Portable appliance testing: Items inspected by type and use.
Portable appliance testing (PAT) is the term used to describe the examination of electrical appliances and equipment to ensure they are safe to use. Most electrical safety defects can be found by visual examination, but some types of defect can only be found by testing. However, it is essential to understand that visual examination is an essential part of the process because some types of electrical safety defect can't be detected by testing alone.
The Electricity at Work Regulations 1989 require that any electrical equipment that has the potential to cause injury is maintained in a safe condition. However, the Regulations do not specify what needs to be done, by whom or how frequently (i.e. they don't make inspection or testing of electrical appliances a legal requirement, nor do they make it a legal requirement to undertake this annually).
But as with every inspection regime you would follow advice of a competent person and a Risk assessment.