1. Bending Electrical conduit
USING TRIGONOMETRY

2. Bending Conduit
Offset Bends are used when a conduit either needs to avoid an obstacle or needs to change elevation or plane

3. What Shape Does the Offset Make?

4. Where is the triangle?

5. Where is the triangle?

6. Trigonometric Functions

7. Trigonometry distance between bends hypotenuse offset rise Opposite
Adjacent
hypotenuse
Opposite
distance between bends
offset rise
Offset θ
Bend angle

8. How to put the functions into a calculator

9. Find the value for each function
Use the angle of 30°
sin 30°
cos 30°
tan 30°
csc 30°
sec 30°
cot 30°
Which answer is the easiest to use?

10. Trigonometry Adjacent hypotenuse Opposite distance between bends
offset rise
Offset θ
Bend angle
sin (θ) = O H
csc (θ) = H O
cos (θ) = A
sec (θ) = H A
tan (θ) = O
cot (θ) = A
Multiplier = distance between bends
offset rise
2 = H 5
2 = H
H = 2 x 5
H = 10

11. Cosecant Cosecant of 30º = 2 10”
hypotenuse
Opposite
Adjacent
30º
Cosecant of 30º = 2
The cosecant becomes our multiplier for
a 30º bend, which is a constant
value no matter what the length of the
sides of the triangle
The multiplier for a 30º bend will
always be 2
10” 5”

12. Try it Out
An electrician is running a conduit along a wall from the electrical panel to a box that will house a disconnect switch for a hot tub. The disconnect switch is mounted on a 4” deep structural post. The electrician must bend an offset so that the pipe will be on the same plane as the post. The electrician wants to use 30º bends What is the multiplier (cosecant) of a 30º bend?

13. Try it Out We know: Our offset rise (opposite side) is 4”
Adjacent
hypotenuse
Opposite
distance between bends
offset rise 4”
We know:
Our offset rise (opposite side) is 4”
Our multiplier (cosecant) for our 30º bend is 2
We need to solve for our distance between bends (hypotenuse)
30º

14. Try it Out
Adjacent
hypotenuse
Opposite
distance between bends
offset rise
To find the distance between bends (hypotenuse) we multiply the off-set desired (4”) by our multiplier (2). DBB = multiplier x offset 8” = 2 x 4”
30º

15. Shrink
When a conduit is bent around an obstacle, it “shrinks” in length
Shrink = the amount by which the total run that conduit can cover is reduced because of the extra length required to bend around an obstacle

16. Shrink Bend angles have shrink constants
The shrink constant for a 30º bend is about ¼”
Shrink = C (shrink constant) x O (offset rise in inches)
Shrink needs to be added to your calculations before starting your bend

18. Why is that 30º so POPULAR?
Easy math! – the offset multiplier is 2 and the shrink constant is ¼”

19. Try it Out
You are running a conduit along a wall from one lighting box to another lighting box. You encounter a 7 ½” tall exit sign which is 40” from the first lighting box. You must bend an offset so that the pipe can change elevation, get around the sign, and connect to the lighting box. You want to use 30º bends.
40”