Offsets: Calculation, Layout, and Hand Bending

What an Offset Does

An offset is a pair of bends in the same plane that shifts a conduit run sideways or vertically to clear an obstacle—a beam, pipe, duct, or the edge of a panel—then returns the run to its original direction. Because both bends must be equal in angle and perfectly aligned, offsets are one of the first real tests of a bender's accuracy. Get the math right before you touch the bender and the conduit will drop into place; skip the math and you waste material and time.

The Multiplier Method

Every bend angle has a fixed multiplier that converts obstacle height into the distance you must separate the two marks on the conduit.

| Bend Angle | Multiplier | Shrink per inch of height |

|-----------|------------|---------------------------|

| 22½° | 2.6 | 3/16″ (≈ 0.19″) |

| 30° | 2.0 | 1/4″ (0.25″) |

| 45° | 1.4 | 3/8″ (≈ 0.37″) |

Mark-to-mark distance = obstacle height × multiplier

Shrink = obstacle height × shrink constant

Shrink is the amount the overall run shortens after bending. You must add it back when you cut conduit to a finished length or your run will come up short at the box.

Layout Procedure

1. Measure the obstacle height from the finished surface (or top of the pipe to be cleared) to the centerline of the existing conduit run.

2. Calculate mark-to-mark distance and shrink using the table above.

3. Choose the first bend mark location based on where the offset must begin. Mark it with a pencil line all the way around the conduit—a partial mark causes twists.

4. Measure the mark-to-mark distance from the first mark and draw the second mark the same way.

5. Note in your bending log: obstacle height, angle chosen, mark-to-mark distance, calculated shrink, and cut length if applicable.

Making the Bends

Foot benders (hand benders) for EMT have an arrow, a star or teardrop, and degree markings on the hook. For offsets you use the arrow mark.

1. Slide the conduit into the bender hook so the arrow aligns with the first mark.

2. Orient the bender so the handle stands roughly vertical. Keep one foot firmly on the bender footrest.

3. Apply smooth, even pressure—no jerking—until the desired angle reads on the bender's degree indicator or the conduit aligns with a reference angle on the floor.

4. Without removing the conduit from the bender, roll it 180° (flip it over) so the second mark aligns with the arrow and the bend you just made faces down.

5. Apply the same angle at the second mark, bending toward the first bend.

6. Lay the finished offset on the floor. Both legs must be parallel; use a torpedo level on each leg to confirm they are within 2° of level (or of each other if the run is not horizontal). If the legs are not parallel you have a dog-leg; if one leg is rotated relative to the other you have a twist.

Correcting Common Errors

Dog-leg (legs not parallel): One bend angle is greater than the other. Slightly overbend the shallow side or use a bender with a more precise degree stop.

Twist: The conduit rotated between bends. Return to the start; use a full circumference pencil mark and hold the conduit against your body or a straight edge as you make the second bend.

Wrong height: Measure the actual offset with a tape or combination square. If it is high, the angle is too steep; if low, the angle is too shallow. Recalculate and rebend on a new piece.

Shrink not accounted for: The run is short at the box or fitting. Always add shrink to your cut length before cutting.

Safety in the Lab

• Cut ends are sharp. Ream every cut end with a pipe reamer immediately after cutting. Wear leather gloves when handling freshly cut conduit.
• Benders can pinch. Keep fingers away from the hook area during the bend stroke.
• No overhead bending. Always bend with the bender on the floor; losing control of a long stick overhead can cause impact injuries.
• Eye protection (safety glasses) required whenever cutting or reaming conduit; chips and burrs can be ejected unexpectedly.
• Inspect conduit before bending. Kinked, dented, or corroded EMT will crack at the bend point and must be discarded.
• Keep your bending area clear of tripping hazards; conduit sticks protrude and move unexpectedly during bending.