MBEYA UNIVERSITY OF SCIENCE AND TECHNOLOGY
DEPARTMENT: ELECTRICAL AND POWER ENGINEERING
COURSE: ELECTRICAL AND ELECTRONIC ENGINEERING
ACADEMIC YEAR: 2023/2024
TASK: TECHNICAL REPORT
FIRM: MUST ESTATES
STUDENT PARTICULARS
NAME
REG. NUMBER
KENEDY JUMANNE MTEGA
22100234020044
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SIGNATURE
Table of contents.
HISTORICAL BACKGROUND ........................................................................................................................... 3
Organization Structure ………………………………………………………………………………………………………………………….. 3
ELLECTRICAL ISTALLATION TESTING ............................................................................................... 4
THE ELECTRICAL TESTING IS DIVIDED INTO 2 PARTS .................................................................................... 5
Visual inspection ........................................................................................................................................... 5
Measurements……………………………………………………………………………………………………………………………………….4
THERE ARE 4 MAIN MEASUREMENTS REQUIRED ......................................................................................... 6
Earth .............................................................................................................................................................. 7
Insulation………………………………………………………………………………………………………………………………………………. 6
Continuity...................................................................................................................................................... 9
Polarity test……………………………………………………………………………………………………………………………………………. 9
Conclusion ................................................................................................................................................... 16
Reference .................................................................................................................................................... 17
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HISTORICAL BACKGROUND
Mbeya University of Science and Technology (MUST) is a result of the transformation of Mbeya
Institute of Science and Technology (MIST) through the University Act No. 7 of 2005 and the
charter of Mbeya University of Science and Technology, 2013. The Institute was a result of the
transformation of the former Mbeya Technical College (MTC) through the National Council for
Technical Education (NACTE) Establishment Order No. 9 of 2004 and Section 9 of the NACTE
Act of 1997. MTC was officially launched on 1st September, 1986. The transformation from
MTC to MIST and then MUST was done to fulfill a long-term plan, made during the first
phase Government, under the then President of the United Republic of Tanzania, the late
Mwalimu Julius Kambarage Nyerere. In a bid to expand and offer services to a wider client base,
in 2015, Mbeya University of Science and Technology (MUST) acquired a new Campus (MUST
Rukwa Campus College) which is in the Rukwa Region.
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ELLECTRICAL ISTALLATION TESTING
The risks linked to incorrect use of electricity may include:
-life-threatening danger for people,
-threat of damage to electrical installations and property,
-harmful effects on systems operation and equipment life spans.
So the purpose of electrical installation testing is primarily to ensure that people and goods are
kept safe and are protected in the event of a fault. It also facilitates preventive maintenance of
installations, preventing serious faults which might prove expensive (production shutdown, etc.).
To guarantee people's safety with regard to these installations and the electrical equipment
connected to them, standards have naturally been developed and updated to take changes into
account. The effectiveness of the safety measures implemented can only be guaranteed if regular
tests prove they are operating correctly. This is why the standards cover not only the initial
verifications when installations are commissioned, but also periodic testing whose frequency
depends on the type of installation and equipment, its use and the legislation in the country
involved. Ensuring user safety and reliable measurements.
Technically fault finding means testing electrical equipment to determine whether it is working
safely and correctly. Usually testing is done by electrician by using digital multimeter. Reason
for testing is Ability to fault finding and solve problems which confuse many others.
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THE ELECTRICAL TESTING IS DIVIDED INTO 2 PARTS
Visual inspection
To guarantee that the installation complies with the safety
requirements (presence of an earth electrode, protective devices, etc.) and does
not show any visible evidence of damage. Quality of visual inspection is dependent on the
experience and knowledge. Visual inspection should precede testing with instruments and the
installation being made live. It may be necessary to inspect some parts of an equipment or
installation during the construction phase. A checklist for a Domestic Installation might read as
follows:
Checklist for installation
a. Fixed Wiring
b. Flexible Cables and Cords
c. Terminations
d. Lighting Switches
e. Ceiling Roses
f. Trunking
g. Protection
h. Bonding
i. Socket Outlets
j. Joint Boxes
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Measurements
On completion of the visual inspection the following tests must be completed where applicable
they must be carried out in the following order.
A. Tests before connection of the installation to the supply
(a) Continuity of all protective conductors.
(b) Continuity of ring final circuit conductors
(c) Insulation Resistance of the electrical installation.
(d) Protection by separation of circuits
(e) Floor and wall resistance
(f) Polarity test.
(g) Electrical strength tests
B. Tests after connection of the installation to the supply
1. Automatic disconnection of supply including Earthing and bonding
2. Functional tests
 if the installation should fail any test, the fault must be rectified before any further testing is
done.
