Quick Hits

Article 374 (1 of 1)
Cellular Metal Floor Raceways — Full Article Breakdown!

SLIDE 1 — Scope & Listing (374.1, 374.2, 374.3)
🏗️ WHAT IS A CELLULAR METAL FLOOR RACEWAY?
A listed system of sheet metal formed into shapes that combine to form cells or raceways, built into steel-frame building floor decks — cells run across the building and vary in shape/size based on structural needs.
🔌 Headers connect across the cells to bring conductors into service — separate headers can be run for different systems (power, signaling, communications).
✅ Must be LISTED — governed by ANSI/UL 209.
🚫 Reconditioned raceways AND reconditioned fittings are NOT permitted to be installed (374.3(B)).

SLIDE 2 — Uses Not Permitted + Installation Rules (374.12, 374.18)
⛔ WHERE YOU CAN'T USE THEM (374.12)
1️⃣ Subject to corrosive vapor
2️⃣ Any hazardous (classified) location, unless another article allows it
3️⃣ Commercial garages — except supplying ceiling outlets or extensions below the floor (never above)
🔧 INSTALLATION MUST-HAVES (374.18)
🔹 Connections to cabinets/wall outlets → LFMC, FMC (if not in concrete), RMC, IMC, EMT, or approved fittings (PVC/RTRC/ENT/LFNC allowed if there's a means to terminate an EGC)
🔹 Junction boxes → leveled to floor grade, sealed against water/concrete, metal, electrically continuous with raceway
🔹 Inserts → leveled, sealed, metal, continuous — and NO chips/debris left behind when cutting the cell wall
🔹 Markers → required so cells can be located later

SLIDE 3 — Conductors: Size, Fill & Ampacity (374.20, 374.22, 374.23)
📏 SIZE LIMIT
No conductor larger than 1/0 AWG — unless special permission is granted.
📊 FILL LIMIT
Combined cross-sectional area of conductors/cables ≤ 40% of the interior cross-sectional area of the cell or header.
🌡️ AMPACITY
Adjustment factors from 310.15(C) apply.

SLIDE 4 — Splices, Discontinued Outlets & Final Exam
🔗 SPLICES & TAPS (374.56)
Only allowed in header access units or junction boxes. Loop wiring (continuous unbroken conductor) does NOT count as a splice or tap.
🧹 DISCONTINUED OUTLETS (374.58)
When an outlet is abandoned/removed, the conductors feeding it must be pulled OUT of the raceway — no splices or re-insulated conductors left behind.
🏗️ CONSTRUCTION (374.100)
System must be installed to ensure adequate electrical AND mechanical continuity throughout.

🎉 That's a wrap on Article 374 — Cellular Metal Floor Raceways!

🧠 FINAL EXAM QUESTION FOR ARTICLE 374
Q: Per 374.22, the combined cross-sectional area of all conductors or cables in a cell or header shall not exceed what percentage of the interior cross-sectional area?
A) 25%
B) 30%
C) 40%
D) 53%
(Drop your final answer 👇)

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