Wiring Methods, Materials, and Installation
Selecting a wiring method
This domain tests whether you can choose and install a wiring method suited to the environment. Know the characteristics of nonmetallic-sheathed cable, armored cable, metal-clad cable, service-entrance cable, and flexible cords, plus the appropriate uses and prohibitions for each. Understand support spacing, securing and protecting cable near boxes, bending radius, and the conditions of use (dry, damp, wet, corrosive, hazardous).
Materials and terminations
Know conductor insulation types and temperature ratings, connector and splice requirements, and why terminations must be made with listed devices. Understand box selection and fill, device mounting heights, and the difference between a fitting and a support. Recognize that materials must be listed for the environment, not merely for the voltage.
Traps in questions
Common distractors include using flexible cord as permanent wiring, burying cable without protection, supporting cable at the wrong interval, mixing conductor insulation ratings in a way that exceeds the lowest rating, and assuming any box works for any fill. Questions also test whether you know that a wiring method permitted in a dry location is not automatically permitted in a wet one.
Worked example
A cable run in a garage must be protected where it is likely to be damaged. Rather than guessing, apply the sequence: identify the environment, check whether the method is permitted there, then confirm support, protection, and termination rules. Rule of thumb: environment first, method second, details third.
Study strategy
Make a comparison table of wiring methods with columns for permitted locations, support spacing, and common prohibitions, then quiz yourself by covering columns.