Quick Hits

⚡ NEC 2026 Quick Hit: Article 342 - Intermediate Metal Conduit (IMC) ⚡

Running IMC on the job? Because IMC has thinner walls than Rigid (RMC) but thicker walls than EMT, its internal area gives you a bit more room to breathe.

Here is your Chapter 9 Table breakdown from 1/2" to 6" 👇

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

Small IMC Trade Sizes:

• 1/2" (Metric 16)

  • 100% Total Area: 0.342 in²

  • Over 2 Wires (40%): 0.137 in²

  • ID: 0.660 in.

• 3/4" (Metric 21)

  • 100% Total Area: 0.586 in²

  • Over 2 Wires (40%): 0.235 in²

  • ID: 0.864 in.

• 1" (Metric 27)

  • 100% Total Area: 0.959 in²

  • Over 2 Wires (40%): 0.384 in²

  • ID: 1.105 in.

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

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

• 1-1/4": 0.659 in² (100% = 1.647 in² | ID: 1.448 in.)

• 1-1/2": 0.890 in² (100% = 2.225 in² | ID: 1.683 in.)

• 2": 1.452 in² (100% = 3.630 in² | ID: 2.150 in.)

• 3": 3.169 in² (100% = 7.922 in² | ID: 3.176 in.)

• 4": 5.452 in² (100% = 13.631 in² | ID: 4.166 in.)

Slide 4: Field Takeaway & Wrap-Up

💡 Apprentice Pro-Tip:

Notice there's no 3/8" trade size for IMC (starts at 1/2").

Also, compare IMC's 1/2" 40% fill (0.137 in²) to EMT's 1/2" 40% fill (0.122 in²)—that extra space in IMC can make a huge difference when you're pulling tight wire combinations!

💬 Save this post for your next pipe calculation or feeder run! 🔗 More code breakdowns & study tools at www.JoshTheSparky.com

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