eemmcqsem3

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Short answer type question

Q1. What is the maximum number of point of light, fan and socket- outlets that can be connected in one

sub-circuit

!ns. "en.

Q#. What is the maximum load $light and fan% that can be connected in one sub-circuit

!ns. &'' Watts.

Q(. )n what basis is the number of circuits* sub-circuits determined in house wiring installations

!ns. "he number of circuits and sub-circuits is decided on the basis of total number of point to be wired

and the total load to be connected to the supply system.

Q+. Which system is used for distribution of electrical energy in a building

!ns. istribution board system.

Q. Which system is used in connections of arious lamps or appliances in parallel

!ns. /oop-in 0system.

Q. Which of the following wiring system is commonly used for light*fan load in domestic and commercial

buildings$a% 2leat wiring

$b% 2asing-capping wiring

$c% "3S wiring

$d% /ead sheathed wiring$e% 452 wiring

!ns. $e% 452 wiring

Q6. Which wiring system is employed in mechanical workshops

!ns. 2onduit wiring system $surface or concealed%.

Q&. What are that points which will be consider in selecting the wiring for a particular installation

!ns. "he main points, which are considered in selection of the type of wiring for a particular installation,

are safety, durability, appearance mechanical protection, permanency, accessibility and cost $initial as well

as maintenance%.

Q7. What is different between wire and cable

!ns. Single wire, may be bare or coered with insulation is called the wire while seeral wires strandedtogether is called the cable.

Q1'. Why conductor is coered with insulating material

!ns. "he conductor is coered with insulating material so as to preent leakage of current from theconductor.



Q11. What are the essential properties, which the insulation used in cable must posses

!ns. "he insulating materials used in cables must hae the properties of light resistiity, high flexibility,

high dielectric strength, non-inflammability, non-hygroscopicity, highly resistie to moisture, acids or

alkalies and capability to withstand high rupturing oltage and high temperature without much

deterioration.

Q1#. Which insulation is most widely used for coering wires*cables used in internal wiring

!ns. 452.

Q1(. Why multi-stand conductors are preferred oer solid conductors

!ns. 8ulti-strand conductors are preferred oer solid conductors because they proide flexibility and

durability.

Q1+. 452 cables are most widely used in internal wiring. Why

!ns. 452 cables are most widely used in internal wiring because 452 insulation proides better flexibility,

has better insulation qualities, has no chemical effect on metal of wire and gies smaller diameter of cable.

Q1. Where are flexible cords used

!ns. 9lexible cords are used as connecting wires for such purposes as from ceiling rose to lamp holder,

socket outlet to portable apparatus such as radios, fans, lamps etc.

Q1. What is meant by oltage grading of cables

!ns. 5oltage grading of cable specifies the safe oltages which the insulation of the cable can withstand.

Q16. :ow the si;e of a wire or cable is gien

!ns. "he si;e of a wire or cable is specified giing the number of strands used and diameter of each strand

or giing the area of cross-section of conductor used.

Q1&. :ow are cable specified

!ns. "he cables are specified proiding si;e of conductor used, type of conductor used, number of coresthat cable consists of, oltages grade and type of cable.

Q17. What is meant by distribution board

!ns. istribution board is an assembly of parts, including one or more fuses or circuit breakers, arranged

for the distribution of electrical energy to different circuits or other distribution boards known as submain

distribution boards.

Q#'. What is meant by a switch

!ns. ! switch is a deice that is used for making or breaking the electric circuit in a conenient way.



Q#1. What for ceiling rose is used

!ns. 2eiling rose is used for connecting the pendant lamps, fans or fluorescent tubes to the installation

through flexible plastic or silk coered wire.

Q##. What is meant by a fuse

!ns. 9use is a deices used in an electrical circuit for protecting electrical equipment against oerloadsand*or shor-circuits.

Q#(. )n what principle does the fuse operate

!ns. "he action of a fuse is based upon the heating effect of the electric current. uring oerloads or short

circuits the fuse gets heated upto melting point due to excessie current and breaks the circuit.

Q#+. What kind of protection is offered by a fuse

!ns. "he fuse proides protection against short-circuits and oerloads.

Q#. What function does the fuse perform

!ns. "he function of a fuse wire is $i% to carry the normal working current safely without heating and $ii% to break the circuit when current exceeds the limiting current.

Q#. <ie the names of fie materials with their melting points which are used for fuse element.

!ns. "he materials commonly used for fuse elements are siler, tin, lead, copper and

aluminium. "heir melting points are 7&'= 2, #+'= 2, (#&= 2, 1,'7'= 2, and = 2, respectiely.

Q#6. What material is mostly used for an ordinary fuse wire

!ns. 2opper or lead-tin alloy.

Q#&. What is fuse link

!ns. 9use link is that part of the fuse which needs replacement when the fuse blows out.

Q#7. )n what factors does the current carrying capacity of a fuse depend

!ns. "he current carrying capacity of a fuse depends upon the permissible temperature rise of the contacts

of the fuse holder, si;e of fuse wire, fuse material and the surrounding of the fuse.

Q('.)n What factors does the fusing current depends

!ns. "he fusing current depends upon $i% diameter of wire $ii% length of wire $iii% fuse material $i% x-

section area $round or rectangular% $% si;e location of terminals $i% types of enclosure used $ii% type ofsurface etc.

Q(1. What are the purposes of using quart; sand as filler materials in the construction of :32 fuse

!ns. "he purposes of using quart; sand as filler material in the construction of :32 fuse are to absorb heat

at a ery high rate, to produce a substance of high resistance and aoid the oxidation of siler element.

Q(#. 2an the :32 fuse be used for both ac and dc circuits. >f so under what condition



!ns. >n general an :32 fuse meant for ac circuit may not be used for dc circuits? but howeer, a fuse

satisfying the requirement of arc oltage can be used on both ac and dc circuits.

Q((. What is meant by earth continuity conductor

!ns. "he conductor, by means of which the metal body of an equipment or an application is connected to

the earth, is known as earth continuity conductor $@22%.

Q(+. What are maximum permissible alues of resistance of earth system for $a% /arge power stations $b%

maAor power station $c% small substations $d% in all other cases

!ns. 8aximum permissible alue of resistance of earth system are as followingB

/arge power stations -'.C

8aAor power station -1.' C

Small power station -#.' C>n all other cases - C maximum

Q(. What should be the minimum si;e of earth continuity conductor!ns. "he cross-section of earth continuity conductor should not be either less than #.7 mmD $1+ SW<% or

half of the installation conductor si;e.

Q(. What is harm if earth resistance exceeds the permissible alue of earth resistance

!ns. "he sensitiity of the protectie equipment, system oltage and the maximum fault current directlyrelate to permissible alue, then in the eent of earth of earth resistance. >n case the earth resistance exceeds

the permissible alue, than in the eent of earth fault, the fault current may not reach a sufficient alue to

operate the protectie equipment $such as fuses or relays% and dangerous condition may arise.

Q(6. What is an earth electrode!ns. !ny wire, pipe, rod or metal plate embedded in earth for the purpose of making an effectie electrical

connection with the general mass of earth is known as earth electrode.

Q(&. What is an earthing lead!ns. "he wire which connects oerhead earth wire or any other apparatus to be earthed to the earth

electrode is known as earthing lead.

Q(7. Why charcoal and salt is used in earthing.!ns. <enerally alternate layers of charcoal and salt are used to increase the effectie area of the earth and to

reduce the earth resistance respectiely.

Q+'. What is the aerage resistance of a human body!ns. !bout 1,''' C.

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