What is the purpose of using non-metallic sheathed cable (NM)?

• A. To safely convey electrical current while providing a level of protection against physical damage.
• B. To reduce electrical resistance in wiring.
• C. To protect against electromagnetic interference.
• D. To provide flexibility in high-temperature environments.

Answer: (A)

The purpose of using non-metallic sheathed cable (NM) is primarily to safely convey electrical current while offering a level of protection against physical damage. NM cable, commonly known as Romex, is constructed with a non-metallic sheath that encases insulated conductors. This design provides several advantages, including protection from incidental physical damage that might occur in residential environments where the wiring is installed.

Additionally, NM cable is lightweight and easier to handle than its metallic counterparts, making it a popular choice for residential applications. The non-metallic sheath also helps to reduce the risk of electrical hazards, as it is less likely to corrode or degrade over time compared to metal sheathing. This characteristic supports the overall safety and reliability of electrical installations in homes.

While reducing electrical resistance and protection against electromagnetic interference are important considerations for electrical systems, they are not the primary functions of NM cable. Likewise, providing flexibility in high-temperature environments typically pertains to specialty cables designed for specific scenarios, rather than the standard NM cable used in most residential wiring.