Portable appliance testing (commonly known as “PAT”, “PAT inspection” or “PAT testing”) is the name of a process in the United Kingdom[ the Republic of Ireland, New Zealand and Australia by which electrical appliances are routinely checked for safety. 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.
Carrying out PAT
This can be done by hiring an external company to test all the electrical products in a business (someone who has had some PAT training, either by an official qualification or by attending a health and safety course offered by some electrical health and safety companies) or it can be done in-house by a competent person. In a low-risk environment most dangerous defects can be found simply by checking the appliances for obvious signs of damage such as frayed cables.
Advising the user of potential danger signs can result in problems being picked up before they can result in any danger. For example, if the power cable is frayed or the plug is cracked, users need to be advised not to use the appliance and report the fault to a supervisor. This information can be put across, say by the use of a poster or in a memo. User checks are always carried out before the operation, and the results are generally not recorded unless a defect is identified.
Formal visual inspections
This is a process of simply inspecting the appliance, the cable and the plug for any obvious signs of damage. According to the HSE, this process can find more than 90% of faults.
Combined inspections and PAT
At periodic intervals, the portable appliances are tested to measure that the degree of protection to ensure that it is adequate. At these intervals, a formal visual inspection is carried out and then followed by PAT testing. Note the inside of the plug should be checked unless it is moulded or there is an unbroken seal covering the screws (bad internal wiring or an unsuitable fuse would cause the item to be classed as dangerous).