Which transformer-supplied system must be grounded if the supply voltage exceeds 150V?

• A. Systems above 150V
• B. Systems less than 50V
• C. Systems exactly at 150V
• D. Systems only in commercial buildings

Answer: (B)

The correct understanding of grounding requirements relates to the supply voltage levels and safety measures. When supply voltages exceed 150V, it is critical to ensure that such systems are grounded to protect both the equipment and personnel from electrical faults and to maintain system stability.

In systems with supply voltages above 150V, grounding provides a path for electrical faults to safely dissipate, reducing the risk of electric shock and fire hazards. This grounding requirement is vital because it helps to ensure that protective devices, like circuit breakers or fuses, operate effectively in the event of a fault.

Systems categorized as below 50V generally have much lower risks and may not necessitate strict grounding measures to the same extent as higher voltage systems. However, when voltages exceed the designated threshold, like 150V, grounding becomes a mandatory safety procedure to mitigate potential hazards associated with higher voltage exposure.

The other choices focus on different voltage ranges or contexts that do not include critical safety protocols for systems above 150V, which highlights why this knowledge of grounding requirements is essential in electrical safety practices.