An honest note first: there is no separate “parallel offset” button in
the app, because there does not need to be one. Parallel offsets are just two (or more)
identical offsets bent in matching sticks of conduit. Run the offset calculator
once per conduit, follow the discipline below, and the runs come out parallel and
evenly spaced.
The method: same angle, same reference
Pick one angle for every conduit — 30° is the standard.
Different angles on the two sticks means different shrink, and the runs will converge
or diverge down the wall.
Measure both sticks from the same reference point — the same
box, the same slab edge. If stick A is measured from the panel and stick B from a
column three feet away, the bends will not line up.
Keep the center-to-center spacing constant through the whole offset.
If the runs are 6" apart on center before the obstacle, they must be 6" apart
on center after it.
Cut both sticks to the same length. Identical offsets have identical
shrink, so identical sticks stay aligned end to end.
Worked example
Two 3/4" EMT runs, 6" apart on center, both need a 4" offset at
30° to clear the same beam. Each offset: mark spacing = 4 × 2.0 =
8", shrink = 4 × 1/4" = 1". Bend
both sticks with marks measured from the same end and the same reference, and both
offsets land in the same place — runs still 6" apart, couplings aligned.
Why parallel offsets go wrong
Mixed angles. One stick at 30° and the other at 45° gives
different spacing and different shrink. The runs will never look right.
Different references. Even a 1" difference in where you start
measuring shows up as staggered bends.
Bending one stick, then “eyeballing” the second. Mark
the second stick with the tape, from the numbers — not by holding it next to the
first.
Forgetting that shrink is identical. That is actually the good news:
because both offsets shrink the same amount, you cut both sticks the same and move on.
Three or more runs
The same discipline scales: one angle, one reference, constant spacing, identical
cuts. For racks of three-plus conduits, mark all the sticks before bending any of them
— it is the only reliable way to keep a whole rack honest.