Portable Appliance Testing (PAT) is a process that ensures your electrical equipment is safe for your employees and customers. It generally consists of a visual inspection of the device plus an electrical test. The Health & Safety Executive does not give a specific interval as to how often you should have your equipment checked. The IEE guidance offers different periods depending on the business (e.g. a commercial kitchen should have its appliances checked every six months, whereas a school should check every year), though in practice, many insurance companies prefer you to run an annual inspection.