What do red, blue, and black colored buses in an electric panel indicate?

The presence of red, blue, and black colored buses in an electric panel indicates a three-phase supply. In a typical three-phase system, each color corresponds to one of the three phases of the electrical supply. This color-coding facilitates easy identification and connection while also ensuring safety and reducing the risk of confusion when performing electrical work.

Three-phase power is commonly used in industrial and commercial applications because it allows for more efficient transmission of electricity, as well as the ability to power large motors and heavy equipment. Each phase carries an alternating current that peaks at different times, providing a more constant and reliable power supply compared to single-phase systems.

In contrast, a single-phase supply would generally involve only two wires and does not utilize multiple colors for phase indication in the same manner as three-phase systems. Dual-phase and low-voltage supplies also do not align with the three distinct colors representing the phases found in a standard three-phase panel, which strengthens the case for the correct answer being two distinct colors to represent additional phases.