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Worked Problems

Conduit Bending Examples

12 solved conduit bending problems with step-by-step calculations. Covers offset bends, stub-ups, 3-point saddles, 4-point saddles, and segment bends. Based on NEC 2023 Chapter 9 Table 2 bend radii and NJATC CBF curriculum methods.

Example 1 — Offset Bend

6" Rise at 30° Angle

Problem: Conduit must clear a 6-inch beam. Use a 30° offset.

Given: Rise = 6", Angle = 30°

Step-by-Step Solution

  1. Find multiplier: 1 ÷ sin(30°) = 1 ÷ 0.500 = 2.000
  2. Mark-to-mark distance: 6 × 2.000 = 12.000"
  3. Find shrink constant: 1/sin(30°) − 1/tan(30°) = 2.000 − 1.732 = 0.268
  4. Shrink: 6 × 0.268 = 1.608" ≈ 1‑5/8"
  5. Mark_01 = 0". Mark_02 = 12".

Answer

Mark at 0" and 12". Subtract 1‑5/8" shrink from layout measurement.

Example 2 — Offset Bend

4" Rise at 45° Angle

Problem: Offset a conduit run 4" to clear an obstruction using the steepest standard angle.

Given: Rise = 4", Angle = 45°

Step-by-Step Solution

  1. Multiplier: 1 ÷ sin(45°) = 1 ÷ 0.7071 = 1.414
  2. Distance: 4 × 1.414 = 5.657" ≈ 5‑11/16"
  3. Shrink constant: 1.414 − 1.000 = 0.414
  4. Shrink: 4 × 0.414 = 1.656" ≈ 1‑11/16"

Answer

Mark at 0" and 5‑11/16". Subtract 1‑11/16" shrink.

Example 3 — Offset Bend

10" Rise at 22.5° Angle

Problem: Large 10" riser needs minimum angle to maximize run length.

Given: Rise = 10", Angle = 22.5°

Step-by-Step Solution

  1. Multiplier: 1 ÷ sin(22.5°) = 1 ÷ 0.3827 = 2.613
  2. Distance: 10 × 2.613 = 26.13" ≈ 26‑1/8"
  3. Shrink constant: 2.613 − 2.414 = 0.199
  4. Shrink: 10 × 0.199 = 1.99" ≈ 2"

Answer

Mark at 0" and 26‑1/8". Subtract 2" shrink.

Example 4 — Stub-Up

18" Stub, 3/4" EMT

Problem: Stub up 18 inches using 3/4" EMT conduit.

Given: Stub height = 18", 3/4" EMT (NEC bend radius = 4.5")

Step-by-Step Solution

  1. NEC minimum bend radius for 3/4" EMT = 4.5"
  2. Take-up = bend radius = 4.5" (mark from end of conduit)
  3. Developed length = radius × π/2 = 4.5 × 1.5708 = 7.069" ≈ 7‑1/16"

Answer

Place bender arrow/star at 4‑1/2" from end. Developed arc length = 7‑1/16".

Example 5 — Stub-Up

12" Stub, 1" EMT

Problem: Stub up 12 inches using 1" EMT conduit.

Given: Stub height = 12", 1" EMT (NEC bend radius = 5.75")

Step-by-Step Solution

  1. NEC minimum bend radius for 1" EMT = 5.75"
  2. Take-up = 5.75" (mark from end)
  3. Developed length = 5.75 × π/2 = 5.75 × 1.5708 = 9.032" ≈ 9‑1/32"

Answer

Mark take-up at 5‑3/4" from end. Developed length = 9‑1/32".

Example 6 — 3-Point Saddle

3" Obstacle, 22.5° Outer Angle

Problem: Saddle over a 3" pipe using 22.5° outer bends.

Given: Obstacle height = 3", outer angle = 22.5° (center = 45°)

Step-by-Step Solution

  1. Segment distance = height ÷ sin(22.5°) = 3 ÷ 0.3827 = 7.84" ≈ 7‑7/8"
  2. Mark_01 = 0"
  3. Mark_02 = 7‑7/8" (first outer bend)
  4. Mark_03 = 7‑7/8" × 2 = 15‑3/4" (center bend)
  5. Center bend angle = 2 × 22.5° = 45°
  6. Shrink ≈ height × shrink constant for 22.5° ≈ 3/16" per bend side

Answer

Three marks at 0", 7‑7/8", and 15‑3/4". Outer bends = 22.5°, center bend = 45°.

Example 7 — 3-Point Saddle

4" Obstruction, 45° Outer Angle

Problem: Saddle over a 4" obstruction using 45° outer bends.

