When NM exposed cable passes through a floor, which wiring method is permitted for protection?

When NM (non-metallic) exposed cable passes through a floor, the permitted wiring method for protection is RTRC-XW (Residential Wiring, Underground Rated Cables, with Water Resistant Jackets). This method is designed specifically for instances where NM cables need to be protected, particularly in areas subject to moisture or other potential hazards. RTRC-XW cables are built to withstand harsher conditions than standard NM cables, making them suitable for use in scenarios where exposure to elements may compromise the integrity of the wiring.

Using RTRC-XW ensures that the wiring maintains compliance with safety standards and reduces the risk of electrical hazards related to cable damage. It also provides necessary insulation and protection against moisture, making it especially useful when cables cross floor areas that may be prone to spills or leaks.

The other methods may only be partially suited for protection in specific contexts or may not provide the same level of moisture resistance or suitability for exposed applications. Thus, RTRC-XW is the most applicable and safe choice in this situation.