What Do Power Button Symbols Mean?

We often ignore the simpler things in life, just like the power buttons on our daily-use technology. Have you ever thought why the power buttons on all gadgets, technologies, and items are the same, even though they are from different manufacturers?

3 power buttons
Power buttons with different symbols

If you have, then you have come to the right place. Let us tell you the story behind the power button symbol, and why it is what it is.

Why is a symbol necessary for power buttons?

Well, for one reason, it’s obvious that it was necessary to mark the power buttons so that a person will know what function that particular button will do. It could be dangerous when a person does not know what the function of the button is, and they could accidentally power it on or off that could result in someone getting injured.

There was a need to develop a universal sign that could be understood by everyone around the world. It would have been much simpler to write On/Off on the buttons, but not everyone around the world understands English. It could also get a little confusing, and a person could have difficulty reading the signs, even if they knew English.

on off inverted

To avoid any mishaps, an international committee known as the International Electrotechnical Commission (IEC) was handed the responsibility to create a symbol that could be understood by everyone around the world. In other words, a new “standard” was to be implemented, which was to be followed by everyone.

How the I and O power button symbols were created

The IEC decided that the symbols to be used for power on and power off would be “I” and “O,” respectively. The “I” represents the binary 1, meaning on, whereas the “O” represents the binary 0, meaning off.

The binary number system was understood by almost everyone worldwide and meant the same in every language. Moreover, it would not be confusing for the people even if the button was turned upside-down or rotated any-which-way.

This factor was important to consider as the light switches in the US are in the up-position for on and down-position for off. In contrast, many other parts of the world have adopted the opposite, i.e., up-position for off and the down-position for on. Using the “I” and “O” symbols, it would no longer be a problem for the individuals to know which way is on and which way is off, regardless of which part of the Earth you belong to.

Understanding the different power button symbols

Even though the IEC had agreed to use certain symbols, then why are there variations in it? This is because they had standardized different symbols for different types of buttons. Let us dig into them a little deeper.

IEC 60417-5007 – Fully powered on state

This standard is used for the power-on symbol, which is a simple “I.” This is to mark a button or a toggle switch (rocker switch) to indicate that it is in a fully powered state.

fully powered state
IEC 5007 & IEC 5008 rocker switch

IEC 60417-5008 – Complete power off state

This standard is used for the power-off symbol, which is a simple “O.” Using this control will mark the device as “off,” and there will be no power. This, too, can be found on rocker switches.

off 1
IEC 5007 & IEC 5008 rocker switch

IEC 60417-5010 – Temporary On state

This symbol is usually found on the buttons used to turn off a device and switch it on by toggling them. A simple line within a circle depicts the symbol.

When the button is pushed, the device is powered on and when the button is released, the device powers off.

IEC 5010 button symbol

IEC 60417-5009 – Not fully disconnected state

This one is the most common symbol used all over the world. It is depicted by a broken circle with a line in between the two broken ends. Initially, this symbol was used for the “sleep” state, where the power is not fully cut off to the device and is in a low power state.

partial cirlce
IEC 5009 button symbol

However, later the Institute of Electrical and Electronics Engineers (IEEE) intervened and said that this symbol is to be used for single buttons to toggle between the off state and the on state of a device. They also introduced a new symbol to illustrate the “sleep” state.

Crescent moon

The IEEE then introduced a new shape for the “sleep” state, the crescent moon. Using this control would put the device in a low-powered state. However, this symbol did not catch on much with the general public.

Sleep-state symbol: Crescent moon

Closing words

With these standards set, it is now easier for everyone to understand which way the button is on and which is off. However, all computers now come with a power button with an IEC 60417-5009 standard. Pressing the button once for a short period of time, if the device is on, will put it to sleep, and a long-press will shut it down.

This is because the two international bodies agreed that the same symbol might be used for both purposes, and that is why the same button can be used to perform the “power on/off” function and put the device to “sleep.”

Subhan Zafar

Subhan holds a degree in Electrical Engineering and has completed several system and network certifications including Huwaei, Cisco and Microsoft certs. He mostly researches and writes about the Windows world.

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