The legislation requires that the electrical infrastructure must be maintained so that it remains safe. Guidance is given on the frequency of electrical examinations - it is a matter of judgement on the part of the duty holder to decide on what level of maintenance is required; this should be determined by conducting a risk assessment - the electrical distribution information required to make such an assessment will be contained in the Electrical Distribution Information System (EDIS).

Further details can be obtained from http://www.hse.gov.uk/electricity/information/law.htm