See 300.15 Boxes, Conduit Bodies, or Fittings — Where Required.
A box shall be installed at each outlet and switch point for concealed knob-and-tube wiring.
Fittings and connectors shall be used only with the specific wiring methods for which they are designed and listed.
Where the wiring method is conduit, tubing, Type AC cable, Type MC cable, Type MI cable, nonmetallic-sheathed cable, or other cables, a box or conduit body complying with Article 314 shall be installed at each conductor splice point, outlet point, switch point, junction point, termination point, or pull point, unless otherwise permitted in 300.15(A) through (M).
For a "Boxless Device" See also:
(E) Integral Enclosure. A wiring device with integral enclosure identified for the use, having brackets that securely fasten the device to walls or ceilings of conventional on-site frame construction, for use with nonmetallic-sheathed cable, shall be permitted in lieu of a box or conduit body.
FPN: See 334.30(C); 545.10; 550.15(I), 551.47(E), Exception No. 1; and 552.48(E), Exception No. 1.
Structural components or modules are usually constructed in manufacturing facilities and then transported over the road to a building site for complete assembly of a structure, such as a dwelling unit, motel, or office building.
At the on-site location, approved wiring methods are used to interconnect two or more modules.
Exhibit 545.1 shows a type of nonmetallic-sheathed cable connector permitted for such interconnections.
Exhibit 545.1 A type of nonmetallic-sheathed cable connector used for interconnecting modules in a manufacturing building. (Courtesy of Pass & Seymour/Legrand®)
[This message has been edited by Joe Tedesco (edited 08-12-2004).]