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How Many Wires Fit in 1-1/2 in IMC?

Largest same-size THHN counts for 1-1/2 in IMC, with notes on when intermediate metal conduit is chosen over EMT or RMC.
Raceway
IMC
Trade size
1-1/2 in
Default limit
40% for 3 or more
Method
Chapter 9 area

Same-Size THHN Counts

Uniform conductor examples for quick planning. Mixed pulls need the calculator.

Conductor sizeInsulationLargest passing countFill at that countCaveat
14 AWGTHHN / THWN-29139.7%Uniform-size example only
12 AWGTHHN / THWN-26639.5%Uniform-size example only
10 AWGTHHN / THWN-24239.8%Uniform-size example only
8 AWGTHHN / THWN-22439.5%Uniform-size example only
6 AWGTHHN / THWN-21738.7%Uniform-size example only
4 AWGTHHN / THWN-21037%Uniform-size example only
2 AWGTHHN / THWN-2736.4%Uniform-size example only
How Many Wires Fit in 1-1/2 in IMC?. Counts are computed from the same fill engine as the calculator and rounded down to the largest passing whole count.

What the 1-1/2 in IMC Count Actually MeansUniform THHN counts at the Chapter 9 percent limits for IMC. Mixed pulls, compact conductors and cable assemblies still need the calculator.

Run mixed-size conduit fill

Adjacent Trade Sizes

How 12 AWG THHN counts change across neighboring IMC sizes.

Trade size12 AWG THHN count10 AWG THHN count8 AWG THHN count
1-1/4 in493118
1-1/2 in (this page)664224
Largest passing same-size 12 AWG THHN counts for neighboring IMC trade sizes.

Where 1-1/2 in IMC Is Used

IMC installation context for 1-1/2 in.

IMC is chosen when more physical protection than EMT is needed without the weight of RMC. Fill for 1-1/2 in IMC uses IMC’s Table 4 area — not EMT’s.

Threading, fittings and support rules differ from EMT. Fill charts never certify that IMC is the right product for the location.

What Changes the Count

Checks that matter for IMC — not a shared six-bullet list.

  • Do not borrow EMT counts

    IMC and EMT trade sizes do not share identical internal areas. Use IMC-specific results.

  • Include all conductors in fill

    Count EGCs and neutrals in the fill total even when derating treats them differently.

  • Protection vs fill

    Choosing IMC for physical protection is separate from whether the pull fits. Resolve both.

  • Adjacent trade sizes

    Stepping up a trade size can add only a few conductors — or enough to avoid a second raceway. Check the adjacent table.

1-1/2 in IMC FAQs

How many wires fit in 1-1/2 inch IMC?
See the same-size THHN counts on this page. Mixed sizes require the conduit fill calculator with IMC selected.
Is IMC fill the same as RMC?
Not necessarily. Use the Table 4 area for the raceway you are installing. Adjacent pages exist for RMC where published.
Can I mix conductor sizes in IMC?
Yes. Sum each size/insulation group’s area. The uniform-size table on this page is only a planning shortcut.