問題一覧
1
A polarised capacitor should never be used
in an AC circuit
2
The conductors contained in busvar trunking are usually
bare copper or aluminum bars
3
The B type MCB will operate magnetically at
3-5 times it rated current
4
IS/EN 60309 plugs and sockets outlets rated for 400 are what color
red
5
Voltage drop in cables can be reduced by
increasing the CSA of the conductors
6
Eddy currents losses in a power transformer is minimized by
constructing the core with laminated layers
7
Multiple surface runs of armoured cables are normally installed
on cable tray
8
What is the formula for calculating capacitance of two capacitors connected in parallel?
Ct= c1+c2
9
Where the lengths of steel trunking are joined, they must be
bonded tiger with copper straps
10
Which of the following is the abbreviation used to indicate the current rating of a circuit fuse or MCB ?
In
11
A remote stop button connected to a direct on line started should be
connected in series with the local stop button
12
The surface finish of a cable tray used in damp situations must be
hot dipped galvanized
13
The color of the first phase of a three phase and neutral fixed wiring system must be
brown
14
A current flowing towards the viewer in a cross- section of a conductor is shown in a diagram by
a dot
15
Minimum IP rating for industrial sockets on agricultural and horticultural environments is
IP 44
16
Two coils are placed side by side one induces an EMF into the other the result is called
dynamic induction
17
A tungsten halogen lamp that is operated at slightly more than its rated voltage will have a
shorter life and brighter light
18
Which of the following characteristics applies to AC but not to DC
frequency
19
From lenz law, when the current in a coil increases the self induced voltage will
produce a current in opposition to the increasing current
20
If discrimination between fuses is correct in an electrical installation then
the fuse nearest a fault will rupture first
21
Any circuit that induces EMF into itself is said to be
self inductive
22
The main reason for limiting the number of cables which may be run through a conduit is
that cables may be easily drawn in and removed
23
A permanent magnet may lose its magnetism if it is
heated or hammered
24
An AC supply has a frequency of 200Hz. This means that
the waveform completes 200 cycles every second
25
A capacitor consists of two
conducting materials separated by an insulator
26
Conduit boxes are galvanised to
prevent corrosion
27
If the north seeking poles of two magnets are brought close together they will
repel each other
28
The main advantage of installing steel conduit over pvc conduit is that
it provides superior mechanical protection to pvc
29
Voltage drop in cables can be reduced by ?
increasing the cross sectional area of the conductors
30
When using a clip on ammeter to check the motor current, it is necessary to have the motor
connected to the supply and running
31
Which of the following statements is correct
exceeding the rated voltage of a capacitor will damage it
32
If an iron core is inserted in a solenoid and the current is maintained at a constant value the magnetic flux will
increase in strength
33
The minimum level of IP protection on all fittings where water hosing is used in a farm location is ?
IP 55
34
An example of a device that works on the principle of electromagnetism is a
relay
35
Another name for an auxiliary winding in a single phase motor is
the start winding
36
The tables of current ratings and voltage drop in cables in the ETCI rules are based on an ambient temperature of
30°
37
The highest value reached by an alternating voltage in a half cycle is called
maximum of peak value
38
Metallic cable tray is
an exposed conductive part and must be earthed
39
A running coupler is used on steel conduit
when neither conduit can be rotated
40
Which is the standard frequency used in this country
50hz
41
Which of the following statements is true
the transformer works on the principle of mutual induction
42
The effect that limits the flow of current in an AC circuit containing a capacitor is called
capacitance reactance
43
The phase voltage in this country is
230 v
44
If the primary voltage of a transformer is greater than its secondary voltage it is called a ?
step down transformer
45
Plastic conduit must be used only within the manufacturers prescribed ranges of
ambient temperature
46
Extra low voltage cables may be run in a steel trunking system along with the low voltage cables
all cables are insulated for the highest voltage present
47
The Henry is the unit of
inductance
48
Good earth continuity on a steel conduit installation requires
low resistance
49
PVC conduit is suitable for use within the temperature ranges of
-5 and 65 degrees
50
The construction of a capacitor is accurately described as
having two conducting plates separated by an insulator
51
Full on and off control of the lighting in a corridor from three positions requires which of the following combination of switches
two 2 way and one intermediate types
52
Formula for the calculation of the volt drop in cable is
millivolt per amp per meter
53
In a three phase, four wire system the neutral conductor is needed to ?
provide for single phase supplies
54
The type of rotor used in a three phase induction motor is ?
a squirrel cage rotor
55
The cable gland used in terminating a SWA cable
clamps the armouring wires securely
56
In large commercial installations discharge lighting circuits are divided over three phases to overcome the
stroboscopic effect
57
In a permanent magnet, the lines of flux external to the magnet are said to start
at the magnetic North Pole
58
All motors convert to
electrical energy to mechanical energy
59
If a soft iron core is inserted into a solenoid the magnetic field will
become more concentrated
60
When using flemings right hand or left hand rule the second finger points in the direction of
current flow
61
Standard supply of voltage in Ireland
400-230
62
Once a single phase capacitor start motor is running at its rated speed the centrifugal switch
disconnects the start winding from the supply
63
The material between the plates of a capacitor is known as
the dielectric
64
Extra low voltage cables may be run through a steel trunking system along with low voltage cables provided that
they are run in seperate compartments within the trunking
65
The fluorescent fitting has a capacitor connected between live and neutral at the beginning of the fitting circuit that helps to
improve the power factor of the unit
66
The primary function of metallic cable tray is to
provide support and fixing for sheathed cables
67
IS/EN 60309 socket outlets greater than 16 amps shall be supplied by?
seperate circuit
68
A large office having a three phase four wire supply derives its 230v supplies from
any one phase and neutral
69
Convert micro farad to farads
0.00025
70
The hearing effect of 25 amps AC when measured with a multimeter compared 25 amps DC is
the same