 That test and any preceding tests that may have been affected by the fault, should now be
repeated.
THERE ARE 4 MAIN MEASUREMENTS REQUIRED
(i) Earth
(ii) Insulation
(iii) Continuity
(iv) Tests of protective devices
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Earth
To guarantee safety on residential or industrial electrical installations, there must be
an earth electrode. If there is no earth electrode, it may endanger people's lives and damage
electrical installations and property. When a large enough area is available to set up stakes, you
should measure the earth with the traditional 3-pole method, also known as the 62 % method.
When the 62 % method is not applicable, however, other methods can be used. There are many
methods for measuring the earth, some more suitable than others, depending on the neutral
system, the type of installation (residential, industrial, urban, rural, etc.), the possibility of cutting
off the power, the area available for planting stakes, etc.
Procedures to measure earthing resistance
The following are the procedures for measuring earthing resistance:
 Prepare the equipment: Ensure that you have the necessary equipment for measuring
earthing resistance, including a digital earth tester, test leads, and auxiliary electrodes.
 Disconnect power: Before conducting any measurements, ensure that the power supply to
the earthing system is disconnected to prevent any potential hazards.
 Select the measurement method: There are two common methods for measuring earthing
resistance - the fall-of-potential method and the clamp-on method. Choose the
appropriate method based on the specific requirements and available equipment.
 Set up the test: Install the auxiliary electrodes at the designated locations around the
earthing system. The number and placement of electrodes depend on the size and
configuration of the grounding system.
 Connect the equipment: Connect the test leads from the digital earth tester to the auxiliary
electrodes and the grounding system being measured.
 Perform the measurement: Follow the instructions provided by the manufacturer of the
digital earth tester to perform the measurement. This typically involves injecting a known
current into the grounding system and measuring the voltage drop across the electrodes.
 Record the readings: Take multiple readings at different locations and average them to
obtain an accurate measurement of the earthing resistance.
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 Calculate the resistance: Use the readings obtained from the digital earth tester to
calculate the earthing resistance using the appropriate formula or software provided by
the manufacturer.
 Evaluate the results: Compare the measured resistance with the acceptable limits
specified by relevant standards or regulations. If the resistance is within the acceptable
range, the Earthing system is considered to be effective. If not, further investigation and
corrective actions may be required.
 Document the results: Record all the measurement data, including the location, date, and
time of the measurement, as well as the calculated Earthing resistance. This
documentation will be useful for future reference and maintenance purposes.
Figure 1: earth resistance test.
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Continuity
The purpose of continuity measurement is to check the continuity of the protective
conductors and the main and supplementary equipotential bonds. The test is carried
out using a measurement instrument capable of generating a no-load voltage of 4 to
24 V (DC or AC) with a minimal current of 200 mA. The resistance measured must be lower
than a threshold specified by the standard applicable to the installation tested, which is usually 2
Ω. As the resistance value is low, the resistance of the measurement leads must be compensated,
particularly if very long leads are used.
The following are the procedures for measuring earthing resistance:
 Prepare the equipment: Ensure that you have the necessary equipment for measuring
earthing resistance, including a digital earth tester, test leads, and auxiliary electrodes.
 Disconnect power: Before conducting any measurements, ensure that the power supply to
the earthing system is disconnected to prevent any potential hazards.
 Select the measurement method: There are two common methods for measuring earthing
resistance - the fall-of-potential method and the clamp-on method. Choose the
appropriate method based on the specific requirements and available equipment.
 Set up the test: Install the auxiliary electrodes at the designated locations around the
earthing system. The number and placement of electrodes depend on the size and
configuration of the grounding system.
 Connect the equipment: Connect the test leads from the digital earth tester to the auxiliary
electrodes and the grounding system being measured.
 Perform the measurement: Follow the instructions provided by the manufacturer of the
digital earth tester to perform the measurement. This typically involves injecting a known
current into the grounding system and measuring the voltage drop across the electrodes.
 Record the readings: Take multiple readings at different locations and average them to
obtain an accurate measurement of the earthing resistance.
 Calculate the resistance: Use the readings obtained from the digital earth tester to
calculate the earthing resistance using the appropriate formula or software provided by
the manufacturer.
 Evaluate the results: Compare the measured resistance with the acceptable limits
specified by relevant standards or regulations. If the resistance is within the acceptable
range, the earthing system is considered to be effective. If not, further investigation and
corrective actions may be required.
 Document the results: Record all the measurement data, including the location, date, and
time of the measurement, as well as the calculated earthing resistance. This
documentation will be useful for future reference and maintenance purposes.
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Figure 2: continuity test of final ring circuit.
