Quick Hits

Episode 2: Low-Voltage Installations: Physical Protection, Clearances & Insulation (470.10 – 470.12)

SLIDE 1 (HOOK / COVER)

⚡ NEC Quick Hit: Low-Voltage Resistors & Reactors (Part 2) ⚡

Physical protection rules, the 12-inch thermal barrier requirement, and 90°C conductor insulation ratings—let's check Sections 470.10 through 470.12! 👇

SLIDE 2 (LOCATION & SPACE SEPARATION)

Guarding Against Heat and Damage (1000V or Less):

• Physical Damage: Resistors and reactors must never be placed where they are exposed to physical damage.

• Thermal Barriers: A thermal barrier is required if the space between resistors/reactors and any combustible material is less than 305 mm (12 in.).

SLIDE 3 (CONDUCTOR INSULATION)

Wiring Resistance Elements:

• 90°C Minimum Rating: Insulated conductors used for connections between resistance elements and controllers must be suitable for an operating temperature of not less than 90°C (194°F).

• Motor Starting Exception: Other conductor insulation types are permitted specifically for motor starting service.

SLIDE 4 (WRAP-UP)

💡 Apprentice Pro-Tip: Always maintain at least 12 inches of clearance from combustibles or install a rated thermal barrier, and ensure your control wiring to resistors is rated for at least 90°C!

💬 Save this post for your next resistor bank wiring layout!

🔗 More code breakdowns and study tools at www.JoshTheSparky.com

← View Chapter 4 Home

← Article 470 Resistors and Reactors

← Back To Quick Hits Home