping wiring systems.

(i). Wooden Casing Capping Wiring

(ii). PVC Casing Capping Wiring

 Wooden Casing Capping Wiring

In this type of wiring system, a rectangular casing made from dried teak wood or cedar timber, wherein two or three “U” shaped grooves on the length side are formed, is used. This rectangular type wide clamp, wherein grooves are being molded, is called casing. The casing is installed on the wall with the help of dowel pins or rowel plugs. Wires are being inserted into the casing grooves (usually, neutral and phase wires are inserted into grooves separately). In order to cover and control these wires inserted into the grooves, another thin rectangular type strip is fixed above the casing through screws, which is called capping. As the width of capping above the casing is the same, therefore wires are completely covered as a result of installing capping over the casing. Remember that capping is also wooden and it is used for covering purposes. Therefore, it is absolved of grooves and thinner as compared to the casing. In figure 1.5, casing–capping has been illustrated.

Casing Capping Wiring

Capping is tightened above the casing through screws, whereas the casing is installed on dowel pins or rowel plugs fitted on walls through screws. Lines are marked on the casing for identification of different wires, owing to which screws proposed to be used on the casing, do not damage any cable existing on the casing, and only grasp or control the middle part of the casing. In a fine casing capping wiring, a 3mm (1/8 inches) rounded porcelain cleat is fitted between wall and casing in order to keep the casing away from the wall, so that wall moisture does not cause any sort of damage to the casing wood. Initially, tweak wood was used for the casing – capping, however, due to being extremely expensive, now cedar timber is used for this purpose.

Casing and capping are available in different sizes. The width of a commonly used size is 38 mm (1.5 inches) and the thickness 16 mm (5/8 inches). The width of grooves in it is equivalent to 6 mm (1/4 inches). One piece of casing – capping is about 3 meters or 10 feet in length, which can be cut and used as desired. Screws are fixed on the casing at a distance of about 1 meter whereas screws on capping are fitted at a distance of approx. 30 cm. if the casing size is large, in such a situation distance of screws to be used on walls is reduced from 1 meter to 60 cm. Apart from 38 mm, the casing is also available in 44, 51, 64-, 76-, 89- and 102-mm width sizes. This type of wiring is pretty suitable for 250 / 440 volts. Mostly, VRI and PVC cables are used in the casing–capping wiring. Such type of wiring can be carried out both vertically as well as horizontally. Neutral and phase wires can be inserted into casing grooves combined together however, for easy identification and as a precaution, phase and neutral wires are not combined together in one casing groove. Sometimes, a sleek varnish is done prior to the installation of Casing and capping.  


(1). This type of wiring is relatively economical as compared to conduit and sheathed wiring system

(2). This type of wiring system is durable and enduring

(3). As wires remain invisible, low-quality wires can also be used

(4). As wires remain hidden and as a result of neat and clean installation, it presents a decent look

(5). An addition or alteration can easily be done in this type of wiring system as and when required

(6). If phase and neutral wires are inserted separately within the grooves, fault can easily be tracked and repaired quite quickly and easily

(7). As a result of capping, such type of wiring remains protected against moisture, sunlight, smoke, dirt, and dust.

(8). Its installation is pretty easy

(9). Wires in the casing – capping are completely covered, as such, they remain protected against electric shock

(10). The services of an expert technician are not normally required for this type of wiring

(11). As this type of wiring is done on a wooden strip, therefore it is more insulated

(12). It has a long operational life


(1). It is prone to catching fire or inflammable

(2). Its repair is costly and also involves wastage of excessive material

(3). This method involves a lot of labor. It is also difficult to re-apply accessories that have already been used in the casing-capping wiring.

(4). This type of wiring is not suitable for places having moisture or in open areas, because its casing is damaged through water and moisture etc.

(5). Its material is not commonly available nowadays

(6). If phase and neutral wires are not inserted separately into the grooves carefully, it becomes difficult to track down and remove the fault.

(7). White ants attack and damage casing and capping beyond repair.

(8). This type of wiring system is suitable only for low voltage installation.

(9). This type of wiring is possible only on the surfaces of walls and it is not possible inside the walls.

(10). This wiring cannot be used in places having acids and alkalizing.


This type of wiring is suitable for dry places and places that have minimum chances of fire incidence and low voltage household installation. Therefore, this wiring system is generally used in residential premises, offices, railway stations, schools, hospitals, shops, etc.

PVC Casing Capping Wiring

As the name implies, PVC is used in this type of wiring instead of timber. Nowadays this method of wiring is rapidly gaining popularity as compared to the wooden casing capping wiring method. Because most of the problems observed in the casing capping wiring method have been removed. In this method of wiring, a rectangular PVC-made strip or casing is installed on the wall with the help of dowel pins or rowel plugs through screws. Subsequently, wires are inserted into this casing and covered with PVC casing. As no grooves are found in the PVC casing contrary to the wooden casing, therefore a relatively large number of wires can be accommodated into it. As PVC capping does not require screws to be fitted on the casing, therefore this type of capping can easily be removed or fitted again as and when required. The width of both casing and capping remains equal. The sizes being generally used are 25 mm, 38 mm, and 51 mm. The length of one piece of casing – capping normally tends to be 3 meters (10 feet) and its operational or working age is about 20 years. In figure 1.6, PVC casing–capping has been illustrated.

Figure 1.6 – PVC casing capping wiring

Casing Capping Wiring


This type of wiring is mostly used in offices, shops, residential houses, schools, laboratories, computer labs, etc.


(1). It is relatively strongly built and reliable

(2). As wires are completely covered, therefore no risk of an electric shock exists in this type of wiring system

(3). It has a very long life

(4). It looks very decent and pretty

(5). It is less costly as compared to the wooden casing – capping wiring

(6). This type of installation is quite easy. Moreover, no expert technicians are required for this type of installation

(7). It is not affected by moisture or water. Moreover, it also has no danger of worm-eating by white ants

(8). Addition or alterations can easily be done in this type of wiring. Moreover, its repairing is less costly

(9). It can also be installed in places having acids and alkalize

(10). As compared to the same size wooden casing–capping, a large number of wires can be injected into it

Next Topic: Conduit Wiring System

Previous Topic: Batten Wiring System

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Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

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