Double insulated (Class II)
Double insulated (Class II)
The appliance is protected by two layers of insulation and needs no earth connection.
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What it looks like
A small square drawn inside a larger square, moulded into the casing or printed on the rating plate.
What it means
Two independent layers, or one reinforced layer, mean a single insulation failure cannot make the casing live. That is why a Class II appliance legitimately has a two-pin plug or a two-core flex, and why fitting an earth wire to one is wrong rather than cautious — there is no earth terminal inside to attach it to. Hairdryers, phone chargers, most power tools and nearly all plastic-bodied appliances are Class II. If the symbol is present, an unearthed lead is not a fault.
Defined by IEC 60417-5172 / IEC 61140. Where a symbol differs between standards, the difference is described above rather than resolved — both versions are in circulation on real labels.
Other electrical and appliance symbols
| Symbol | Means |
|---|---|
| CE mark | The manufacturer declares the product meets the EU rules that apply to it. |
| UKCA mark | The manufacturer declares the product meets Great Britain's rules — the British counterpart to CE. |
| UL Listed | A complete product tested by Underwriters Laboratories against its safety standard. |
| UL Recognized Component | A component certified for use inside a larger product — not a certification of the finished item. |
| FCC mark | The device meets US limits on radio-frequency interference. |
| RoHS compliant | The product restricts ten hazardous substances, including lead, mercury, cadmium and four phthalates. |
| Crossed-out wheelie bin (WEEE) | Do not put this in household waste — take it to a separate collection for electrical items or batteries. |
| Crossed-out bin with Pb, Cd or Hg | A battery for separate collection which also contains lead, cadmium or mercury above the reporting threshold. |
| Protective earth (ground) | This terminal must be connected to the protective earth conductor. |
| IP rating (IP67, IPX4) | How well the enclosure keeps out solids and water. First digit solids 0–6, second digit water 0–9. |
| EU energy label (A to G) | How efficient the appliance is, on a scale from A to G, alongside consumption figures. |
| EnergyGuide label (US) | The estimated annual energy cost of this appliance in the US, and how it compares with the range for its class. |
| Alternating current (AC) | Alternating current. On a power supply it marks the mains input side. |
| Direct current (DC) | Direct current. On a power supply it marks the output side. |
| Barrel jack polarity (centre positive or centre negative) | Which conductor of a barrel plug is positive: the inner pin or the outer sleeve. |
Common questions
- What does the double insulated (class ii) symbol mean?
- The appliance is protected by two layers of insulation and needs no earth connection.
- What does it look like?
- A small square drawn inside a larger square, moulded into the casing or printed on the rating plate.
Related pages
- Protective earth (ground) This terminal must be connected to the protective earth conductor.
- CE mark The manufacturer declares the product meets the EU rules that apply to it.
- IP rating (IP67, IPX4) How well the enclosure keeps out solids and water. First digit solids 0–6, second digit water 0–9.
- CE mark The manufacturer declares the product meets the EU rules that apply to it.
- UKCA mark The manufacturer declares the product meets Great Britain's rules — the British counterpart to CE.
- UL Listed A complete product tested by Underwriters Laboratories against its safety standard.
- UL Recognized Component A component certified for use inside a larger product — not a certification of the finished item.
- FCC mark The device meets US limits on radio-frequency interference.
- RoHS compliant The product restricts ten hazardous substances, including lead, mercury, cadmium and four phthalates.
- Crossed-out wheelie bin (WEEE) Do not put this in household waste — take it to a separate collection for electrical items or batteries.
- Crossed-out bin with Pb, Cd or Hg A battery for separate collection which also contains lead, cadmium or mercury above the reporting threshold.
- Protective earth (ground) This terminal must be connected to the protective earth conductor.
- IP rating (IP67, IPX4) How well the enclosure keeps out solids and water. First digit solids 0–6, second digit water 0–9.
Sources
- Official vendor product documentation — At One Place