Quick Hits

⚡ NEC 2026 Quick Hit: Article 344 - Rigid Metal Conduit (RMC) ⚡

Threading heavy pipe? Because Rigid (RMC) has thicker wall construction than EMT or IMC, its internal area is slightly tighter across most trade sizes.

Don't mess up your feeder fill math—here is your Chapter 9 Table breakdown from 1/2" to 6" 👇

Slide 2: Common Small Sizes (1/2" - 1")

Small RMC Trade Sizes:

• 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: 0.549 in²

  • Over 2 Wires (40%): 0.220 in²

  • ID: 0.836 in.

• 1" (Metric 27)

  • 100% Total Area: 0.887 in²

  • Over 2 Wires (40%): 0.355 in²

  • ID: 1.063 in.

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

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

• 1-1/4": 0.610 in² (100% = 1.526 in² | ID: 1.394 in.)

• 1-1/2": 0.829 in² (100% = 2.071 in² | ID: 1.624 in.)

• 2": 1.363 in² (100% = 3.408 in² | ID: 2.083 in.)

• 3": 3.000 in² (100% = 7.499 in² | ID: 3.090 in.)

• 4": 5.153 in² (100% = 12.882 in² | ID: 4.050 in.)

Slide 4: Field Takeaway & Wrap-Up

💡 Apprentice Pro-Tip:

Compare 2" RMC 40% fill (1.363 in²) to 2" IMC (1.452 in²) and 2" EMT (1.342 in²).

RMC gives you more room than EMT, but less room than IMC! Always check which metal pipe material is specified on your print before running your conductor fill math.

💬 Save this post for your next industrial feeder pull! 🔗 More code breakdowns & study tools at www.JoshTheSparky.com

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