GFCI (Ground Fault Circuit Interrupter) detects current leaking to ground — typically from water contact — and trips in 1/40th of a second to prevent electrocution. Required in bathrooms, kitchens within 6 feet of a sink, garages, outdoors, and other wet locations. AFCI (Arc Fault Circuit Interrupter) detects arcing faults in wiring — abnormal electrical discharges that can ignite fires — and trips the circuit before a fire starts. The 2020 NEC (Utah’s current adopted code) requires AFCI protection on virtually all 15- and 20-amp 120V branch circuits in dwelling units, including bedrooms, living areas, hallways, and kitchens. Some locations require both GFCI and AFCI protection simultaneously via dual-function breakers.