How a conduit offset is laid out
An offset is two bends of the same angle that move the conduit over by the offset depth. The distance between the two bend marks is the depth times the multiplier for your angle. Bending also uses up a little conduit, the shrink, so the first mark goes that much past the obstruction.
spacing = depth × multiplier
shrink = depth × shrink per inch
mark 1 = distance to obstruction + shrink
mark 2 = mark 1 − spacing
Example (Bamford, Mike Holt): a 6" offset at 30°, 36" to the obstruction. Spacing 6 × 2 = 12". Shrink 6 × 1/4 = 1 1/2". Mark 1 at 37 1/2", mark 2 12" back at 25 1/2".
How to bend it
- Line mark 1 up with the arrow on the bender, hook facing away from mark 2, and bend to the angle.
- Roll the conduit 180° (half a turn) so the bend points the other way.
- Line mark 2 up with the arrow and bend to the same angle.
That is the layout in the Greenlee and Klein hand bender guides. Electric benders such as the Greenlee 555 lay out offsets from their own tables, so use the bender's manual for those.
Offset multipliers and shrink
| Bend angle | Multiplier | Shrink per inch of depth |
|---|---|---|
| 10° | 6 | 1/16" |
| 22½° | 2.6 | 3/16" |
| 30° | 2 | 1/4" |
| 45° | 1.4 | 3/8" |
| 60° | 1.2 | 1/2" |
Trade figures as printed in the Greenlee Site-Rite Use Guide, the Klein Conduit Bender Guide and Bamford's "Bending Conduit Using Hand Benders". The exact multiplier is 1 ÷ sin(angle): 5.759, 2.613, 2.000, 1.414 and 1.155. Not affiliated with Greenlee or Klein Tools.
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