Portable Appliance Testing (PAT) is the term used to describe the examination and inspection of electrical appliances to ensure they are in a safe and usable condition.
The formal term for the process is "in-service inspection & testing of electrical equipment". Testing involves a visual inspection of the equipment and any flexible cables for good condition, and also where required, verification of earthing (grounding) continuity, and a test of the soundness of insulation between the current carrying parts, and any exposed metal that may be touched. The formal limits for pass/fail of these electrical tests vary somewhat depending on the category of equipment being tested.
Visual testing alone is not enough to pick-up some electrical problems that may lead to fire or electrocution.
Under ‘The Electricity at Work Regulations 1989’ it is a requirement that all electrical equipment in the workplace that has the potential to cause injury or harm is maintained in a safe condition. This includes a regime of Portable Appliance Testing
However, the regulations do not specify what needs to be done or how frequently, but good practice is to have equipment examined and inspected every twelve months for peace of mind as an employer know you have put your employee’s safety first.