Power On/Off: Symbology Explained

Q: All my electronics and gadgets have variations of little circles and lines on the power switch. How do I tell which is actually ON and which is OFF?

Pin it button big

A: To be honest I never knew which direction was ON or OFF until this question was recently asked. I simply flipped the switch in the other direction without much thought. Whether it’s a toggle or a single push button, the little symbols on the buttons actually have meaning behind them that visually define what that button is supposed to do. A quick peek at Wikipedia (and double checked through the listed sources), The International Electrotechnical Commission (IEC) is the group behind the standard that provides the following definitions:

Pin it button big

IEC 5007, the power on (line) symbol, appearing on a button or one end of a toggle switch indicates that the control places the equipment into a fully powered state. It comes from the binary system (1 or | means on)

Pin it button big

IEC 5008, the power off (circle) symbol on a button or toggle, indicates that using the control will disconnect power to the device. It comes from the binary system (0 means off)

Pin it button big

IEC 5010, the power on-off symbol (line within a circle), is used on buttons that switch a device between on and fully off states.
IEC 5009, the standby symbol (line partially within a broken circle), indicates a sleep mode or low power state.

Pin it button big

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.

Pin it button big

A crescent moon, indicating sleep, is added by IEEE 1621 as a replacement for the standby symbol.

Now we know the difference between all the buttons and symbols other than just ON or OFF.

(Images: Flickr member F Delventhal licensed for use under Creative Commons)

2 Comments