Conductors: Materials and Minimum Sizes (310.5), Insulation Types and Wet Locations (Table 310.4(1), 310.10), Identification (Article 200, 310.6), Parallel Conductors (310.10(G)) and Conductor Properties (Chapter 9 Table 8)

Lesson 04-05 covered ampacity. This lesson is the rest of the Conductors sub-bullet — the questions that ask what a conductor may be made of, how small it may be, which insulation goes where, what color each conductor must be, when conductors may be paralleled, and the Chapter 9 Table 8 properties behind voltage-drop problems. Written from the 2026 text.

1. Materials and minimum sizes — 310.2, 310.5, 110.5

• Conductors are copper, aluminum or copper-clad aluminum (CCA); insulated conductors and CCA material are listed (310.2). Where a Code rule does not say, the size given applies to copper (110.5).
• Minimum size (310.5(A), 2026): 16 AWG copper, 14 AWG CCA, 12 AWG aluminum — except as permitted elsewhere (16 AWG copper is a 10 A branch-circuit conductor under 240.4(D) and 210.23; the 14 AWG copper minimum for 15/20 A circuits is unchanged).
• Aluminum: solid 8, 10 and 12 AWG is an AA-8000 series alloy; stranded 8 AWG–1000 kcmil of the RHH/RHW/XHHW/XHHN/XHWN/THW/THHW/THWN/THHN/SE types is AA-8000; CCA has a copper layer of at least 10 percent of the area over an AA-8000 core.
• 8 AWG and larger conductors in raceways shall be stranded (310.5(C)) unless specifically permitted solid.
• Terminations (110.14): terminals identified for the material; no copper–aluminum intermixing unless the device is identified; 60°C column for circuits ≤ 100 A / 14–1 AWG, 75°C over 100 A / larger than 1 AWG, unless the equipment is listed for more.