GFCI adapter plug features a NEMA 5-15P plug and NEMA 5-15R receptacle, which could convert any standard indoor electrical outlet into a ground fault (GFCI) protected outlet. When the leakage current in the circuit or load equipment or the ground neutral fault reaches to the 4~6mA, the GFCI plug can break the circuit automatically within 0.025 Seconds (25ms). The GFCI outlet automatically conducts a self-test (auto-monitor) every 5 seconds to ensure the GFCI is continually working to protect people from electrocution, which exceeds the UL standards of self-test frequency of 3-hours. These are the ideal products to provide safety protection for electrical devices without GFCI, shall be easily connected to the power cord of the electrical devices, and are widely applicable to cleaning machines, cutting machines, vacuum cleaners, water pumps, household appliances, outdoor power tools and other portable electrical equipments.