Which of the following is a requirement for electrical installations according to the NEC?

Ensuring that all outlets are ground-fault protected aligns with the National Electrical Code (NEC) requirements. Ground-fault protection is crucial in areas where there is a risk of electrical shock, especially in wet or damp environments like kitchens and bathrooms. The NEC mandates that certain receptacles, particularly those in these designated locations, need to have ground-fault circuit interrupters (GFCIs) installed to enhance safety. This protection works by monitoring the electrical current and shutting off the power if a ground fault is detected, effectively reducing the risk of serious injury or electrocution.

While using copper wiring in residential buildings is common due to its conduit properties, the NEC does not dictate that only one type of wiring material can be used. Additionally, the requirement for switch height is flexible and varies based on practical use and building codes, rather than a strict 6 feet. Ungrounded systems are outdated and pose significant safety hazards, which contradicts the NEC's emphasis on safety and reliability in electrical installations. The NEC primarily supports grounded systems and other safety measures, making ground-fault protection a critical requirement for modern electrical installations.