Class I and Class II appliances: what is the difference?
The class of an appliance is about how it protects you from electric shock. It also decides which tests it gets.
Class I: protected by the earth
Class I appliances have basic insulation plus a connection from any exposed metal parts to the earth pin of the plug. If a live wire comes loose and touches the metal, the fault current flows to earth and blows the fuse or trips the circuit instead of passing through you. That only works if the earth path is sound, which is why HSE recommends that Class I equipment has a test to check the earth connection.
Typical Class I items: kettles, toasters, irons, microwaves, fridges, washing machines, many desktop PC towers and most heaters with metal bodies.
Class II: double insulated
Class II appliances have an extra layer of insulation, so live parts cannot reach anything you can touch even if there is a fault. They do not need an earth connection, and usually have a two-core cable. Look for the symbol on the rating plate: one square drawn inside another.
Typical Class II items: hairdryers, most power tools, table lamps, televisions, laptop and phone chargers, and many small kitchen appliances with plastic bodies.
Is a kettle Class 1 or Class 2?
Almost always Class I, even when the body is plastic. The heating element and the connector on the base are earthed, and the base has an earth pin. Check the rating plate underneath: if there is no double-square symbol, treat it as Class I.
How the class changes the test
| Check | Class I | Class II |
|---|---|---|
| Formal visual inspection | Yes | Yes |
| Earth continuity test | Yes | No earth to test |
| Insulation or leakage test | Yes | Yes, where testing is needed |
| Functional check | Yes | Yes |
HSE's suggested starting intervals for low-risk workplaces reflect the difference. Class I items such as kettles, irons and some kitchen equipment get user checks, a formal visual inspection every six months to a year and a combined inspection and test every one to two years. Class II items that are not hand-held and rarely move, such as fans and table lamps, need a visual inspection every two to four years and no routine test. Hand-held Class II items fall in between.
What about Class III?
Class III equipment runs at a safe extra-low voltage from a separate supply, such as some low-voltage lighting and battery-powered kit. The item itself is not tested, but the charger or transformer that feeds it from the mains is.
Sources
Common questions
Is a hairdryer Class 1 or Class 2?
Nearly all modern hairdryers are Class II, with a double-square symbol on the rating plate. They still get a visual inspection, and because they are hand-held and used near water, they are worth checking regularly.
Does Class II mean it never needs checking?
No. Double insulation only protects you while it is intact. A cracked casing or a damaged cable defeats it, which is why Class II items still get visual inspections.
How do I find out an appliance's class?
Look at the rating plate or the instructions. The double-square symbol means Class II. If there is no symbol and the plug has an earth connection, treat it as Class I.
Related guides
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HSE says new equipment should arrive safe and does not need a formal PAT test. What to check instead, and when testing a new item still makes sense.
Read the guideExtension leads and adaptors: the items most likely to fail
Why extension leads and adaptors fail PAT tests more than anything else, how to avoid overloading them, and what HSE says about testing them.
Read the guideWhat a PAT certificate should show
The law does not require a PAT certificate, but insurers, agents and inspectors ask for one. What a useful record contains, and how to spot a weak one.
Read the guideReady to get tested?
Pick a slot in the next four weeks, or send us the details for a date further out. It's a provisional booking, and one of the team will be in touch to confirm.