Low Voltage Cabling and Wiring Methods
This domain tests whether you can choose and install a wiring method that matches the environment and the circuit class. Know the common raceways and methods: EMT, IMC, rigid PVC, FMC, LFMC, surface raceway, cable tray, and J-hook or bridle-ring support; know which are permitted in plenums, risers, wet locations, and hazardous areas. Understand cable jacket and insulation ratings-CM, CMR, CMP, and the outdoor and direct-burial variants-and why CMP is required in air-handling spaces unless a raceway method satisfies the exception. Support spacing, bend radius, and fill are frequent question targets: fiber and copper have different minimum bend radii, and conduit fill follows Chapter 9 tables, not guesswork.
Traps include using riser-rated cable in a plenum, exceeding 25 lb of pulling tension on small copper, and mixing Class 2 with line voltage in a box without a barrier. Also watch separation from power: parallel runs need spacing or a barrier, and crossings should be at right angles.
Rule of thumb: pull to no more than the manufacturer's tension limit, and never exceed the bend radius; when in doubt, use the larger radius.
Worked example: a 100 ft pull around two 90-degree bends. Compute jam ratio and fill first, add a pull point if fill exceeds 40 percent for three or more conductors, and use lubricant rated for the jacket.