What transformer secondaries are permitted or required to be grounded?

In electrical installations, grounding transformer secondaries is important for both safety and system performance. The selection of which transformer secondaries can or must be grounded often depends on the specific type and use of the transformer.

The choice indicating that the 480 to 120 VAC for motor control is a required option is valid because secondary windings in control transformers supporting motors, especially if they are intended to power control circuits, usually need to be grounded to ensure safety and operational stability. Grounding these secondaries minimizes the risk of electrical shock and helps to protect equipment from power surges or failures.

The other transformers specified, especially in options involving lower voltages like the 120 to 12-volt AC transformation and the 480 to 120/240-VAC configurations, may not necessarily require grounding, based on their specified applications. Additionally, while grounding practices can vary based on local codes and regulations, grounding for high-voltage to low-voltage transformation primarily applies where high current might flow, such as in motor control systems.

In summary, the importance of grounding the 480 to 120 VAC for motor control arises from the need to mitigate risks associated with electrical faults, ensure proper operation, and comply with safety standards, solidifying the understanding of proper grounding in