When working on any existing electrical system the first test to be carried out should be?

When working on any existing electrical system, the first test to be carried out should be a thorough visual inspection to identify any obvious signs of damage, wear, or improper installation. Following this, it is critical to perform a continuity test to ensure that the circuit is complete and functioning properly. This step helps to verify the integrity of the wiring and connections before proceeding with any further testing or maintenance.