III in a diamond (Class III, safety extra-low voltage)
Class III equipment: it is meant to run on safety extra-low voltage (SELV), and that low supply voltage is what protects against electric shock.
Symbol reference: IEC 60417-5180
A mark tells you what the maker declares, never that the product is safe.
- What it looks like
- A square standing on one corner, like a diamond, with the Roman numeral III inside.
- Who may apply it
- The manufacturer, for equipment meeting the Class III requirements of IEC 61140.
What it does not promise
It covers the device, not whatever feeds it: the protection depends on the supply really being a safety extra-low voltage source, and that power unit carries its own marks. Equipment designed for less than 50 V AC or 75 V DC is outside the scope of the EU Low Voltage Directive.
Other marks with the same shapes
CE markingConformity markUKCA markingConformity markUKNI markingConformity markDouble square (Class II, double insulated)IEC 60417-5172Crossed-out bin on a battery, with Cd, Pb or HgThe crossed-out wheeled bin printed on a battery,…Roman numeral on a power supply (efficiency level, e.g. VI)A Roman numeral from I to VII, often VI, on the power…
Sources
Each page below was fetched and read on the date shown. Where a symbol’s IEC 60417 or ISO 7000 number is given, a public page listing that number is among them.
- Wikimedia Commons: File page transcribing IEC 60417 entry 5180 (title, function, publication) — Symbol 5180 from IEC 60417, “Class III equipment”: to identify equipment meeting the safety requirements specified for class III according to IEC 61140. Additional information: SELV. Checked 2026-09-24.
- EUR-Lex (Official Journal of the EU): Directive 2014/35/EU (Low Voltage Directive) — Article 1, Article 17 and Annex III — Article 1: the Directive applies to electrical equipment designed for use with a voltage rating of between 50 and 1 000 V AC and between 75 and 1 500 V DC. Checked 2026-09-24.
Written in our own words; quotations are the sources’ wording.