Which three core tests are typically performed to verify an electrical installation during commissioning?

• A. Continuity, insulation resistance, and polarity tests
• B. Continuity, insulation resistance, and earth fault loop impedance tests
• C. Polarity, earth fault loop impedance, and RCD tests
• D. Continuity, insulation resistance, and RCD tests

Answer: (A)

The main idea here is to confirm that the wiring is intact and correctly connected before the system is energized. The trio of tests used for this checks three essential aspects of the wiring.

Continuity verifies that every conductor runs from its origin to its destination without breaks, so there’s a continuous current path from the supply to outlets or fixtures. This catches any hidden breaks, loose connections, or damaged conductors.

Insulation resistance checks that the insulation around conductors is in good condition and not allowing leakage paths to earth or between live conductors. A high insulation resistance reading indicates the insulation is sound and unlikely to fail under normal operation.

Polarity ensures that live and neutral are connected to the correct terminals at outlets and devices, and that the protective earth is correctly wired. Correct polarity prevents shock hazards and ensures devices operate as intended.

While other tests (like earth fault loop impedance or RCD tests) are also important and performed during commissioning, these three focus on confirming basic wiring integrity and correct connections, which is why they’re considered the core set.