📱 EPISODE 1 — The Annexxed Information Series (Part 1 of 3)
Informative Annexes A–D: The Reference Backbone of the NEC
SLIDE 1 — What Are Informative Annexes? (+ the Reserved Ones)
📚 NOT ENFORCEABLE CODE — BUT ESSENTIAL REFERENCE
Every annex in the NEC carries the same disclaimer: "not a part of the requirements... included for informational purposes only." That means nothing in an Annex is directly enforceable by an AHJ — but they're indispensable tools for calculations, product standards, and understanding how the Code is organized.
🕳️ FUN FACT: Annexes E and J are RESERVED — placeholders with no content, likely held for future topics. If you go looking for them expecting substance, you'll find nothing but a label.
SLIDE 2 — Annex A: Informational References
📋 THE MASTER STANDARDS LIST
Annex A compiles every product safety standard, NFPA document, and other publication referenced throughout the NEC — organized into three tables:
🔹 Table A.1(1) — NFPA standards referenced in the NEC (NFPA 70E, 72, 780, etc.)
🔹 Table A.1(2) — Product safety standards tied to MANDATORY listing requirements (organized by article — e.g., Article 230 alone references dozens of UL standards)
🔹 Table A.1(3) — Standards for equipment WITHOUT a mandatory listing requirement, plus other referenced publications
📌 If you've ever wondered "what UL standard governs THIS specific product," Annex A is where you look it up by article number.
SLIDE 3 — Annex B: Ampacity Calculation Application Info
📊 THE NEHER-MCGRATH METHOD
Annex B provides application data for ampacities calculated under ENGINEERING SUPERVISION — based on the Neher-McGrath conductor ampacity formula (permitted per 310.14(A)(1) and (B)).
Covers:
✅ Typical ampacities for 0–2000V conductors (Tables B.2(1)–B.2(11))
✅ Underground duct bank configurations for 0–5000V
✅ Soil thermal resistivity (Rho) values — average soil = 90, concrete = 55, very dry soil = 120
✅ Burial depth modification rules — deeper burial = derating (6% per additional foot of depth)
✅ Medium-voltage cable shield current correction factors
📌 Even where these calculated ampacities exceed Table 310.16 values, equipment terminal limits per 110.14(C) still apply as the governing constraint.
SLIDE 4 — Annex C: Conduit Fill Tables + Exam Question
🔢 THE SHORTCUT TABLES YOU'VE SEEN ALL SERIES
Annex C provides PRE-CALCULATED maximum conductor counts for same-size, same-insulation conductors — 13 sets of tables (C.1–C.13) corresponding to the 13 conduit/tubing types covered in Chapter 3. Each set splits into general wiring conductors, fixture wires, and compact stranded conductors ("A" tables).
Use it to skip manual fill calculations: pick your conduit type table, find your conductor type/insulation, read off the max count for your trade size.
🧠 TEST YOURSELF
Q: Which two Informative Annexes are currently RESERVED with no content?
A) A and B
B) C and D
C) E and J
D) F and G
(Drop your answer 👇)
FOLLOW — Part 2 covers Annex D's calculation examples and Annexes F, G, H (including Article 80!) ⚡ #JoshTheSparky #NEC2026 #ElectricianLife