Quick Hits

⚡ NEC 2026 Quick Hit: Article 350 - Liquidtight Flexible Metal Conduit (LFMC) ⚡

Running Sealtite / LFMC on the job? Because of its metallic core with an outer waterproof jacket, LFMC dimensions differ from standard flex and nonmetallic conduit.

Here is your Chapter 9 Table breakdown from 3/8" to 4" 👇

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

Small LFMC 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" - 4")

Medium to Large LFMC 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.)

• 3" (Metric 78): 2.990 in² (100% = 7.475 in² | ID: 3.085 in.)

• 4" (Metric 103): 5.077 in² (100% = 12.692 in² | ID: 4.020 in.)

Slide 4: Field Takeaway & Wrap-Up

💡 Apprentice Pro-Tip:

Notice that 5" and 6" sizes show dashes (—) in Chapter 9 Table 4—they aren't standard listed trade sizes for LFMC!

Also, watch out when grounding: LFMC is often limited as an equipment grounding conductor by 350.60, so you'll usually need to pull an explicit EGC inside, which counts toward your 40% fill limit!

💬 Save this post for your next motor or outdoor equipment hookup! 🔗 More code breakdowns & study tools at www.JoshTheSparky.com

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