Q:

Are nail plates required on the exterior wall side of the wall studs?

My steel building has 2"x6" wall studs and 2"x4" exterior purlins. The steel siding is attached with screws to the purlins. I've run my wiring behind the studs and attached it to the top of the purlins. Thus the wiring lays on the purlins behind the 2"x 6" studs. The inspector stopped by and informed me that nail plates are required where less than 1 1/4" of wood is between the wall face and the wiring. Since there is actually 5 1/2" from the inside wall face to the wiring, he's now referring to the exterior wall. I thought the purpose of nail plates was for protection from nails or screws being inserted from the inside of the building. Why would anyone be needing protection from nails or screws being inserted from the outside wall? I didn't argue but I don't think he's correct. I guess I'm wondering if he NEC defines the wall face where nail plates are required? I'd be surprised if the face wall refers to the outside exterior side of the building wall. Thanks

A:

The code does not differentiate which face of the stud. It simply says: 

"300.4(A)(1)Bored Holes
In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed through bored holes in joists, rafters, or wood members, holes shall be bored so that the edge of the hole is not less than 32 mm (1¼ in.) from the nearest edge of the wood member. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by screws or nails by a steel plate(s) or bushing(s), at least 1.6 mm (1/16 in.) thick, and of appropriate length and width installed to cover the area of the wiring."

