---
title: "Double insulated (Class II) — what it means"
description: "The appliance is protected by two layers of insulation and needs no earth connection. What the symbol looks like, what happens if you ignore it, and where its meanin"
url: https://atoneplace.net/symbol/electrical-double-insulated/
site: "At One Place"
---

# Double insulated (Class II)

**Double insulated (Class II): The appliance is protected by two layers of insulation and needs no earth connection.**

⧈

## 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)](https://atoneplace.net/symbol/electrical-protective-earth/)
- [CE mark](https://atoneplace.net/symbol/electrical-ce/)
- [IP rating (IP67, IPX4)](https://atoneplace.net/symbol/electrical-ip-rating/)
- [CE mark](https://atoneplace.net/symbol/electrical-ce/)
- [UKCA mark](https://atoneplace.net/symbol/electrical-ukca/)
- [UL Listed](https://atoneplace.net/symbol/electrical-ul-listed/)
- [UL Recognized Component](https://atoneplace.net/symbol/electrical-ul-recognized/)
- [FCC mark](https://atoneplace.net/symbol/electrical-fcc/)
- [RoHS compliant](https://atoneplace.net/symbol/electrical-rohs/)
- [Crossed-out wheelie bin (WEEE)](https://atoneplace.net/symbol/electrical-weee/)
- [Crossed-out bin with Pb, Cd or Hg](https://atoneplace.net/symbol/electrical-battery-bin/)
- [Protective earth (ground)](https://atoneplace.net/symbol/electrical-protective-earth/)
- [IP rating (IP67, IPX4)](https://atoneplace.net/symbol/electrical-ip-rating/)

## Sources

- Official vendor product documentation — At One Place (/about/)