Final answer:
NEC requires safeguards for electrically conductive materials that may become energized, employing insulation and grounding to prevent shock and thermal hazards. Plastic insulation on live/hot wires and the three-wire system with proper grounding are crucial to these safety measures.
Step-by-step explanation:
The question pertains to the Electrical Safety measures mandated by the National Electrical Code (NEC), particularly those that require any electrically conductive materials that are likely to become energized to be safeguarded to prevent both thermal and shock hazards.
The NEC stipulates the use of insulation, grounding, and other safety systems to ensure electrical safety. Plastic insulation on live/hot wires is utilized to prevent electrical shock, which happens when the body becomes a pathway for current flow, particularly when it provides a direct path to the ground. Insulation acts as a barrier and provides resistance, thus helping to prevent such hazards. Additionally, the use of a three-wire system with live/hot, neutral, and earth/ground wires, along with grounding the neutral wire and the case of the appliance, further guards against both thermal and shock hazards. These safety systems, including circuit breakers and fuses, are designed to interrupt excessive currents to prevent overloading and potential fires, thereby addressing thermal hazards.