haskindm said:
Perhaps we just need to agree to disagree.
334.15(C) only deals with ceiling joists, there is no mention of studs.
334.17 deals with NM installed "through" framing members and refers you to 300.4.
300.4 explains that conductors should be protected "where subject to physical damage".
300.4(A)(1) explains that "in both EXPOSED and concealed locations" this protection is provided by installing the cable through bored holes at least 1.25 inches from the nearest edge of the wood member. Once this is accomplished, the cable is protected by the "wood members" EVEN IF THEY ARE EXPOSED. To require protection of the 16" of cable running horizontally between the studs, in my opinion, is NOT required by the NEC. Remember that the NEC is permissive. If it does NOT say that NM must be protected by being concealed, then it is not required. I think many are assuming that if NM is visible, it is subject to physical damage. I do not read that in the code... If it is installed in bored holes that meet the requirements of 300.4(A)(1) it is considered protected with or without some other covering.
You addressed 334.15(C), 334.17, + 300.4(A)(1) but not 334.15(A). . Now if you're just dealing with a
ceiling question then 334.15(C) is enough. . But when it comes to the
walls you need to look at 334.15
(A).
"To require protection of the 16" of cable running horizontally between the studs, in my opinion, is NOT required by the NEC."
Is that what 334.15(A) says ?
"If it does NOT say that NM must be protected by being concealed, then it is not required."
I never said concealment was required.
"I think many are assuming that if NM is visible, it is subject to physical damage."
334.15
(B) talks about subject to physical damage. . I'm talking about 334.15
(A). . It's very short, so I'll just post it.
334.15(A)
To Follow Surface. Cable shall closely follow the surface of the building finish or of running boards.
Putting it on running boards will not conceal it and the protection from physical damage is nothing like you would get from conduit. . So forget about "protected by being concealed" and "subject to physical damage". . Just address the wording, "
closely follow the surface".
How does the Romex in the wall in the OP picture "closely follow the surface of the building finish" ?
I've seen garages and outbuildings with exposed midair horizontal runs used as hangers for rakes and shovels many times. . If there was at least a running board, the board would take the bulk of the abuse. . 334.15(A) won't require concealment or full protection from physical damage, but a run "closely follow the surface" will be far less abused.
David