Outline four tests carried out in a completed electrical installation and in each case name the test instrument used?

1. Insulation resistance test: This test is carried out to ensure that there are no faults in the insulation of the electrical wiring. The test instrument used is a megohmmeter or insulation resistance tester.

2. Earth continuity test: This test is conducted to verify the continuity of the earth connection in the electrical installation. The test instrument used is a continuity tester or a multimeter set to the continuity mode.

3. Polarity test: This test is performed to confirm that the correct polarity is maintained throughout the electrical installation. The test instrument used is a digital multimeter or a polarity tester.

4. Earth loop impedance test: This test is carried out to determine the impedance of the earth loop in the electrical installation, which is crucial for ensuring the effectiveness of the earthing system. The test instrument used is an earth loop impedance tester.