Which of the following installations are covered by the NEC®?

The National Electrical Code (NEC®) provides guidelines and standards for a wide range of electrical installations to ensure safety and proper functioning. The NEC is applicable to various types of electrical systems, including residential, commercial, and industrial installations.

Residential electrical systems fall under NEC regulations, as they need to meet specific safety standards for wiring, installations, and equipment used in homes. Similarly, commercial electrical systems are also governed by the NEC, addressing the unique needs and requirements of business environments. Industrial machinery and systems, which often involve more complex electrical needs and greater power demands, must adhere to NEC requirements to ensure safe operation and compliance with local codes.

Therefore, saying "none of the above" is not accurate because the NEC encompasses all these categories of electrical installations. It applies broadly to ensure safety across diverse environments where electrical systems are employed. Understanding this comprehensive coverage helps one appreciate the importance of adhering to NEC standards in all types of electrical work.