III. Insulation
Good insulation is essential to prevent electric shocks. This measurement, usually
carried out between active conductors and the earth, involves injecting a DC voltage,
measuring the current and thus determining the insulation resistance value. The power must be
switched off and the installation must be disconnected before performing this test to ensure that
the test voltage will not be applied to other equipment electrically connected to the circuit to be
tested, particularly devices sensitive to voltage surges.
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The procedure for measuring insulation resistance in an electrical installation typically
involves the following steps:
 Ensure safety: Before starting the measurement, ensure that the electrical installation is
de-energized and isolated from the power source to prevent any potential hazards.
 Select appropriate equipment: Use a high-quality insulation resistance tester or
megohmmeter that is suitable for the voltage level and insulation resistance range of the
installation being tested.
 Prepare the installation: Remove any connected equipment or devices from the circuit
under test. Ensure that all switches and circuit breakers are in the open position.
 Connect the tester: Connect the test leads of the insulation resistance tester to the
installation being tested. The positive lead is connected to the live conductor, and the
negative lead is connected to the earth or ground.
 Set the test voltage: Set the test voltage on the insulation resistance tester according to the
specifications of the installation being tested. Common test voltages include 250V, 500V,
and 1000V.
 Perform the measurement: Activate the insulation resistance tester and allow it to
stabilize. Then, initiate the measurement by pressing the appropriate button or switch.
The tester will apply the test voltage and measure the insulation resistance.
 Record the results: Once the measurement is complete, record the insulation resistance
value displayed on the tester. Repeat the measurement at different points in the
installation if necessary.
 Interpret the results: Compare the measured insulation resistance values with the
recommended minimum values specified by relevant standards or regulations. Lower
insulation resistance values may indicate insulation degradation or faults in the
installation.
 Take necessary actions: If the measured insulation resistance values are below the
acceptable range, further investigation and corrective actions should be taken to identify
and rectify any insulation faults or issues in the electrical installation.
 Document the test: Finally, document the test results, including the measured insulation
resistance values, test voltage, date, and any additional observations or actions taken
during the testing process. This documentation will serve as a record for future reference
and maintenance purposes.
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Figure 3: insulation resistance between live conductor and earth
Method
them and the protective conductor.
high resistance reading would be ideal
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Figure 4: insulation resistance test between live conductors
Method
ideal.
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IV. Polarity test
This test is carried out to ensure that:
 Polarity at the main supply point is correct.
 The phase conductor is connected to fuses, single pole circuit breakers
and switches.
 Incoming supply is connected to back contact of screw in type fuses.
 The phase conductor is connected to the center contact of (Edison screw)
ES type lamp holders .
 All wiring is correctly connected at socket outlets and other similar
accessories.
Since continuity of the protective conductor has already been verified.
This test can be completed in basically the same manner/procedures.
i. Ensure that all appliances, lamps etc. are unplugged or otherwise removed.
ii. With the circuit MCB in the “off” position, connect one end of the long trailing lead to the
outgoing terminal of the circuit MCB. Using the other end in conjunction with the test
meter leads, take readings from the phase terminal of all the points around the circuit e.g.
switches, luminaries, sockets etc.
iii. Continuity (approx. resistance of conductor involved) at each outlet ensures that polarity
iv. is correct.
v. If the supply is disconnected from the installation the long trailing lead may be connected
to the phase bus bar and the MCB should then be left in the “on” position.
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Figure 5: Polarity test of socket circuity.
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Conclusion.
In conclusion, earth resistance, continuity test, insulation resistance test, and polarity test are
essential components of electrical installations.
Earth resistance testing is crucial to ensure the integrity of the grounding system, which is
essential for the safety of electrical installations and protection against electrical faults. It helps
identify any potential faults or issues with the grounding system, allowing for timely repairs and
maintenance.
Continuity testing is used to verify the presence of a complete electrical path between two points.
It ensures that electrical circuits are properly connected, preventing any interruptions or faults
that could lead to malfunctions or safety hazards.
Insulation resistance testing measures the resistance of electrical insulation materials, such as
wires and cables, to the flow of electrical current. It helps identify any deterioration or damage to
the insulation, which can lead to electrical leakage or short circuits. Regular insulation resistance
testing is crucial for maintaining the safety and efficiency of electrical installations.
Polarity testing is performed to ensure that the correct connection of live, neutral, and earth wires
is maintained in electrical installations. It helps prevent electrical shocks and ensures the proper
functioning of electrical devices and equipment.
Overall, these tests are vital for ensuring the safety, efficiency, and proper functioning of
electrical installations. Regular testing and maintenance of these parameters are essential to
prevent electrical hazards, malfunctions, and costly repairs.
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Reference
www.academia.com
www.scribd.com
www.electricalengineeringportal.com
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