Certified Biomedical Equipment Technician (CBET) Practice Exam

A ground-fault circuit interrupter (GFCI) is designed to prevent electrical shock by detecting the imbalance of electrical current between the "hot" and "neutral" wires. If there is a ground fault, such as when a person accidentally touches a live wire, the current flowing through the "hot" conductor does not return through the "neutral" conductor, resulting in a difference in current. The GFCI is designed to open the circuit when this difference reaches a specific threshold.

The correct answer indicates that a GFCI typically trips at a difference of 6 mA (milliamperes). This level of sensitivity is sufficient to provide protection against electrical shock, as it is below the threshold that can cause a life-threatening condition in humans. Specifically, currents above this level can lead to serious injury or fatality, thus the GFCI monitoring multiple circuits ensures a quick response to such hazardous conditions.

The other options do not align with the widely accepted standards for ground-fault protection: microamp values are too low for practical use in household or similar settings, while a threshold too high could compromise safety. Thus, recognizing the appropriate trip level of 6 mA is crucial for understanding the functionality and safety provided by GFCIs