IMC Conduit

Features & Specifications

Allied IMC is precision manufactured for economical protection and long lasting value for the electrical raceway system. Manufactured from premium, work hardened steel combining electrical and mechanical performance with ductility. Allied IMC is resistant to impact and is easy to cut, bend and join for smooth, continuous raceways. Allied IMC is as strong, lighter in weight, and less expensive than Rigid. In fact, it can save you as much as 30% in overall costs. Intermediate Metal Conduit, covered by Article 342 in the National Electrical Code (NEC), is recognized as an equipment grounding conductor in Article 250 of the NEC and also provides excellent shielding from electromagnetic fields.

  • Light-weight ductile steel conduit for long life and easy bending
  • Weighs 1/3 less than rigid conduit
  • Saves up to 30% in cost over GRC
  • Hot galvanized exterior to increase corrosion resistance and protect against white rust
  • Interior coating creates a smooth, continuous raceway for fast wire-pulling
  • UL 1242 listed and manufactured in accordance with ANSI C80.6
  • True Color IMC special orders available
  • Available in trade sizes 1/2(16) thru 4(103)

The Allied Advantage
Allied IMC has a larger internal diameter than RIGID conduit to allow for easier fishing and wire-pulling. Allied IMC is also more “rigid” than RIGID to provide superior wiring protection in many applications.

The National Electrical Code recognizes Allied IMC for the same uses as RIGID, including all hazardous location (classified) applications.

Allied IMC uses the same threaded couplings and fittings as RIGID conduit, and the 3/4″ NPT threads (ANSI B1.20.1) are also full cut and galvanized after cutting. Color-coded end-cap thread protectors keep the threads clean and sharp, and also help to provide instant trade size recognition. Even sizes are color-coded orange, 1/2 trade sizes are yellow, and 1/4 trade sizes are green.


Allied’s IMC is hot galvanized using Allied’s patented inline Flo-Coat process. This process combines zinc, a conversion coating, and a clear organic polymer topcoat to form a triple layer of protection against corrosion and abrasion. The interior of Allied IMC is coated with a highly corrosion-resistant lubricating finish for easier wire-pulling. No need to worry about damage to the conduit system even when pulling through multiple 90° bends.

EMI Shielding
Allied IMC is very effective in reducing the effects of electromagnetic fields on encased power distribution circuits, shielding computers and other sensitive electronic equipment from the effects of electromagnetic interference.

For more information, visit GEMI (Grounding and Electro-Magnetic Interference) software analysis program.

Codes & Standards Compliance

IMC is covered by Article 342 of the National Electric Code (NEC). It can be installed in all occupancies and locations, including Class I, Division I hazardous locations. Allied IMC is listed to Underwriters Laboratories Safety Standard UL 1242 and meets ANSI C80.6. These standards have been adopted as Federal Specifications in lieu of WWC-581-Type 2. IMC is recognized as an equipment grounding conductor by NEC Section 250-118.

Installation of IMC conduit and elbows shall be in accordance with the National Electrical Code and the UL listing information. Allied IMC is listed in UL category DYBY. Master bundles conform to NEMA standard RN2.

Specification Data

To specify, IMC include the following: Intermediate Metal Conduit (IMC) conduit and elbows shall be equal to that manufactured by Allied Tube & Conduit Corporation. IMC shall be hot galvanized steel O.D. with an organic corrosion resistant I.D. coating and shall be Listed to UL Safety Standard 1242 and manufactured in accordance with ANSI C80.6. It shall be listed by a nationally recognized testing laboratory with follow-up service. Threads shall be hot galvanized after cutting.

Trade SizeMetric DesignatorAverage Outside Diameter*Average Wall Thickness**Approx Weight/100 Ft (30.5M)Quantity in Master Bundle
1 1/4351.63841.60.0852.1615871.71350411.8
1 1/2411.88347.820.0902.2919488.01100335.5
2 1/2632.85772.560.1403.56441200.0370112.9
3 1/2913.971100.860.1403.56629285.324073.2
*Outside diameter tolerances:
+/- .005 in. (.13mm) for trade sizes 1/2 (16mm) through 1 (25mm)
+/- .0075 in. (.19mm) for trade sizes 1-1/4 (36mm) through 2 (53mm)
+/- 0.10 in. (.25mm) for trade sizes 2-1/2 (63mm) through 4 (103mm)
**Wall thickness tolerances:
+ 0.15 in. (.38mm) and - .000 for trade sizes 1/2 (13mm) through 2 (53mm)
+ 0.20 in. (.51mm) and - .000 for trade sizes 2-1/2 (63mm) through 4 (103mm)
NOTE: Length = 10 ft. (3.05m) with a tolerance of +/- .25 in. (6.35mm)