What is a disadvantage of non-metallic sheathed cable?

Non-metallic sheathed cable, commonly used in residential wiring, has several advantages, but one notable disadvantage is its susceptibility to mechanical damage, which aligns with the correct answer. This type of cable typically features a plastic sheath that provides some level of protection; however, it is not as robust as metallic sheathing. As a result, non-metallic sheathed cable can be more easily damaged by impacts or abrasions, leading to potential exposure of the wires inside, which poses both safety and performance risks.

The other options highlight characteristics that are less relevant to the fundamental weaknesses of non-metallic sheathed cable. While it is true that these cables may not come with a grounding wire (which can be an issue) in certain configurations, many types do include a grounding conductor. Hardness to strip is not generally regarded as a major drawback; qualified electricians typically find stripping these cables manageable with the right tools. Lastly, while non-metallic sheathed cable does have a degree of vulnerability to atmospheric conditions, it is designed for indoor applications where such exposure is minimal, making it far less relevant to the consideration of mechanical breakage. Therefore, the primary concern remains the potential for physical damage, validating the selection of this answer.