Protective earth (ground)
Protective earth (ground)
This terminal must be connected to the protective earth conductor.
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What it looks like
A circle enclosing a line that descends to three horizontal bars of decreasing length, like a stack of plates.
What it means
Distinct from the plain earth symbol, which is the same stack of bars without the circle and marks a functional or signal ground rather than a safety one. A Class I appliance depends on this connection: if the live conductor touches the metal casing, the earth path carries enough current to trip the protective device instead of leaving the case at mains voltage. Disconnecting it — for instance with a two-pin travel adaptor on an earthed appliance — removes the protection silently, because the appliance goes on working normally.
Defined by IEC 60417-5019. 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. |
| Double insulated (Class II) | The appliance is protected by two layers of insulation and needs no earth connection. |
| 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 protective earth (ground) symbol mean?
- This terminal must be connected to the protective earth conductor.
- What does it look like?
- A circle enclosing a line that descends to three horizontal bars of decreasing length, like a stack of plates.
Related pages
- Double insulated (Class II) The appliance is protected by two layers of insulation and needs no earth connection.
- 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.
- 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.
- Double insulated (Class II) The appliance is protected by two layers of insulation and needs no earth connection.
- 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