What is an important consideration when working with control transformers according to NEC standards?

When working with control transformers, it is crucial to ensure that one side of the secondary winding is grounded. This practice is foundational in enhancing safety and reducing the risk of electrical shock. Grounding one side of the secondary provides a reference point for the control circuit and helps to stabilize the voltage levels. It also minimizes the potential for dangerous voltage levels that can occur if the secondary is floating (not grounded).

NEC standards emphasize proper grounding to ensure that fault currents have a clear path to earth, which can help trip protective devices and prevent electrical hazards. Grounding can also help in surge protection and in minimizing interference from other electrical equipment, thus ensuring reliable operation of control systems.

The other options do not adhere to the best safety practices or standards set by NEC. While they may have some merit in specific contexts, grounding one side of the secondary is a fundamental requirement that aligns with the safety regulations and operational integrity of control transformers.