Quick Hits

Article 390 (Part 2 of 2)
Underfloor Raceways — Splices, Discontinued Outlets, Alignment, Markers & Junction Boxes!

SLIDE 1 — Splices, Taps & Discontinued Outlets (390.56, 390.58)
🔗 SPLICES & TAPS (390.56)
Only allowed in JUNCTION BOXES. Loop wiring (continuous unbroken conductor) does NOT count as a splice or tap.
✅ EXCEPTION: Permitted in trench-type flush raceway with a removable, accessible cover — combined fill can't exceed 75% of the raceway area at that point.
🧹 DISCONTINUED OUTLETS (390.58)
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.

SLIDE 2 — Alignment, Markers & Dead Ends (390.70, 390.71, 390.73)
📏 LAID IN STRAIGHT LINES (390.70)
Raceways must run in a straight line from the center of one junction box to the center of the next — firmly held in place so construction doesn't throw off the alignment.
📍 MARKERS (390.71)
A suitable marker is required at or near each end of every straight run, to locate the last insert.
🚪 DEAD ENDS (390.73)
Dead ends of raceways shall be CLOSED.

SLIDE 3 — Junction Boxes & Inserts (390.74, 390.75)
📦 JUNCTION BOXES (390.74)
Leveled to floor grade, sealed against water/concrete entry. If used with metal raceways → must be metal AND electrically continuous with the raceway.
🔩 INSERTS (390.75)
🔹 Leveled and sealed against concrete entry
🔹 With metal raceways → must be metal, electrically continuous with the raceway
🔹 Fiber raceways: inserts set BEFORE the floor is laid → mechanically secured; inserts set AFTER the floor is laid → screwed into the raceway
🔹 No chips/debris left behind when cutting the raceway wall — tools must be designed to avoid entering the raceway and damaging conductors

SLIDE 4 — Connections to Cabinets & Wall Outlets (390.76) + Final Exam
🔌 CABINET & WALL OUTLET CONNECTIONS
Made using approved fittings or any Chapter 3 wiring method, installed per its own article.

🧠 FINAL EXAM QUESTION FOR ARTICLE 390 (Part 2)
Q: Per 390.56, splices and taps in underfloor raceways shall be made only in what location (barring the trench-type exception)?
A) Header access units
B) Junction boxes
C) Inserts
D) Anywhere accessible
(Drop your final answer 👇)

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