A back-to-back is a U-shaped piece of conduit with a ninety at each end, laid out so the distance from the back of one ninety to the back of the other matches the space it must fit, such as between two walls or across a doorway. The first ninety is bent as a stub-up, then the second mark is measured from its back and lined up with the bender's star or back-of-bend mark instead of the arrow.
Back-to-back across the doorway, 48 inches outside to outside, use the star on the bender for the second one.
Also heard as
- back to back
- U bend
Related terms
Stub-up
Ninety-degree bend that brings conduit straight up from a floor or out from a wall to a set height.
Ninety
Shop name for a 90-degree conduit bend, whether factory-made or bent on site.
Gain
Length saved because conduit turns around a curve instead of a sharp corner, used when cutting pipe to length.