Portable Appliance Testing (PAT) is the process of checking electrical appliances and equipment to confirm they are safe to use. The process combines a visual inspection with a series of electrical measurements made using a dedicated PAT testing instrument.
Businesses and organisations use inspection and testing to help maintain electrical equipment safely. The general workplace duty does not make a particular PAT test mandatory for every appliance.
There is no single fixed requirement in UK law specifying how often PAT testing must take place for all types of equipment, but health and safety legislation requires employers and landlords to ensure that electrical equipment is maintained in a safe condition. PAT testing provides documented evidence that appliances have been checked and found to meet the required electrical safety criteria at the time of the test.
The process begins with a visual inspection of each appliance, its cable and its plug. This stage identifies obvious signs of damage such as fraying or cracking of cable sheaths, damaged plugs, loose connections, signs of overheating or modifications that may have compromised safety.
Appliances with visible damage that presents a clear hazard are set aside at the visual inspection stage without proceeding to electrical testing. Where electrical testing is appropriate, the engineer selects suitable tests for the equipment; some equipment needs only a visual examination.
These typically include an earth continuity check for Class I appliances with an earth connection, an insulation resistance check and, for certain appliance types, an protective-conductor or touch-current measurement. The combination of tests applied depends on the class and type of appliance.
Each appliance receives a pass or fail outcome. Items that pass are labelled with the date of the test.
Items that fail are labelled to indicate they should be removed from use until repaired or replaced. A written record of all appliances tested and their outcomes is provided at the end of the session.
Typical locations where PAT testing is commonly carried out include offices, schools, care homes, hospitality venues and rental properties. The appropriate frequency of testing depends on the type of equipment, its operating environment and how intensively it is used.