A power symbol is a symbol indicating that a control activates or deactivates a particular device. Such a control may be a rocker switch, a toggle switch, a push-button, a virtual switch on a display screen, or some other user interface. The internationally standardized symbols are intended to communicate their function in a language-independent manner.
The well-known on/off power symbol was the result of the logical evolution in user interface design. Originally, most early power controls consisted of switches that were toggled between two states demarcated by the words On and Off. As technology became more ubiquitous, these English words were replaced with the universal symbols line "|" for "on" and circle "◯" for "off" (typically without serifs) to bypass language barriers. This standard is still used on toggle power switches.
The symbol for the standby button was created by superimposing the symbols "|" and "◯"; however, it is commonly interpreted as the numerals "0" and "1" (binary code); yet, the International Electrotechnical Commission (IEC) holds these symbols as a graphical representation of a line and a circle.
Standby symbol ambiguity
Because the exact meaning of the standby symbol on a given device may be unclear until the control is tried, it has been proposed that a separate sleep symbol, a crescent moon, instead be used to indicate a low power state. Proponents include the California Energy Commission and the Institute of Electrical and Electronics Engineers. Under this proposal, the older standby symbol would be redefined as a generic "power" indication, in cases where the difference between it and the other power symbols would not present a safety concern. This alternative symbolism was published as IEEE standard 1621 on December 8, 2004.
Universal power symbols are described in the International Electrotechnical Commission (IEC) 60417 standard, Graphical symbols for use on equipment, appearing in the 1973 edition of the document (as IEC 417) and informally used earlier.
|IEC 60417-5007, the power-on symbol (line), appearing on a button or one end of a toggle switch indicates that the control places the equipment into a fully powered state. (1 or | means on.)|
|IEC 60417-5008, the power-off symbol (circle) on a button or toggle, indicates that using the control will disconnect power to the device. (0 or ◯ means off.)|
|IEC 60417-5009, the standby symbol (line partially within a broken circle), indicates a sleep mode or low power state. The switch does not fully disconnect the device from its power supply. This may appear on a toggle switch opposite a power on symbol, alone on a pushbutton that places the device into a standby state, or alone on a button that switches between on and standby. Alternatively, under IEEE 1621, this symbol simply means "power".|
|IEC 60417-5010, the power on-off symbol (line within a circle), is used on buttons that switch a device between on and fully off states.|
|A crescent moon, indicating sleep mode, is added by IEEE 1621 as a replacement for the standby symbol.|
Because of widespread use of the power symbol, a campaign was launched to add the set of characters to Unicode. In February 2015, the proposal was accepted by Unicode and the characters were included in Unicode 9.0. The characters are in the "Miscellaneous Technical" block, with code points 23FB-FE, with the exception of U+2B58 ⭘ , which belongs to the "Miscellaneous Symbols and Arrows" block.
- U+23FB ⏻ POWER SYMBOL (IEC 60417-5009 stand-by symbol, IEEE 1621 power symbol)
- U+23FC ⏼ POWER ON-OFF SYMBOL (IEC 60417-5010)
- U+23FD ⏽ POWER ON SYMBOL (IEC 60417-5007)
- U+2B58 ⭘ HEAVY CIRCLE (Used for IEC 60417-5008 power off symbol)
- U+23FE ⏾ POWER SLEEP SYMBOL
In popular culture
The standby symbol, frequently seen on personal computers, is a popular icon among technology enthusiasts. It is often found emblazoned on fashion items including t-shirts and cuff-links. It has also been used in corporate logos, such as for Gateway, Inc. (circa 2002), Staples, Inc. easytech, Exelon, Toggl and others, as record sleeve art (Garbage's "Push It") and even as personal tattoos. In March 2010, the New York City health department announced they would be using it on condom wrappers. The 2012 television series Revolution, set in a dystopian future in which "the power went out", as the opening narration puts it, stylized the second last letter 'o' of its title as the standby symbol. The power symbol was a part of exhibition at MoMA. In the anime Dimension W, Kyouma Mabuchi wears a Happi with the power symbol on his back. In the television series Sense8, the hacktivist character Nomi has a tattoo of the power symbol behind her ear.
The symbol, rotated clockwise by 90 degrees so it looks like a capital G, becomes part of the logo for Channel 5's programme The Gadget Show.
On 15th October 2019, 786 employees of Volkswagen Group United Kingdom Limited formed the world's largest human power symbol at Millbrook Proving Ground. 
- ^ "Off symbol." Symbols.com. STANDS4 LLC, 2022. Web. 7 Feb. 2022. <https://www.symbols.com/symbol/off-symbol>.
- ^ a b c Lawrence Berkeley National Laboratory (December 2002). "The Power Control User Interface Standard (consultant report)" (PDF). California Energy Commission. Archived from the original (PDF) on 2006-10-01. Retrieved 2007-04-26.
- ^ Lawrence Berkeley National Laboratory (December 2002). "Draft Standard for User Interface Elements in Power Control of Electronic Devices Employed in Office/Consumer Environments (consultant report)" (PDF). California Energy Commission. Archived from the original (PDF) on 2006-10-01. Retrieved 2007-04-26.
- ^ "Save Energy at Your PC; Energy Scientists Propose Color-Coding Standard for PC Sleep Mode". American Institute of Physics. 2005-06-01. Archived from the original on 2007-07-06. Retrieved 2007-04-26.
- ^ "Power Management Controls - User Interface Standard - IEEE 1621". IEEE. Archived from the original on 2007-04-21. Retrieved 2007-04-26.
- ^ "IEC 60417 - 5007, "ON" (power)". IEC.
- ^ "IEC 60417 - 5008, "OFF" (power)". IEC.
- ^ "IEC 60417 - 5009, Stand-by". IEC.
- ^ Nordman, Bruce (2005-05-02). "Power Control Made Easy". EE Product News. Archived from the original on February 16, 2009. Retrieved 2007-04-26.
- ^ "IEC 60417 - 5010, "ON"/"OFF" (push-push)". IEC.
- ^ "Unicode Proposal 14009 Power Symbol" (PDF). Unicode. Unicode Consortium. Retrieved Dec 23, 2015.
- ^ West, Andrew (2016-01-10). "What's new in Unicode 9.0?". Archived from the original on 2016-01-07. Retrieved 2016-01-04.
- ^ "Unicode Chart - Miscellaneous Technical - Range: 2300–23F" (PDF). 2016-06-22.
- ^ See for example "Adafruit's iCufflinks pulsate with the power of your Mac love".
- ^ Smith, Robert (2010-03-09). "Official Condom Design: New York's New Sex Symbol". National Public Radio. Retrieved 2011-02-09.
- ^ "MoMA | Is This for Everyone? New Design Acquisitions at MoMA". www.moma.org. Retrieved 2016-07-04.
- ^ "Largest Human Power Symbol". www.guinessworldrecords.com. Retrieved 2022-07-23.
- IEC/ISO Database on Graphical Symbols for Use on Equipment
- IEC Graphical Symbols for Use on Equipment
- ISO/IEC/JTC1 Graphical Symbols for Office Equipment, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory