Quick Hits

Article 378 (Part 2 of 2)
Nonmetallic Wireways — Insulated Conductors, Support, Expansion, Splices & Marking!

SLIDE 1 — Insulated Conductors: Deflection & Pull Boxes (378.23)
📐 DEFLECTED CONDUCTORS (378.23(A))
Where conductors are deflected (at ends, where raceways/cables enter/leave, or the wireway direction changes more than 30°) → one-wire-per-terminal dimensions from Table 312.9(A) apply.
🎣 USED AS A PULL BOX (378.23(B))
For insulated conductors 4 AWG or larger pulled through: distance between entries enclosing the same conductor must meet 314.28(A)(1) for straight pulls / (A)(2) for angle pulls — use the minimum trade size raceway equivalent when transposing cable size.
💡 Same logic as conduits entering boxes — makes sure there's enough room to bend conductors without damaging insulation.

SLIDE 2 — Securing & Supporting (378.30)
📏 HORIZONTAL SUPPORT (378.30(A))
Supported at intervals not exceeding 900mm (3 ft), and at each end/joint — unless listed for other intervals. Distance between supports shall never exceed 3m (10 ft).
📏 VERTICAL SUPPORT (378.30(B))
Securely supported at intervals not exceeding 1.2m (4 ft) — unless listed otherwise — with NO more than one joint between supports. Adjoining sections must be securely fastened together for a rigid joint.
📌 Notice: nonmetallic support intervals are TIGHTER than metal wireway (376) — 3ft/4ft here vs 5ft/15ft for metal.

SLIDE 3 — Expansion Fittings & Splices/Taps (378.44, 378.56)
🌡️ EXPANSION FITTINGS (378.44)
Required to compensate for thermal expansion/contraction where the calculated length change (per Table 352.44) is expected to be 6mm (0.25 in.) or greater in a straight run.
🔗 SPLICES & TAPS (378.56)
Permitted within a nonmetallic wireway if accessible — conductors, splices, and taps combined shall not fill more than 75% of the wireway's area at that point.

SLIDE 4 — Dead Ends, Extensions & Marking (378.58, 378.70, 378.120) + Final Exam
🚪 DEAD ENDS (378.58)
Must be closed using LISTED fittings.
🔌 EXTENSIONS (378.70)
Made with cord pendants or any Chapter 3 wiring method — a separate EGC must be installed in (or an EGC connection made to) the extension's wiring method.
🏷️ MARKING (378.120)
Must show manufacturer's name/trademark AND interior cross-sectional area in square inches, visible after installation. Limited smoke marking permitted where applicable.

🧠 FINAL EXAM QUESTION FOR ARTICLE 378 (Part 2)
Q: Per 378.44, expansion fittings are required where the calculated length change in a straight run is expected to be at least what?
A) 3mm (0.125 in.)
B) 6mm (0.25 in.)
C) 12mm (0.5 in.)
D) 25mm (1 in.)
(Drop your final answer 👇)

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