How high must NMS cable (Romex) be protected when passing through a floor?

The correct requirement for protecting NMS (Non-Metallic Sheathed) cable, commonly known as Romex, when it passes through a floor is 6 inches. This standard is put in place to safeguard the cable from potential physical damage. When cable is run through a floor or along walls, it's crucial to ensure that it is adequately protected, particularly in locations where it could be exposed to impacts or wear.

By requiring that the cable is protected at least 6 inches from the floor, the code helps to mitigate risks associated with accidental contact, which could lead to wear of the sheathing or the conductors inside, increasing the risk of shorts or electrical failures. This height is a compromise between accessibility and safety, ensuring that the cable remains functional while minimizing chances of damage from foot traffic or furniture.