IDC, NAC, and SLC circuit types; Class A, B, and X wiring topologies; the formal Style designations underneath them; and pathway survivability — the full circuit-theory foundation the rest of the program builds on.
Two of this module's core comparisons — NAC vs. SLC, and Class A vs. Class B — already have their own free, diagram-illustrated Concept Explainers in this studio, linked just below. Read (or re-read) both before continuing; this module assumes that ground is covered and deliberately doesn't repeat it.
What this module covers instead is the ground those two explainers don't: IDC — the older conventional circuit type Module 1 named but never explained — and how its end-of-line resistor supervision actually works electrically; Class X, a third wiring class beyond A and B that most training skips entirely; NFPA 72's formal numbered and lettered Style designations that sit underneath the plain-language "Class A/B" names you already know; how circuit type, class, and style are three independent, stackable classifications rather than one label; and a genuinely deeper pass on pathway survivability levels 0–3 than Module 6's brief introduction — the specific cable and conduit protection methods, and the acceptance testing that has to confirm they were actually installed, not just specified.