Bending an offset
An offset moves the conduit over by a set amount and carries on parallel to where it started: one bend takes it off the line, a second bend of the same angle brings it back. Use it to clear a beam, a box or another pipe, or to step off a wall into a box.
What to measure
- Offset height: how far the conduit has to move, center of conduit to center of conduit. Measuring the bottom of the conduit before and after gives the same number.
- Angle: both bends are bent to it. Shallow angles need more room but pull easier and leave less shrink; 30° is the usual choice, 45° for a tall offset in a tight space.
- Distance to the obstruction (optional): from the end of the conduit to the face of the obstruction. Choose whether the offset has to be finished by then (the usual case) or start after it.
How to bend it
- Enter the offset height and pick the angle. If you gave a distance, the marks are measured from the conduit end; otherwise they are measured from the first mark, so put that mark where the offset should start.
- Mark both positions on the conduit. Each mark lines up with the arrow on the bender (or with the bend center, if you have set marks on bend center).
- Put the first mark on the arrow with the hook facing the end, and bend to the angle.
- Slide the conduit to the second mark, roll it half a turn so the bend goes back the other way, and bend to the same angle. Both bends are made with the hook facing the same end.
- Sight down the conduit to check the two legs are parallel and the bends are in the same plane before you install it.
Where the numbers come from
With the multiplier method the bends are treated as sharp corners, so the distance between them is the offset height divided by the sine of the angle (the multiplier), and the shrink is the height times the tangent of half the angle. A real shoe bends on a radius, which cuts each corner and uses a little less conduit than the sharp corner would. The app works that difference out from your bender’s centerline radius, so its numbers are slightly smaller than the chart’s, and they match what the bender actually does.
between bends = height ÷ sin(angle) − g(angle)shrink = height × tan(angle/2) − 2·g(angle)- Offset height
- 6"
- Angle
- 30°
- Distance to obstruction
- 40"
- Between bends
- 11 15/16" (12" by multiplier)
- Shrink
- 1 1/2" (1 5/8" by multiplier)
- Marks from the end
- 26 7/8" and 38 7/8"
If it turns orange or red
Red means the two bends would run into each other: the offset is too small for this angle on this shoe. Orange means there is some straight conduit between them, but less than the shoe needs to grip. Use a smaller angle, or a bigger offset if the job allows. The angle buttons are colored the same way before you pick one.