Quick Hits

EPISODE 8 — Temperature Extremes, Other Systems and Wet Raceways Above Grade 1kva (305.17, 305.18, 305.19)

Slide 1 — Hook "Today: condensation prevention, why electrical raceways stay electrical-only, and wet raceways above grade."

Slide 2 — 305.17 Raceways exposed to different temperatures

• Where parts of a raceway/sleeve see different temperatures and condensation is a known issue (cold storage, interior-to-exterior transitions): seal it to stop warm air circulating to the colder section, using sealants identified for the components involved — no explosionproof seal needed.

• Expansion/expansion-deflection/deflection fittings are required wherever needed to handle thermal expansion, deflection, and contraction.

Slide 3 — 305.18 & 305.19

• 305.18: raceways/cable trays with electrical conductors CANNOT also contain pipes/tubes for steam, water, air, gas, drainage, or any non-electrical service — same rule as 300.10.

• 305.19: raceways in wet locations ABOVE grade have their interior automatically classified as wet — conductors/cables must be either moisture-impervious metal-sheathed OR listed for wet-location use.

Slide 4 — Quiz + CTA Q: "Can a medium-voltage raceway share space with a water pipe?" A) Yes, if properly sealed B) No — raceways can't contain pipes for non-electrical services C) Only underground D) Only if the pipe is nonmetallic

✅ Answer: B — 305.18 prohibits mixing electrical raceways with non-electrical service pipes, same as the low-voltage rule.

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