Final answer:
GFCI and AFCI devices are critical for protecting against electric shock and fires by detecting leakage currents and arcing conditions, respectively, especially in outdoor areas prone to moisture.
Step-by-step explanation:
Ground Fault Circuit Interrupter (GFCI) and Arc Fault Circuit Interrupter (AFCI) are safety devices designed to protect against electric shock and fire hazards. GFCIs detect imbalances between the live/hot and neutral wires. Such imbalances, often due to leakage currents, can occur when current returns to the voltage source through unintended paths. If the leakage current exceeds 5 milliamperes, the GFCI will trip to interrupt the circuit, because this is the threshold for a safe shock. GFCIs are essential for outdoor receptacles and lighting, as these areas are prone to ground faults due to moisture. Likewise, AFCIs protect against fires by detecting arcing conditions within a circuit, which are otherwise not detectable by standard circuit breakers or fuses.