Shrink is the length a conduit run loses when an offset or saddle is bent into it, because part of the pipe now travels sideways. It depends on the angle and depth: about 1/16 inch per inch of offset at 10 degrees, 3/16 at 22.5, 1/4 at 30, 3/8 at 45 and 1/2 at 60. When working toward an obstruction, the shrink is added to the first mark so the bend lands in the right place.
Four-inch offset at 45s, that's an inch and a half of shrink, add it to your first mark or you'll come up short.
Also heard as
- shrinkage
- offset shrink
Related terms
Offset
Two equal bends in opposite directions that shift a conduit run sideways to clear an obstruction or enter a box.
Saddle
Set of bends that carries conduit over a pipe or obstruction and back down to its original line.
Gain
Length saved because conduit turns around a curve instead of a sharp corner, used when cutting pipe to length.