What presents the greatest electrical shock hazard when operating a TDR?

The greatest electrical shock hazard when operating a Time Domain Reflectometer (TDR) comes from low-frequency alternating current (AC) voltage on the coaxial cable. This is because low-frequency AC can produce significant currents that are more likely to flow through the human body if a person comes into contact with the exposed conductors or the cable's surface. Additionally, low-frequency AC voltages (typically below 50-60 Hz) are within the range that can induce muscle contractions and interfere with normal heart function, creating a higher risk of serious injury or fatality during exposure.

In contrast, high-frequency AC voltage may lead to different interactions with the body, often resulting in less current flow through the human body due to its tendency to travel along the surface of conductors (the skin effect). Therefore, while high-frequency AC is hazardous, the physiological effects of low-frequency AC are more dangerous. Direct current (DC), while it can also pose risks under certain conditions, does not induce the same physiological responses as AC does. Static electricity, while it can cause shocks, typically does not present a consistent or significant electrocution hazard compared to voltages present in AC systems.