3.3 Inspection and Testing 4

• Meaning of inspection and testing of electrical installations
• Reasons for inspecting and testing installations before commissioning
• The instruments used: ohmmeter, megger, earth loop tester and test lamp
• The continuity test and how to read its results
• The insulation resistance test and the minimum acceptable value
• Earthing tests: earth continuity, earth electrode resistance and loop impedance
• The polarity test and the importance of correct polarity
• Analysing open circuit, short circuit and earth faults
• Preparing an inspection and testing report
• Commissioning a tested installation and its importance

• explain the difference between inspection and testing
• describe the types of tests performed on domestic electrical installations
• perform electrical tests on domestic installations
• prepare an inspection and testing report for a domestic installation
• appreciate the importance of inspection and testing of an electrical installation

“Why are electrical installations inspected and tested before commissioning?”

“How is testing and inspection carried out?”

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1. Inspection and testing of installations
   40 min · 1 practice tasks · quiz
   Introduce inspection and testing and explain how the two activities differ.
2. Reasons for inspection and testing
   40 min · 1 practice tasks · quiz
   Explain why installations are inspected and tested, linking the work to safety and the national regulations.
3. Instruments used for testing
   40 min · 1 practice tasks · quiz
   Identify the ohmmeter, insulation resistance tester, earth loop tester and test lamp and state what each is used for.
4. Carrying out a visual inspection
   40 min · 1 practice tasks · quiz
   Inspect an installation safely by looking and checking each item against a checklist.
5. The continuity test
   40 min · 1 practice tasks · quiz
   Carry out a continuity test with an ohmmeter and interpret the reading.
6. The insulation resistance test
   40 min · 1 practice tasks · quiz
   Test insulation resistance with a megger and judge the result against the minimum value.
7. Earthing tests
   40 min · 1 practice tasks · quiz
   Describe earth continuity, earth electrode resistance and earth fault loop impedance tests.
8. The polarity test
   40 min · 1 practice tasks · quiz
   Test that line, neutral and earth are connected in the correct positions.
9. Analysing open and short circuit faults
   40 min · 1 practice tasks · quiz
   Use test results to identify open circuits, short circuits and earth faults.
10. Preparing an inspection and testing report
    40 min · 1 practice tasks · quiz
    Record findings in an inspection and testing report with observations and recommendations.
11. Commissioning and the importance of testing
    40 min · 1 practice tasks · quiz
    Explain how a tested installation is commissioned and why inspection and testing matter.