Indicating Lights

Two ways to look at it:

1. There are no standards.
2. There are too many standards so nobody follows them.

In some industries, especially large ones with their own standards such as the Automotive industry:

• Red = Running / Energized / Operating / Dangerous conditions
• Green = Ready / Safe / Standby
• White = Power Available, usually Control Power Available
• Amber / Yellow = Alarm / Alert / Fault

In other industries, food production for example where there are a lot of untrained workers, they use the "Traffic Light" scheme because their unsophisticated workers can relate to it:

• Red = "Stopped" / Off / Safe
• Green = "Go" / Running / Energized