10 degree conduit offset: multiplier and shrink

When a 10 degree offset makes sense

Ten degrees is the shallowest angle most people ever bend an offset at, and it pays for that gentleness in length. Every inch of offset height needs 5.759" of conduit between the bends: a 1" offset spans 5 3/4", and a 4" offset spans 23 1/16". That is fine on an open wall or a long ceiling run, and impossible in a short stub.

• Small jogs. Stepping off a flat surface or a stud edge into a box that sits proud of it, where the conduit only has to move an inch or less.
• Long, open runs. A shallow bend adds very little friction when you pull wire, and leaves the straight sections almost in line.
• Fine corrections. A pair of 10° bends takes out a small error in a run without leaving a visible kink.
• Not for tight spaces. If there is not room for the distance between bends, step up to a steeper angle and take the extra shrink.

Finding 10 degrees on your bender, and the rule of thumb

Hand benders usually carry a degree scale or a row of angle lines on the head, and the scale often starts at 10°. Check yours before you rely on it. If your head has no 10° line, set the bend with a level or an angle finder. Springback matters more on a shallow bend: the degree or two that conduit relaxes after you let go is a bigger share of 10° than of 45°, so measure the finished angle with the conduit out of the bender.

Crews round the multiplier to 6 and the shrink to 1/16" per inch. The multiplier is a little long, which only adds a hair to the spacing. The shrink is the number that slips: 1/16" is well under the exact 0.087", so the table shows how much it understates as the offset grows.

Worked example: a 2 inch offset at 10 degrees

1. Measure the offset height from conduit center to conduit center, not from edge to edge.
2. Mark where the first bend goes, then mark 11 1/2" further along the conduit for the second.
3. If you measure from the end of the conduit, add the 3/16" of shrink to the distance to where the offset has to finish.
4. Bend the first mark to 10°, roll the conduit half a turn, and bend the second to the same angle. Sight down the conduit to check the legs are parallel.