What is required to be installed between the transformer and the service panel for a 480-volt, 3-phase service panel?

For a 480-volt, 3-phase service panel, it is essential to install both one grounded conductor and three ungrounded conductors between the transformer and the service panel. This configuration ensures proper electrical grounding and safety.

Grounded conductors, often referred to as neutral conductors, play a crucial role in providing a return path for unbalanced loads and help to stabilize the voltage during operation. This is particularly important in 3-phase systems, where loads may not always be perfectly balanced across the three phases. The grounded conductor also aids in providing protection against overcurrent conditions and facilitates the operation of circuit protection devices for safety.

The ungrounded conductors are the three phases of the 3-phase system, which deliver the necessary power for the operation of various electrical devices and systems. By having three ungrounded conductors, you ensure that there is sufficient current-carrying capacity to meet the energy demands of the installation.

Overall, the combination of one grounded conductor and three ungrounded conductors creates a well-functioning electrical system that adheres to safety and operational requirements, which is why this configuration is essential.