Conduit bending for industrial electricians: rigid, IMC and power benders

What industrial bending asks for

• Rigid (RMC) and IMC: threaded, heavier and stiffer than EMT, with a bigger radius and a different take-up at the same trade size.
• Power benders: mechanical (Chicago-style) and electric benders through 2", and hydraulic benders for the big sizes.
• Racks of parallel conduit on strut or trapezes, turning the same corner together.
• Segmented 90s and sweeps where a large radius is needed or there’s no shoe for it.
• Offsets and kicks around steel, ductwork and equipment.

A wasted stick of 3" rigid costs far more than a wasted stick of 1/2" EMT, and so does the time to cut, thread and bend it again. Getting the marks right the first time matters more here than anywhere.

Power benders, with their numbers sourced

BendMate has 34 benders with 400 shoe and conduit combinations; the mechanical, electric and hydraulic ones are part of Pro. Each bender page lists every shoe’s centerline radius, 90° deduct and gain, and where each number came from: the manufacturer’s manuals, catalogs or datasheets, or the NEC minimum where a manufacturer doesn’t publish a radius.

The same trade size can take a different deduct on each bender, so marks worked out for one machine are off on another:

Large sizes and the NEC minimum radius

NEC Chapter 9, Table 2 sets the smallest radius, measured to the centerline, that a field bend may have. Bends made on one-shot and full-shoe benders have one column; other bends have a larger one. Know which applies to your method, and check with your AHJ.

A segmented sweep is only as large as the radius you lay it out on, so choose that radius with the table in mind.

Racks, segmented 90s and whole sticks

In Pro, the rack builder bends a group of conduits through the same offset, 90, kick or saddle, all one size or mixed sizes, and gives each conduit its own marks. Segmented and compound 90s, rolling and parallel offsets, and several bends on one stick with the cut length are there too.

That radius is above the NEC minimum of 24" for other bends in 4" conduit. The free segmented 90 calculator on this site works out the same shot angle and spacing.

Springback and checking the bend

Rigid and IMC spring back more than EMT when the pressure comes off. BendMate doesn’t predict springback: it gives the marks and the angle to finish at, and how far the conduit springs back depends on your bender, shoe and conduit.

1. Bend a test piece in the size and conduit you’ll be running, and note how far it springs back.
2. Overbend by that much, then check the finished angle with BendMate’s level, which reads it from the phone’s tilt sensor.
3. If 90s come out long or short, correct the bender’s deduct in its specs, and every mark follows.
4. Check again when you change shoe, conduit or bender: benders vary, even two of the same model, and shoes wear.