I think BS7671 (IEE Wiring Regs) would recommend 5 years for installations in the common areas, or more frequently if the environment is hostile. Heres a very short extract from Modern Wiring Practice by Steward and Stubbs
"The determination of the frequency of periodic inspection is covered by lEE Regulation 732-01-01. No specific period is laid down, and an assessment needs to be made as to the use of the installation, the likely frequency of maintenance, and the possible external influences likely to be encountered. The person carrying out the inspection and testing, and completing the inspection certificate needs to take account of these issues. In the absence of other local or national regulations, a maximum period of five years would be applied, with shorter periods where appropriate"