Class I and Class II describe how electrical equipment protects against electric shock. They help a competent person select an appropriate inspection and test approach. Check the equipment’s markings and manufacturer information rather than guessing from its appearance.
Class I equipment combines basic insulation with protective earthing. The protective conductor provides a safety connection for exposed conductive parts that could become live following an insulation fault.
Many desktop computers, washing machines and refrigerators are Class I, but an example is not a substitute for checking the actual model. Appropriate inspection and testing may include checking the protective conductor and insulation.
Class II equipment uses double or reinforced insulation for protection and does not rely on a protective earth connection. Look for the square-within-a-square symbol and confirm the manufacturer’s information.
A UK Class II appliance can still have a three-pin plug. The presence of an earth-position pin does not, by itself, prove a protective earth connection. Some Class II plugs use an insulated shutter-opening pin.
Phone chargers, power supplies and hair dryers may be Class II. Classify the individual product, not the whole product category.
A laptop’s mains power supply may have a different classification from the laptop it supplies. A detachable mains lead also needs to be considered separately.
Incorrect classification can lead to unsuitable tests or an important safety check being missed. The test method must suit the equipment, its construction and manufacturer instructions. Do not remove an earth connection to make equipment appear to pass a different test.
Keep an equipment inventory and make the item, rating plate, plug and lead accessible during inspection. Flag damaged, modified or unidentified equipment to the tester.
For an AiO quotation, count each detachable mains lead separately. A battery-powered laptop body is not counted as a mains appliance; its mains power supply and detachable mains lead are separate test items where both are present. Our illustrated counting guide explains this distinction.
See our PAT report and appliance label examples to understand how equipment and findings are recorded.
Technical references: Seaward’s explanation of appliance classes and Electrical Safety First’s guidance on equipment classes. For the safety features of UK plugs, explore our UK plug guide and interactive challenge.
Class I relies on protective earthing alongside insulation; Class II uses double or reinforced insulation without relying on protective earthing.
No. Damage and deterioration still matter. The competent person chooses checks appropriate to the equipment and its use.
Class alone does not set the interval. Consider the equipment, environment, handling and previous findings. There is no blanket annual PAT requirement. Read our testing-frequency guide.
No. Being fixed or permanently connected does not remove the need to manage its safety. The inspection scope and competence needed may differ from a routine plug-in appliance visit.
Do not disconnect or remove protective earthing. Classification depends on the product’s design, not a change made to its plug.
Get your PAT testing quote or speak to AiO about unusual equipment.
View our example report and appliance labels before you book.