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📱 EPISODE 2 — Article 355 (Part 2 of 2)

Bends, Support, Expansion & Construction — Article 355 Complete!

SLIDE 1 — Bends & Trimming (355.24, 355.28)
🔄 FIELD BENDS NEED IDENTIFIED EQUIPMENT

Same as PVC: field bends MUST use identified bending equipment. Bend radius per Chapter 9, Table 2. Max 360° total bends per run between pull points.

✂️ Trimming: cut ends trimmed INSIDE AND OUTSIDE to remove rough edges.

SLIDE 2 — Securing & Support Table (355.30)
🛠️ SAME SUPPORT TABLE STRUCTURE AS PVC

Secured within 3 ft (900mm) of each termination (unless listed otherwise). Installed as a complete system per 300.20, fastened to allow thermal movement.

📊 Table 355.30(B) — support spacing by size (IDENTICAL numbers to PVC's Table 352.30(B)):
🔹 ½–1 in. → 3 ft
🔹 1¼–2 in. → 5 ft
🔹 2½–3 in. → 6 ft
🔹 3½–5 in. → 7 ft
🔹 6 in. → 8 ft

SLIDE 3 — Expansion Fittings (355.44)
🌡️ RTRC MOVES LESS THAN PVC — BUT STILL MOVES

Expansion fittings required where expected length change is ¼ in. (6mm) or greater in a straight run between securely mounted items.

📊 Per Table 355.44: RTRC's thermal expansion coefficient is LOWER than PVC's — a 100°F change over 100 ft = about 1.80 inches of length change (compare that to PVC's ~4.06 inches for the same conditions). RTRC is noticeably more thermally stable than PVC, but expansion fittings are still required when the threshold is met.

SLIDE 4 — Bushings, Joints, Construction + Final Exam Question
🛡️ BUSHINGS (355.46) & JOINTS (355.48)

Bushings required at enclosure entries (unless the enclosure design provides equivalent protection). ALL joints made by an approved method.

🏗️ CONSTRUCTION (355.100)
Nonmetallic material resistant to moisture/chemical atmospheres. Aboveground use also requires flame retardant, impact/crushing resistant, heat-distortion resistant, low-temp/sunlight resistant. Underground use requires moisture/corrosive resistance and handling-abuse strength; direct burial without concrete encasement also needs continued-loading capability.

🏷️ MARKING (355.120): every 10 ft (3m) per 110.21(A), plus material type. Aboveground markings must be PERMANENT; underground-only markings just need to stay legible until installed.

🎉 That wraps up Article 355 — Reinforced Thermosetting Resin Conduit!

🧠 FINAL EXAM QUESTION FOR ARTICLE 355

Q: Per Table 355.44, RTRC's thermal expansion for a 100°F change over a 100-ft run is approximately how much, compared to PVC's ~4.06 inches under the same conditions?

A) 0.5 inches
B) 1.80 inches
C) 3.60 inches
D) 6.08 inches

(Drop your final answer 👇)

Article 355 = DONE ✅ FOLLOW for more daily quick-hit NEC study notes ⚡ #JoshTheSparky #NEC2026 #ElectricianLife

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