NEC Commercial Electrical Practice Test

For a 4-wire, delta-connected secondary feeder, what color identifies the phase conductor with the higher voltage to ground?

1. Red

2. Blue

3. Yellow

4. Orange

The correct answer is: Orange

In a 4-wire delta-connected secondary system, the color coding of conductors typically follows established industry standards. The phase conductor that carries the higher voltage to ground is generally identified by the color orange. In a delta connection, the configuration means that each phase is connected to the transformer windings in such a way that the line to ground voltage differs from the phase-to-phase voltage. The highest voltage to ground occurs on one of the phase conductors, which is conventionally assigned the color orange for easy identification. This standard helps ensure consistency and safety in electrical installations, minimizing confusion during troubleshooting or maintenance. The other colors, such as red, blue, and yellow, typically signify different phases in a three-phase system, but orange is specifically reserved for the phase that is at a higher ground potential in this context. Thus, knowing this standard is crucial for anyone working with delta-connected systems to properly identify and manage the conductors.