First, came the news that “wi-fi” doesn’t actually mean anything. Then, I learned that “USB” stands for “Universal Serial Bus”, and it says a lot about how information can be moved from and into your computer.
But I’ll admit I hadn’t really thought about the power symbol until I learned its secret reference.
Yep – the classic broken circle-and-line design actually used to mean standby, and it’s described as a “brilliant result of evolving technology” by the Museum of Modern Art (MoMA).
Why do we use symbols for power instead of “on and off”?
There are different types of power symbols, so let’s start by explaining which one we mean here.
Some “on/off” signs use a circle (for off) and a straight line (for on). These shapes are listed as numbers 60417-5008 and 60417-5007 in the International Electrotechnical Commission (IEC)’s guide for universal symbols, respectively.
Justus Menke via Unsplash
Another combines the universal sign for on and off – a line and a circle – in an unbroken ring that contains a smaller vertical dash in its middle (IEC 60417-5010).
But the one we’re talking about (IEC 60417-5009) originally stood for “stand-by” and was invented in 1973. It suggested a device was in “sleep mode” or using very little power, but was not completely disconnected.
However, the MoMA said that 30 years later, “an international committee of scientists and engineers recommended that this combined symbol should stand for its more commonly accepted understanding: power”.
It’s especially associated with power switches which offer a “soft-off” option, or for which the distinction between “soft off” and “hard off” isn’t that important.
Dima Shishkov via unsplash
Before all of these symbols were created, many power buttons just had written options for “on” or “off”.
However, a universal symbol has many benefits over written instructions – even seemingly simple ones like these. It works across languages, and it means you don’t have to work out the context of the words (you might be able to turn some things “on” or “off” in a machine without actually taking away or turning on its power, for instance). Universal electronic signs seem to reduce errors.
What does the power symbol mean?
The reason we use circles (off) and straight lines (on) to indicate power, regardless of how they’re arranged, is because they symbolise “a closed electrical circuit (device on) and an open circuit (device off)”, MoMA explained.
The one we use most often – IEC 60417-5009, or the ex-standby button – is just a particularly common combination of the two.
However, this poses a bit of a problem, according to experts. Now that everyone thinks this symbol means power, how are we meant to know when something’s on standby?
A 2002 report previously suggested using a crescent moon symbol to suggest a device is “asleep”.
After that report, the symbol was accepted and added to the Institute of Electrical and Electronics Engineers (IEEE) under IEEE Standard 1621 in 2004.
