Every existing electrical installation, even it has been initially inspected, should be regularly inspected.
Although is true that electrical installations do not deteriorate quickly, and therefore do not require much maintenance, they do not however retain their original condition: damage, corrosion, degradation of material, degradation of the insulation (the insulation hardens and it can crack), connections become loose, excessive electrical loading, ageing, environmental influences, normal wear and tear, ...
Apart from deterioration over the years, the functionality of the electrical installations does not follow the ever-changing needs of its occupants.
Periodic inspections should comprise a detailed examination of the installation. They can be carried out without dismantling, or with partial dismantling the electrical installation.
A periodic inspection will reveal if any of the electrical circuits are overloaded (and thus that more circuits should be provided) and will reveal other potential electrical shock risks and fire hazards in the electrical installation.
It is recommended that electrical installations in homes be thoroughly inspected at least every 10 years. Every 5 years a lighter inspection could be carried out and if it is not possible to inspect all parts of the installation, a sampling should be carried out.
Periodic inspections can also be carried out when a property is going to be let or sold, or after a change of ownership.