Electrical installations will deteriorate over time. Safety standard are improved as new technology advances. Like the MOT test on you car, it is recommended that electrical installations are professionally inspected and tested periodically (every 10 years for a house, more frequency for business premises) to ensure that they remain safe for continued use.
A lot can also be learned from a simpler visual only inspection of key parts on the installation, such as the fuse box.
The inspection report will identify issues that require repair or upgrade, or where there is immediate danger.