Vertical line (on, I)
On: the switch position that connects the equipment to the mains.
Symbol reference: IEC 60417-5007
A mark tells you what the maker declares, never that the product is safe.
- What it looks like
- A single short vertical line, usually on one end of a rocker switch and often read as “I”.
- Who may apply it
- The equipment maker, on mains switches or their positions, and in every case where safety is involved.
What it does not promise
It marks a switch position, nothing more. It says nothing about the voltage or the load. The IEC also notes that the symbol’s meaning depends on its orientation, so a horizontal line is not the on symbol.
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 5007 (title, function, notes) — Symbol 5007 from IEC 60417, “ON” (power): to indicate connection to the mains, at least for mains switches or their positions, and all those cases where safety is involved; the meaning depends upon its orientation. Checked 2026-09-24.
- Unicode Consortium: Unicode Character Database, NamesList.txt — U+23FB to U+23FE and U+2B58 — U+23FD POWER ON SYMBOL; “use 2B58 for power off symbol”. Checked 2026-09-24.
Written in our own words; quotations are the sources’ wording.