NEW
Font size
WorksheetsUNIT 18 PART 2
Total questions: 18
Worksheet time: 2hrs 30mins
Based on Table 41.3 of the SBC 401 given below, what is the maximum earth fault loop impedance in a system connected in a MCB, 32A, type C?
0.92 ohms
0.57 ohms
0.72 ohms
1.44 ohms
Referring to Table A.52-2 Installation Method A1, determine the proper size of the circuit breaker if the full-load ampere (FLA) is 32 A?
4 mm2
6 mm2
10 mm2
2.5 mm2
Based on Table A.52-14 of the SBC 401, what is the correction factor for PVC at 30°C?
0.94
1.06
1.00
1.12
If the resistance of supply line is 0.32ohms, and the resistance of protective earth conductor is also 0.32 ohms. Find the total earth fault loop impedance of the system (Zs), if the external impedance (Ze) is given as 0.15ohms.
0.79 ohms
0.47 ohms
0.32 ohms
0.64 ohms
Calculate the resistance of a 2.5mm square supply line, if the length is 30meters (30,000mm), resistivity of copper is 0.00001724 ohm-mm and the temperature factor is 1.30.
0.002718 ohms
0.2718 ohms
0.02718 ohms
2.718 ohms
Based on Table 41.3 of the SBC 401 given below, what is the maximum earth fault loop impedance in a system connected in a MCB, 16A, type B?
2.30 ohms
4.60 ohms
2.87 ohms
1.44 ohms
_______________ is the low impedance path to earth of fault current.
Fault current loop
Earth Fault loop impedance
Earthing Loop
Leakage current loop to earth
If the voltage drop across the conductor is 6.7%. Which of the following is true?
The conductor is good to be used
The conductor is not long enough
The conductor size (CSA) must be increased
The conductor size (CSA) must be decreased
In the Earthing System, PEN stands for ________________,
Planet Earth Nations
Proposed earth and neutral
Protective earth neutral
Protect the Earth’s Nature
If the size of the conductor is increased, the voltage drop of the conductor will
increase
decrease
be the same
not be known
Which of the following conductors will have the highest voltage drop?
25 meter 2.5 mm2 black conductor
10 meter 2.5 mm2 brown conductor
30 meter 2.5 mm2 gray conductor
20 meter 2.5 mm2 blue conductor
Decide which statement underneath best describes the direct contact from an electrical point of view:
A direct contact refers to the contact between two live lines
A direct contact refers to the contact between one live line to the earth
A direct contact refers to a person coming into contact with a conductor which is live in normal circumstances
A direct contact refers to a person coming into contact with an exposed-conductive-part which is not normally alive, but has become alive accidentally (due to insulation failure or some other cause).
If Ib<= In <= Iz
which of the following conditions is correct?
IN>IB
IZ<IB
IN<IB
IN>IZ
What is the minimum CSA of conductors that can be used for socket-outlet installations?
1.5 mm^2
2.5 mm^2
4.0 mm^2
6.0 mm^2
Which type of circuit breaker is suitable for purely resistive loads or loads with very small inductive component?
Hint: The minimum trip current is 3 to 5 times the rated current.
Type A
Type B
Type C
Type D
One of the bellow is an example of Earthing types :
TMT
MTANT
TN-C-S
S-C-TN
According to SBC401 the allowance for a voltage drop in consumer’s installations is:
40%
4% or more
4% or less
5%
Electrical resistivity has a unit of ____________________.
Ohms
Ohms * volts
Ohms/mm2
Ohms*mm
