Exam question on different types of wiring systems

The following types of wiring are used in the electrical wiring system.
1)Cleat wiring.
2)Wooden casing and capping wiring.
3)CTS or TRS or PVC sheath wiring.
4)Lead sheathed or metal sheathed wiring.
5)Conduit wiring.
6)Concealed wiring
From the above question ,metal conduit wiring and concealed are explained as follows
1) Concealed Wiring :
The cost of wiring is very high. The PVC or VIR wires are carried through the channels made in ceilings and walls at the time of building construction. This wiring is slightly difficult but appearance is very good, so it is widely used. More number of wires can be carried through the different size of channels. Wires are not exposed to the sky, so there are less chances of mechanical injury. Fault finding is difficult. Future expansion is not possible and repairing and maintenance difficult.
2)Metal conduit wiring
The cost of wiring is high. The PVC or VIR wires are carried through metal conduit. This wiring is very simple. More number of wires can be carried through the different size of metal conduit. Wires are not exposed to the sky, so there are less chances of mechanical injury. future expansion is not easily possible. Generally metal conduit wiring is preferred in industries or workshops but if there is any earth fault then the leakage current may pass through the conduit and hence now a days it is rarely used.

Electric wiring is done for passage of electricity in a house or office or factory. Earlier the electric wires were laid on the outside of a wall by clamping them on a wooden rod. Later the conduit wiring design came in practice in which a metal or plastic pipe was placed either outside the wall or inside the wall plaster and through this pipe the electric wires were taken from one place to another.

(i) Concealed wiring - In this design the plastic or metallic pipe is hidden in the plaster of the wall and is not seen from outside. Only switch boards are visible on the wall. The wiring is taken through these pipes in the house or office and thus all the wiring is in concealed state and nothing is visible form outside. Nowadays this is the preferred mode of wiring.

(ii) Metal conduit wiring - In this design the metal conduit is fixed on the wall with clamps at places and then the wire goes through it. This mode is generally used in temporary sheds or construction places where it is to be removed after the work.

Concealed Conduit wiring is done inside the wall slots with the help of plastering. The electrical wiring done with the help of metallic or plastic piping is known as concealed conduit wiring. In the conduit wiring, the steel tubes which is known as conduit are placed on the surface walls by the help of pipe hooks or either placed in walls using plaster. The PVC cables are placed using GI wire with a size of 18SWG.
In the conduit wiring system, the conduits must be placed electrically in a continuous manner and must be connected to earth at suitable points. This is a good way of wiring a building. In the domestic wiring, PVC conduits are used. Conduit wiring protects the cable from getting damaged, when rodents come in contact it can cause a short circuit and that is the reason the circuit breakers are placed in between. Conduits are of two types.
1. Metallic Conduit
2. Non-Metallic Conduit

1. Metallic Conduit:
Metallic Conduit is strong and it is made of steel and it is really costly in nature. Metallic conduits are of two types.

a. Class A:
Here thin layer steel sheet conduit is used and it is low gauge conduit.

b. Class B:
It is a thick sheet of steel conduit and it is having a high gauge conduit.

2. Non-Metallic Conduit:
Here a solid PVC conduit is used as a non-metallic conduit. It is easy to bend and it is also flexible. The common conduit pipes are of different sizes like 13, 16.2 etc.

Concealed wiring is a kind of concealed conduit wiring system. It is a rather a cumbersome process of installation since layout of wiring is carried out under the plaster of the wall with the provision of GI wire inside the structure.
After the application of of GI wires, the main PVC is insulated cables are drawn through the conduit.
Advantages of this system -
1) No risk of electrical shock.
2) It offers a long life.
3) There is no risk to damage of the cable installation.
4) Installation will not take part in the process of combustion.
5) It is a reliable wiring system.
6) Renovation can be taken up for the replacement of old wires.
7) It is ideal for the areas where humidity, smoke and chemical effects exist.
8) It will offer a long lasting service.
Disadvantages-
1) Complication may appear in case of managing additional connections in future.
2) PVC conductors are not suitable below minus 5 degree centigrade or above 60 degree centigrade.
3) Wiring installation is difficult as compared to other methods.
4) This is an expensive system.
Metal conduit wiring -
Electrical conduits are the durable tubing consisting of an enclosure used to protect wiring conductors.
A conduit may be made up of either a metal or a plastic with the sufficient rigidity or flexibility in its structure. Rigid metal conduit is a heavy duty galvanised steel tube installed with the threaded fittings. It is sold in different in different lengths with the provision of threads on both the ends.
There is also a different variety known as Flexible Metal Conduit having a special construction so that it can pass through the walls and other structures. It is used in dry indoor locations.