Series connection within each room and parallel connection elsewhere
Answer.2. Parallel connection
Domestic electric wiring is basically done in parallel connection so that if one appliance stops working due to Some defect, all other appliances keep working normally. In the parallel circuit if R1, R2, and R3 are the resistances of different household electrical appliances and I current enters the circuit then the current passing through three resistances will be I1, I2 and I3 so that total current I = I1 +I2 +I3. Every appliance can draw the required amount of current. So, if one of the appliances gets fused or damaged, other circuits will work.
But in option (a) if suppose resistances of different appliances are connected in series, the same current will flow through all appliances. Thus if one of the appliances does not work circuit appliances could not draw current and will cause inconvenience. Hence series connection can not be used in domestic electrical wiring.
Option (c) and (d) i.e combination of series and parallel connections are also not suitable because current I will be distributed into I1, and I2 along with I (across R) which is in series. As explained above, if the first appliance would stop work or gets damaged, then the entire circuit would break and no current will further flow.
2. What are the types of cables used in domestic wiring?
Vulcanized Indian Rubber
Tough Rubber Sheathed
Polyvinyl Chloride insulated cables
All of the above
Answer.4. All of the above
A cable is made up of conducting material, (copper or aluminum) surrounded by insulation and a sheath giving it mechanical protection. Insulation is provided on the conducting material to block the path of leakage current from the conductor, thus minimizing the risk of shock and fire. Normally cables are classified according to the insulation used over the conductor. The various classifications of cable commonly used for domestic wiring are as follows.
(i) Vulcanized Indian Rubber insulated cables (VIR).
(ii) Tough Rubber Sheathed cables (TRS)
(iii) Cab Tyre Sheathed cables (CTS)
(iv) Weather-proof cables
(v) Polyvinyl Chloride insulated cables (PVC)
(vi) Lead sheathed cables.
3. Which of the following is the type of wiring system?
All of the above
Answer.4. All of the above
The main types of wirings usually employed in residential buildings, commercial buildings, and industries are as follows:
Casing and capping wiring
CTS or TRS wiring
4. The type of wiring that is highly suitable for a temporary shed is
Wooden capping and casing wiring
Lead sheathed wiring
Answer.1. Cleat wiring
In this type of wiring, insulated conductors (usually VIR, Vulcanised Indian Rubber) are supported on porcelain or wooden cleats. The cleats have two halves: one base and the other cap. The cables are placed in the grooves provided in the base and then the cap is placed. Both are fixed securely on the walls by 40 mm long screws. The cleats are easy to erect and are fixed 4.5-15 cms apart. This wiring is suitable for temporary installations where cost is the main criteria but not the appearance.
Advantages of cleat wiring:
It is a simple and cheap wiring system
Most suitable for temporary use i.e. under construction building or army camping
As the cables and wires of the cleat wiring system are in the open environment, Therefore fault in cables can be seen and repair easily.
5. The type of conductor used in the Cleat wiring system is
PVC and VIR
Any of the above
Answer.3. PVC and VIR
Material Used in cleat wiring: The various materials used in cleat wiring are VIR or PVC insulated wires, weatherproof cables, porcelain or plastic cleats (two or three grooves), and screws.
6. The cheapest system of wiring is
Casing and capping
Answer.2. Cleat wiring
Cleat wiring is one of the cheapest wiring systems considering the initial cost and labor and it is most suitable for a temporary electrical wiring system.
7. Which of the following is are the advantages of the Cleat wiring system?
Easy to locate the fault
No effect of weather condition
Used for permanent wiring
Answer.1. Easy to locate the fault
Advantages of Cleat Wiring:
It is a simple and cheap Wiring system.
Most suitable for temporary use i.e. under construction building or army camping.
As the cables and wires are in the open air. Therefore fault in cables can be seen and repair easily.
Cleat wiring system installation is easy and simple.
Inspection, alteration, and additions can be made easily
A little skill is required to lay the wiring.
This wiring can be installed very quickly.
The wiring can be dismantled and recovered very quickly.
8. For cleat wiring and 250 volts supply, the cables will be placed_____ apart center to center for single-core cables
This type of wiring is not used practical for permanent wiring and is only suitable for temporary wiring purposes such as for marriages with advantages of saving labor and overall cost.
The cleat should be provided every 60 cm to avoid sag in the cables. Sharp bends should be avoided in the wiring and the spacing between the cleats should be reduced to prevent the touching of the wall and sagging. The distance between the cables should be 2.5 cm in the case of branch circuits and 4 cm apart in the case of sub-mains.
9. Which of the following are disadvantages of the cleat wiring method?
Can’t be used for domestic wiring
All of the above
Answer.4. All of the above
Disadvantages of Cleat wiring:
Appearance is not so good.
Cleat wiring can’t be used for permanent use because Sag may occur.
In this wiring system, the cables and wiring are in the open air, therefore, oil, Steam, humidity, smoke, rain, chemical, and acidic effect may damage the cables and wires.
It can be only used on 250/440 Volts at low temperatures.
There is always a risk of fire and electric shock.
Note:- The other disadvantage of this wiring system is that its life is short as there is no continuous base for the wires. It is not used for domestic wiring. Instead, it is used in industries and workgroups for temporary wirings.
10. Which among these is a type of internal wiring?
I. Cleat wiring
II. Conduit wiring
III. CTS wiring
Both II & III
I, II & III
Answer.4. I, II & III
Electrical wiring is done in residential and commercial buildings to provide power for lights, fasts, pumps, and other domestic appliances are known as domestic wiring. There are several wiring systems in practice such as tree systems and distribution systems.
Types Of wiring
The following are the different types of wiring systems used for domestic electrical installation.
Cleat wiring system
The wooden casing-capping wiring system
PVC wiring or CTS or TRS wiring system
Lead sheathed wiring system
Conduit wiring system.
This system of wiring is the cheapest one. This system is used for insulated cables like rubber insulated cable, PVC cable etc. The cables are run over cleats made of porcelain. The cleats are generally in pairs having the bottom and top halves. The bottom half is grooved to receive the wire and the top is for cable grip.
This wiring is suitable for temporary installations where cost is the main criterion. Since this type of wiring installation is affected by weather conditions therefore it is mainly used as internal wiring.
PVC wiring or CTS or TRS wiring system:
This system is very widely used. In such wiring, the wires used are sheathed with the tough rubber of P.V.C. wires and they are clipped on the wooden button with clips. The button is ﬁxed on the wall or ceiling.
This wiring is suitable for damp climates, but cannot withstand much heat and so is not suitable for places of very hot weather and there is also the danger of mechanical damage and ﬁre hazard. C.T.S. wires are not suitable for outdoor use. Therefore, they should not be exposed to direct sunlight and where there are corrosive acid fumes.
Conduit wiring system
In conduit wiring, wires are carried through steel or iron pipes giving good protection from mechanical injury or ﬁre risks. The conduits are buried inside the walls on wooden gutties and the wires are drawn through them with fish (steel) wires. This system is the best and most desirable system of wiring for workshops and public buildings.
Nowadays P.V.C. conduit pipes are also available which do not require threading. Jointing is done with a special mode solution. These are ﬂexible and can be bent easily. For concealed wiring, the pipes are directly buried in the wall and roofs, and then wires are drawn through them.