National Electrical Installation Standards

Standards as High as Your Own

Monday, July 29, 2002


Please discuss the protection of nonmetallic sheathed cable (Type NM) in exposed situations. Section 336 indicates the methods for installing NM cable in exposed conditions. In the jurisdiction where I work, NM cable in garages, even if fastened and secured to the framing, is required to be covered or protected by either sheetrock or plywood to a height of 7 ft above the floor of the garage. At more than 7ft above the floor, the NM cable is not required to be covered or protected. Please explain if these requirements are an accurate interpretation and enforcement of the Code. (For the purposes of this discussion, let's assume this is a detached garage where there is no requirement or concern for fire separation of occupancies or uses; and there is no need for fire-protection of framing members.) My reading of the code would allow NM cable to be exposed ("uncovered" by wall finish) if it is properly secured to the sides of studs (a minimum of 1-1/4" from the face of the studs), and if the cable closely follows the framing. Cable passing horizontally from stud to stud, however, would not be allowed since the cable in this case does not follow the framing. The inspectors in this jurisdiction, though, interpret the code as requiring that any NM cable in the walls of a garage (even if closely following the framing) be protected or covered -- up to 7 ft above the floor. My contention is this: if NM cable is properly secured to the framing, and if it closely follows the framing, then it can be exposed, even if it is in the stud bays of the walls, and even if it is lower than 7 ft from the floor. The local inspectors enforce the NEC in such a way that no NM cable can even be "visible" in a wall until it is 7 ft above the floor. I think the inspectors' interpretation is incorrect. Also, I think that there is confusion over the "7-ft rule." I think the issue is being confused with the requirement that exposed cable in an attic shall be protected by guard strips if within 7 ft of the floor joists. I think the application of a "7 ft above the floor of the garage rule" is incorrect. The Code clearly says that NM can be used in exposed locations. The inspectors seem to disallow this installation. Please discuss and clarify.


The answer I am going to give conforms to the 2002 NEC. However, installers must understand that there may be local electrical code requirements in their areas that supersede or supplement the Code requirements. NEC 334.15 (336-6 1999) covers “Exposed Work”. If I understand you correctly, you are installing Type NM cable in a residential garage constructed of wood studs with no wall covering, such as sheetrock. You are properly securing the cable to the wood framing in accordance with NEC 300.4(A) and 334.30. (Please note that there is no restriction prohibiting the cable from “passing horizontally from stud to stud” as long as the requirements of 300.4(A) are followed.) The 7 ft-rule for attics is not an issue here and I’m sure the AHJ is aware of that. NEC 334.15(B) requires “exposed work” to be protected from physical damage by some “means." If you were to install the cable in sleeves made from conduit, electrical metallic tubing, Schedule 80 PVC rigid non-metallic conduit, guard strips, listed surface metal or nonmetallic raceway, or other means you would be in compliance with the NEC. The AHJ, by requiring sheetrock or plywood, is not making you provide protection from physical damage but rather converting this installation to a concealed one where physical protection is not required. The AHJ apparently feels that a height requirement of 7 feet is sufficient for physical protection, and that exposed cable above that height does not require such physical protection. Using 7 ft, as required in NEC 320.23 (Armored Cable), referenced by NEC 334.23, as a guideline seems perfectly logical.

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