Sometime I started (slow pace) the rewiring process of a large mansonry house. Overall I intend to use EMT conduit inside walls, and in the attic mostly bx/mc conduit. Will mostly use 12G THNN and sometimes I will use romex (and will derate the conduit whenever required: 100% filling rate) The house has a small basement (which is a breeze to do for what there is no ton of insulation there) and I plan on using mostly EMT, THNN, and sporadically nm-b.
I understand that romex is required to be affixed/clamped 12" from a box and also in the box's knockout. I have a situation whereby the romex travels a very short distance (about 4 feet) inside a partial wall which then makes it very difficult to clamp the wire at the box end or inside the wall cavity. The pic below depicts the situation:
The box below will contain a light switch and a dual receptacle, and the romex come from inside the wood joist and unless I drill a large bore there (or a special fitting exist) I don't see how to clamp the wire to the box itself:
The romex travels about 3 or 4 feet to the junction box (left of the switch box facing) inside the narrow wall cavity, thus making it difficult to clamp within the wall too.
So, I was wondering whether or not I could use the exception present on NEC 334.30(B) [see below exception] and thus do not use clamp at the box, at 12" of the box, and within the short section inside the narrow wall cavity.
334.30 Securing and Supporting Nonmetallic-sheathed cable shall be supported and secured by staples, cable ties, straps, hangers, or similar ﬁttings designed and installed so as not to damage the cable, at intervals not exceeding 1.4 m (4 1⁄2 ft) and within 300 mm (12 in.) of every outlet box. junction box, cabinet, or ﬁtting. Flat cables shall not be stapled on edge. Sections of cable protected from physical damage by raceway shall not be required to be secured within the raceway. (A) Horizontal Runs Through Holes and Notches. In other than vertical runs, cables installed in accordance with 300.4 shall be considered to be supported and secured where such support does not exceed 1.4-m (4 1⁄2-ft) intervals and the nonmetallic-sheathed cable is securely fastened in place by an approved means within 300 mm (12 in.) of each box, cabinet, conduit body, or other nonmetallicsheathed cable termination. FPN: See 314.17(C) for support where nonmetallic boxes are used (B) Unsupported Cables. Nonmetallic-sheathed cable shall be permitted to be unsupported where the cable: (1) Is ﬁshed between access points through concealed spaces in ﬁnished buildings or structures and supporting is impracticable. (2) Is not more than 1.4 m (4 1 ⁄2 ft) from the last point of cable support to the point of connection to a luminaire or other piece of electrical equipment and the cable and point of connection are within an accessible ceiling