Quick Hits

Slide 1: Hook / Cover

⚡ NEC 2026 Quick Hit: FMC Fill & Area Limits ⚡

Running Greenfield on the job? FMC (Article 348) has different internal dimensions than rigid or EMT.

Don't guess your pipe fill—here’s your Chapter 9 breakdown from 3/8" to 4" 👇

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

Small FMC Trade Sizes:

• 3/8" (Metric 12)

  • 100% Total Area: 0.116 in²

  • Over 2 Wires (40%): 0.046 in²

  • ID: 0.384 in.

• 1/2" (Metric 16)

  • 100% Total Area: 0.317 in²

  • Over 2 Wires (40%): 0.127 in²

  • ID: 0.635 in.

• 3/4" (Metric 21)

  • 100% Total Area: 0.533 in²

  • Over 2 Wires (40%): 0.213 in²

  • ID: 0.824 in.

Slide 3: Mid & Large Sizes (1" - 4")

Medium to Large FMC Sizes (40% Fill Limit):

• 1": 0.327 in² (100% = 0.817 in²)

• 1-1/4": 0.511 in² (100% = 1.277 in²)

• 1-1/2": 0.743 in² (100% = 1.858 in²)

• 2": 1.307 in² (100% = 3.269 in²)

• 3": 2.827 in² (100% = 7.069 in²)

• 4": 5.027 in² (100% = 12.566 in²)

Slide 4: Field Takeaway & Wrap-Up

💡 Apprentice Pro-Tip:

Keep in mind that 3/8" FMC is only permitted under specific conditions (see NEC 348.20), like motor leads or fixture whips!

When calculating fill for 3/8", that 0.046 in² 40% cap fills up real fast with #12s. Always check your wire OD in Table 5!

💬 Save this for your next whip installation! 🔗 More code breakdowns & study tools at www.JoshTheSparky.com

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