When it comes to PAT testing, the class of an appliance determines which tests need to be carried out.
What Is a Class I Appliance?
A Class I appliance relies on basic insulation plus an earth connection for safety. If the insulation fails, the earth connection provides a safe path for the fault current. Class I appliances have a three-core cable and a three-pin plug with an earth pin.
Examples: kettles, toasters, washing machines, desktop computers, microwaves.
What Is a Class II Appliance?
A Class II appliance (also called double insulated) relies on two layers of insulation for safety. It does not need an earth connection. Class II appliances are marked with a small square-within-a-square symbol.
Examples: phone chargers, laptop power supplies, hair dryers, many modern power tools, desk fans.
How Does This Affect PAT Testing?
- Class I: Visual inspection + earth continuity test + insulation resistance test
- Class II: Visual inspection + insulation resistance test (no earth test needed)
Why Does It Matter?
Applying the wrong test to the wrong class produces misleading results. A competent PAT tester will identify the appliance class before testing. This is one reason why professional PAT testing is preferable to DIY approaches.
Not sure about the appliances in your workplace? Contact us and we will advise you.
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