Quick Hits

⚡ NEC 2026 Quick Hit: LFNC-B Fill & Area Limits ⚡

Installing standard "Carflex" or corrugated nonmetallic whip? LFNC-B (Article 356) is the most common liquidtight flex you'll touch in the field.

Here is your Chapter 9 Table breakdown from 3/8" to 2" 👇

Slide 2: Common Small Sizes (3/8" - 3/4")

Small LFNC-B Trade Sizes:

• 3/8" (Metric 12)

  • 100% Total Area: 0.192 in²

  • Over 2 Wires (40%): 0.077 in²

  • ID: 0.494 in.

• 1/2" (Metric 16)

  • 100% Total Area: 0.314 in²

  • Over 2 Wires (40%): 0.125 in²

  • ID: 0.632 in.

• 3/4" (Metric 21)

  • 100% Total Area: 0.541 in²

  • Over 2 Wires (40%): 0.216 in²

  • ID: 0.830 in.

Slide 3: Mid & Large Sizes (1" - 2")

Medium to Large LFNC-B Sizes (40% Fill Limit):

• 1" (Metric 27): 0.349 in² (100% = 0.873 in² | ID: 1.054 in.)

• 1-1/4" (Metric 35): 0.611 in² (100% = 1.528 in² | ID: 1.395 in.)

• 1-1/2" (Metric 41): 0.792 in² (100% = 1.981 in² | ID: 1.588 in.)

• 2" (Metric 53): 1.298 in² (100% = 3.246 in² | ID: 2.033 in.)

Slide 4: Field Takeaway & Wrap-Up

💡 Apprentice Pro-Tip:

Compare LFNC-B to LFNC-A: as you get into larger trade sizes like 1-1/2" and 2", LFNC-B actually has slightly less internal area (2" LFNC-B is 1.298 in² vs LFNC-A at 1.337 in²).

Always double-check which type of nonmetallic flex you are actually running before calculating max conductor fill!

💬 Save this for your next AC condenser or generator install! 🔗 More code breakdowns & study tools at www.JoshTheSparky.com

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