ARRL Technician Practice Exam 2025 – Complete Prep Guide

Including a fuse or circuit breaker in series with the AC hot conductor is essential for safety when building and operating equipment powered from 120V AC power circuits. This protective device serves as a crucial safeguard against overcurrent situations, which can arise from short circuits or equipment malfunctions. When excessive current flows through the circuit, the fuse will blow or the circuit breaker will trip, interrupting the power supply and thereby preventing potential fire hazards, equipment damage, or electric shock.

This protective measure is critical for ensuring that the current is limited to safe levels, which not only protects the equipment but also enhances overall safety for the user.

Other options might add functionalities or assist in operation but do not provide that same level of essential protection against electrical faults, making the inclusion of a fuse or circuit breaker in series with the AC hot conductor a non-negotiable component in the design of safe home-built equipment.