The qualified engineer will be assessing the overall quality, performance and safety of an electrical installation. They will be looking out, especially for any deterioration or defects. All will be based on electrical requirements of BS7671 Wiring Regulations and procedures presented in 2391 inspection and testing guidance.
The first stage of the test is normally a visual assessment. Accessories and consumer unit will be inspected to see if anything is clearly in need of repair or replacement. There might be breaks or cracks in electrical equipment and accessories. There also may be obvious signs of overheating, in which case the equipment will need replacing. In older properties, sometimes the distribution board may be very old and not compliant with current regulations in which case it may require a replacement for a new consumer unit with an RCD protection. This electrical upgrade offers far greater protection with RCD, and Earth leakage monitors that trip when a fault occurs.