Functional earth (earth under an arch)
Marks a functional earthing terminal: an earth used to make the equipment work properly, for example with a specially designed earthing system that stops the equipment malfunctioning. It is not there for protection against electric shock.
Symbol reference: IEC 60417-5018
A mark tells you what the maker declares, never that the product is safe.
- What it looks like
- The earth sign, a vertical line over three shrinking bars, under an open half-circle.
- Who may apply it
- The equipment maker, on the terminal meant for the functional earth.
What it does not promise
It is not the safety earth. The IEC keeps the two apart: 5019 is for protection against shock in a fault, 5018 is to avoid malfunction. Do not treat this terminal as the protective earth.
Other marks with the same shapes
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 5018 (title, function, notes) — Symbol 5018 from IEC 60417, “Functional earthing; functional grounding (US)”: to identify a functional earthing terminal, for example of a specially designed earthing system to avoid causing malfunction of the equipment. Checked 2026-09-24.
- Wikimedia Commons: File page transcribing IEC 60417 entry 5019 (title, function, publication) — Symbol 5019 from IEC 60417, protective earth: for connection to an external conductor for protection against electric shock in case of a fault. Checked 2026-09-24.
Written in our own words; quotations are the sources’ wording.