AFCI (arc fault circuit interrupter) detects dangerous arcing in an electrical circuit. There is normal arcing in electrical circuits. A vacuum motor arcs as it spins. A light switch will arc as it breaks the circuit. AFCI protection distinguishes between normal and dangerous arcing and shuts the circuit off then dangerous arcing is detected. AFCI circuits should be tested for proper operation regularly. AFCI protection is currently required in all sleeping areas and my expand to others areas as the N.E.C. (National Electric Code) has revisions every three years.