22.5 degree conduit offset: multiplier and shrink

Why electricians bend 22.5 degrees

Twenty-two and a half degrees is exactly half of 45°, which is why it shows up so often. It is the outer-bend angle of the standard 3-point saddle, and it is also a good offset angle when 30° would run out of room but 15° would take too much. With a multiplier of 2.613, a 4" offset needs 10 7/16" between the bends, compared with 8" at 30°.

On a hand bender the 45° center notch is the mark you can count on. Some degree scales also show 22 1/2. Where yours does not, it is half of the 45° line, or halfway between the 15° and 30° lines. Bend a trial piece of scrap against a level or an angle finder once, and you know where your bender puts it.

22.5 degrees against 30 degrees

The rule of thumb for 22.5° is 2.6 for the multiplier and 3/16" per inch of shrink, which is close to the exact 0.199". That makes it one of the more forgiving angles to round: on a 6" offset the rule is off by about 1/16" on the shrink and 1/16" on the spacing.

The same angle in a 3-point saddle

Each half of a 3-point saddle is an offset at 22.5° the height of the obstruction. So the distance from the center mark to each outer mark is the same number as the distance between bends for an offset of that height.

A 22.5 degree offset in practice

Say a pipe crosses your path and the conduit has to move 4". At 22.5° you mark the bends 10 7/16" apart and allow 13/16" for shrink. That is a long, smooth jog that leaves two gentle bends for the wire to follow, and it asks for noticeably less room than 15° would.

The two bends must match. A quick check is to lay the finished conduit on a flat floor and look for rocking: a pair of bends that are really 20° and 25° leaves one end in the air.