Electrical wiring and power distribution Interview Question - Day 1

[Q:-01] What do you mean by electrical wiring ?

Ans :

      Electrical wiring means to run the wires or cables for distribution of electrical energy from the supply mains to connect different electrical appliances, machines etc. through their controlling and safety devices.

[Q:-02] What are the types of wiring ?

Ans :

(i) House wiring or Domestic wiring , and

(ii) Power wiring.

[Q:-03] What is house wiring ?

Ans :

      House wiring means a net-work of wires or cables connecting various accessories for distribution of electrical energy from the supplier's meter board to various electrical energy consuming devices in a house such as lamps, fans and other domestic appliances etc. through their controlling and safety devices.

[Q:-04] What do you mean by power wiring ?

Ans :

      Power wiring means a net-work of wires or cables connecting various high rating appliances for distribution of electrical energy from the supply mains to various power loads such as heaters, coolers, refrigerators, air-conditioners, motors, generators etc. through their controlling and safety devices.

[Q:-05] What are the systems of distribution wiring ?

Ans :

The two systems are as follows :—

(i) Tree system in which branch circuits are tapped from the main circuits at convenient places.

(ii) Distribution Board system in which the mains are taken to one or more distribution boards and the branch circuits are taken from the distribution boards.

[Q:-06] What are the points to be considered for wiring installation in a particular place ?

Ans :

(i) Durability,

(ii) Safety,

(iii) Cost,

(iv) Appearance , and

(v) Accessibility.

[Q:-07] What are the different systems of house wiring normally used in domestic installations ?

Ans :

      The following types of house wiring are used :—

(i) Cleat wiring,

(ii) Wooden casing and capping wiring,

(iii) C.T.S or T.R.S or P.V.C. batten wiring,

(iv) Metal sheathed wiring,

(v) Conduit wiring,

      (a) Surface or open type,

      (b) Recessed or Concealed type.

(vi) Mineral insulated wiring.

[Q:-08] What materials are generally used in cleat wiring ?

Ans :

      The materials are porcelain cleats (two way or three way), screws, wooden blocks, V.I.R or P.V.C wire, boards etc.

[Q:-09] What are the advantages of cleat wiring ?

Ans :

Advantages :-

(i) It is the cheapest type of wiring.

(ii) It can be easily and quickly installed.

(iii) Materials can be recovered when necessary

(iv) Easy inspection, additions and alterations are possible.

(v) Skilled labour is not required.

[Q:-10] What are the disadvantages of cleat wiring ?

Ans :

Disadvantages :-

(i) Its appearance is not good.

(ii) It's exposed to mechanical injury.

(iii) The insulation absorbs moisture and hence can not be used in damp places.

(iv) Oil and smoke affects V.I.R. insulation.

 [Q:-11] What should be the distance between two cleats ?

Ans :

Not greater than 60 cm (2 ft).

[Q:-12] Where is cleat wiring used ?

Ans :

      Cleat wiring is used for the cheap type of wiring and for temporary installation.

[Q:-13] What is casing and capping wiring ?

Ans :

      It is a system of wiring in which V.I.R or P.V.C or any other insulated cables are run through wood casing enclosure covered with the capping.

[Q:-14] What are the sizes of casings and cappings normally used ?

Ans : 3/2″ x 5/8″ , 7/4″ x 5/8″, 2″ x 3/4″,3″ x 1″ ,7/2″ x 5/4″, 4″ x 5/4″ etc.

[Q:-15] What are the advantages of casing wiring ?

Ans :

Advantages :—

(i) It shows neat appearance when properly installed.

(ii) It provides good insulation between conductors.

(iii) It is suitable for tropical climate where condensation is likely to occur in conduits.

(iv) It is easy to inspect by opening the capping.

[Q:-16] What are the disadvantages of casing wiring ?

Ans :

Disadvantages :

(i) It is costly.

(ii) It requires skilled labour and good workmanship.

(iii) It is not fire resistant.

(iv) It is affected by damp.

[Q:-17] Where is casing wiring used ?

Ans :

It is used for low voltage domestic installation.

[Q:-18] What are the restrictions of the use of casing wiring ?

Ans :

      Casing wiring should not be used in damp or ill-ventilated places, where the risk of fire and fume exists.

[Q:-19] What should be the distance between two fixing plugs ?

Ans :

      Not exceeding 90 cm (3 ft) for sizes upto 64 mm casing and not exceeding 60 cm (2 ft) for sizes above 64 mm casing.

[Q:-20] What should be the distance between two screws ?

Ans :

      Not exceeding 15 cm (6") crosswise (i.e. 30 cm between two successive screws on each side).

[Q:-21] How is the casing wiring to be done while crossing the wall ?

Ans :

Wiring should be done through a conduit pipe or P.V.C. pipe.

[Q:-22] Can the casing wiring be recessed or concealed ?

Ans :

No.

[Q:-23] Can you run two opposite polarity wires in one groove of casing ?

Ans :

      In no case of two cables of opposite polarity should be run in one groove.

[Q:-24] What are the names of joints used in casing wiring ?

Ans :

      Straight joint, Right angled joint, Corner joint, Tee joint, Bridge-Tee joint, Cross joint and Cross-Bridge joint.

[Q:-25] What types of joints are normally used in domestic wiring ?

Ans :

(i) Straight joint is used for increasing the length of the wiring.

(ii) Right angled joint is used where the wiring bends at 90°. &

(iii) Corner joint is used at wall corners.