If you run a business you have a duty of care for the safety of everyone who uses your work premises... even if you are a sole trader. To meet your responsibilities you need to carry out regular electrical inspecting and testing of all appliances, something which could also be an insurance requirement.
PAT testing or portable appliance testing is the standard electrical inspecting and testing procedure required to meet current health and safety legislation. It applies to everything from computers to fridges, extension leads to routers.
PAT testers for the small business market