The secondary of a transformer delivering 12 volts must have one of its conductors grounded when supplied from a ___.

In this scenario, the requirement for one of the secondary conductors of a transformer delivering 12 volts to be grounded is primarily related to safety standards and electric code. For a transformer to operate safely, particularly in a low-voltage application like this, grounding one side of the secondary circuit is critical to establish a reference point, reduce the risk of electric shock, and enhance the protection against faults.

When supplied from a 277/480-Volt, 3-phase, 4-wire panelboard, this high-voltage system typically employs a grounded neutral conductor. This setup creates a safe and stable reference point for the lower voltage secondary circuit. By grounding one of the conductors on the secondary side, it helps to limit the voltage that a person may come into contact with if a fault occurs. It also aids in the operation of overcurrent protective devices, ensuring that they trip in the case of a ground fault.

This is essential in commercial and industrial applications where grounding is a part of safety measures required by the National Electrical Code (NEC) and other regulatory standards. In contrast, a 2-pole breaker in a 120/208-volt panelboard does not necessitate this specific grounding requirement due to the circuit's configuration and established regulations