Which is a commonly accepted value for the lowest voltage that can cause a dangerous electric shock?

The correct choice, which indicates 30 volts, is significant because this voltage level is often recognized as the threshold where electric shock can become a concern for humans. At voltages lower than 30 volts, the sensation may not be strong enough to pose serious health risks under normal conditions. However, at or above 30 volts, especially in the presence of moisture or wet conditions, the likelihood of causing a noticeable and potentially harmful electrical shock increases significantly.

This value is widely supported by safety standards and guidelines set forth by organizations such as the National Electrical Code (NEC) and various safety regulations. They emphasize that even lower voltages, particularly when skin resistance is reduced due to factors like perspiration or wet surfaces, can lead to dangerous situations.

Recognizing 30 volts as the threshold helps in understanding safe operating procedures in electrical and radio environments, emphasizing the need for care and adherence to safety practices when dealing with equipment that operates at or above this voltage level.