At what height is non-metallic sheathed cable considered protected from physical damage in USA?

Answer 1

When run exposed on walls in unfinished basements the 2005 NEC clarifies that the entire length of NM cable run exposed below the "framing members" above that wall, must be protected from physical damage. Also, the end of the protecting sleeve must have a non-metalic bushing. The NEC does not specify a measurement, but it refers to "in exposed work". Everything below the beam is "exposed". The workbook also shows sample sketches that show the protecting sleeve going all the way up to the ceiling beam. If running the cables on the underside of the framing members (beams) physical protection is not required. But smaller size cables require a running board between the cable and the beams. reference 2005 NEC 334.15C

Answer 2

Non-metallic sheathed cable in the USA is typically considered protected from physical damage when it is installed at a height of 8 feet or more above the finished floor level. This guideline is meant to prevent accidental damage to the cable from activities such as drilling or nailing into walls.