The normally open (NO) indicator on a distribution box is typically green, indicating that the breaker or switch is de-energized and safe.

Standard Color Conventions

In most electrical distribution systems, green is used to indicate a normally open or de-energized state, while red usually indicates a closed or energized state . This convention is widely applied in utility and industrial settings to signal safety: a green light shows that the circuit is safe to touch or work on, whereas a red light warns that the circuit is live . Yellow or amber is often used for transitional states, such as a breaker in the process of opening or closing .

Variations by Panel Type

• Power Control Panels: ON is often red, OFF is green, and TRIP is yellow .
• Motor Control Panels: Running is green, Stop is red, and Trip is yellow .
• Phase Indication: R phase is red, Y phase is yellow, B phase is blue .

Regional and Standard Differences

While green for open and red for closed is common, some regions or standards may reverse this. For example, IEC-compliant equipment may use green for closed and red for open, whereas ANSI-based systems in the U.S. often follow the opposite . The key is consistency within a facility to avoid confusion and ensure safety.

Practical Implications

When working with distribution boxes, always verify the facility-specific color coding and labeling. Even if green is generally used for normally open, the actual indicator may vary depending on the manufacturer, standard, or local practice . Clear signage and consistent use of colors are critical for safe operation and maintenance.