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Does Green mean ON or OFF?

Article#: 00127

Date: 2026-10-09

Author: Radim



Pedestrian traffic light with reversed red and green colors

The answer is not always as simple as it might seem at first glance.

Each of us has a certain idea of what the colors green and red mean, based primarily on our own experience.

Let's start with something we know from everyday life.
A green pedestrian light at a crossing means that we can go. A red one means that we have to stop. We therefore naturally associate green with movement and safety, while red is associated with stopping or danger.

We may have similar expectations when looking at a production machine. If the machine is running normally and producing, a green indication makes sense to us. If it has a fault, has stopped, and requires operator intervention, we would expect red instead.

So far, everything seems simple: green = running, red = stopped or a problem.

But with electrical equipment, we can also encounter the opposite logic. Red can indicate the ON state, while green indicates OFF.

When we look at the colors of start and stop buttons, we quite often see green for switching on and red for switching off.
According to IEC 60204-1, a START / ON pushbutton can be white, grey, black, or green, with white being the preferred color. Red shall not be used.
According to the same standard, a STOP / OFF pushbutton can be black, grey, or white, with black being the preferred color. Red is also permitted, while green shall not be used.

This brings us to an apparently inconsistent and contradictory situation where, for example, when controlling and indicating the state of electrical equipment, we can switch the equipment on with a green pushbutton and then indicate the resulting ON / ENERGIZED state in red.

So what does green actually mean? ON or OFF?
To answer this question, we first need to ask another one: What are we actually indicating?

With a pushbutton, we indicate what we want to do. A green START / ON pushbutton therefore does not describe the current state of the equipment, but the action we want to perform.

An indicator light, on the other hand, provides information about the current state of the equipment. On a production machine, green can therefore mean that the machine is running normally and producing, while red indicates a fault or another problem, meaning that production has stopped.

With electrical equipment, however, the colors can represent the state from the operator's safety perspective: green can indicate a DE-ENERGIZED state, while red can indicate an ENERGIZED state and therefore a potentially hazardous situation.

The meaning of a color therefore depends on what we are actually indicating. And although we have certain established standards and conventions, depending on the context we can end up with an apparent contradiction as to whether green means ON or OFF. It is therefore important to choose the colors of controls and indicators according to the applicable standards and established conventions, and to use them consistently. It is also good practice not to rely on color alone, but to supplement controls and indicators with text or symbols, for example. This helps eliminate possible ambiguity and makes the information easier to interpret for people with color vision deficiency.

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