Explain ground fault protection requirements and methods for electrical systems.

Ground fault protection detects current flowing to ground (indicating insulation failure or contact with grounded objects) and disconnects the circuit before fire or injury occurs. NEC requires ground fault protection for services over 1000A at 480Y/277V. Methods include zero-sequence CT sensing ground current, residual current monitoring in 3-phase systems, and GFCI devices for personnel protection. Healthcare facilities have special requirements to prevent power interruption during procedures.