Given: Height = 4", outer = 45° (center = 90°)

Step-by-Step Solution

  1. Segment = 4 ÷ sin(45°) = 4 ÷ 0.7071 = 5.657" ≈ 5‑11/16"
  2. Mark_01 = 0"
  3. Mark_02 = 5‑11/16"
  4. Mark_03 = 5‑11/16" × 2 = 11‑3/8"
  5. Center bend = 2 × 45° = 90°

Answer

Three marks at 0", 5‑11/16", 11‑3/8". Center = 90°.

Example 8 — 4-Point Saddle

3" Height, 6" Width, 30°

Problem: 4-point saddle over a 3"-tall, 6"-wide obstruction at 30°.

Given: Height = 3", Width = 6", Angle = 30°

Step-by-Step Solution

  1. Segment = height ÷ sin(30°) = 3 ÷ 0.500 = 6"
  2. Shrink per bend = 3 × (2.000 − 1.732) = 3 × 0.268 ≈ 0.804" ≈ 13/16"
  3. Dogleg = width + 2 × shrink = 6 + 2 × 0.804 = 7‑5/8"
  4. Mark_01 = 0"
  5. Mark_02 = 6" (first rise bend)
  6. Mark_03 = 6" + 7‑5/8" = 13‑5/8"
  7. Mark_04 = 13‑5/8" + 6" = 19‑5/8"

Answer

Four marks at 0", 6", 13‑5/8", 19‑5/8". Dogleg = 7‑5/8".

Example 9 — 4-Point Saddle

2" Height, 8" Width, 22.5°

Problem: Shallow 4-point saddle over a 2"-tall, 8"-wide obstruction.

Given: Height = 2", Width = 8", Angle = 22.5°

Step-by-Step Solution

  1. Segment = 2 ÷ sin(22.5°) = 2 ÷ 0.3827 = 5.23" ≈ 5‑1/4"
  2. Shrink per bend = 2 × (2.613 − 2.414) = 2 × 0.199 ≈ 0.398" ≈ 3/8"
  3. Dogleg = 8 + 2 × 0.398 = 8‑3/4"
  4. Mark_01 = 0"
  5. Mark_02 = 5‑1/4"
  6. Mark_03 = 5‑1/4" + 8‑3/4" = 14"
  7. Mark_04 = 14" + 5‑1/4" = 19‑1/4"

Answer

Four marks at 0", 5‑1/4", 14", 19‑1/4". Dogleg = 8‑3/4".

Example 10 — Segment Bend

90° Total, 5 Segments, 3/4" EMT

Problem: Make a smooth 90° bend in 5 segments using 3/4" EMT.

Given: Total angle = 90°, N = 5 segments, 3/4" EMT (bend radius = 4.5")

Step-by-Step Solution

  1. Angle per segment = 90° ÷ 5 = 18°
  2. Developed length = radius × (total angle in radians) = 4.5 × (π/2) = 4.5 × 1.5708 = 7.069"
  3. Mark spacing = developed length ÷ N = 7.069 ÷ 5 = 1.414" ≈ 1‑7/16"

Answer

5 marks spaced 1‑7/16" apart. Bend 18° at each mark.

Example 11 — Segment Bend

180° Total, 7 Segments, 1" EMT

Problem: Create a 180° sweep (U-bend) in 7 segments using 1" EMT.

Given: Total angle = 180°, N = 7 segments, 1" EMT (bend radius = 5.75")

Step-by-Step Solution

  1. Angle per segment = 180° ÷ 7 ≈ 25.7°
  2. Developed length = 5.75 × π = 5.75 × 3.1416 = 18.064"
  3. Mark spacing = 18.064 ÷ 7 = 2.581" ≈ 2‑9/16"

Answer

7 marks at 2‑9/16" spacing. Bend ≈25.7° at each mark.

Example 12 — Reverse Problem

Given Max Distance, Find Angle

Problem: You have a 6" rise but only 14" of available run. What angle fits?

Given: Rise = 6", max available mark distance = 14"

Step-by-Step Solution

  1. Solve for angle: θ = arcsin(rise ÷ distance) = arcsin(6 ÷ 14) = arcsin(0.4286) ≈ 25.4°
  2. 25.4° is between standard angles (22.5° and 30°).
  3. Check 30°: distance = 6 ÷ sin(30°) = 6 ÷ 0.500 = 12" — fits within 14" ✓
  4. Check 22.5°: distance = 6 ÷ sin(22.5°) = 6 ÷ 0.3827 = 15.7" — exceeds 14" ✗
  5. Use 30° — it is the larger angle that still fits the space.

Answer

Use 30° bend. Mark at 0" and 12". Verify 12" < 14" available. ✓

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