Table of Contents
- 1 What is deduct in conduit bending?
- 2 How do you calculate conduit bending?
- 3 What do the marks on a conduit bender mean?
- 4 How many bends can you have in electrical conduit?
- 5 How big is a 90 degree bend deduct?
- 6 Can a conduit be used for a 90 degree bend?
- 7 How is the bend allowance and the bend deduction related?
What is deduct in conduit bending?
First on the list is to understand the term deduct; this is a measure of the amount the conduit will “shrink” in length when a hand bender is used properly. Work the bender onto the conduit with the conduit mark at the arrow of the bender.
How do you calculate conduit bending?
On the conduit, measure from the free end to be bent up the calculated number and mark the conduit. As an example, to bend 3/4” EMT conduit have a free end height of 8.5”, the table indicates to subtract 6” from the 8.5” which leave 2.5” from the end to bend up to make the mark.
How is bend offset calculated?
The formula used to determine the center to center distance between bends is: The center to center dimensions of the bends is equal to the desired size of the offset times the cosecant of the angle used to make the bends. C = 10 x 2, or C = 20″.
What do the marks on a conduit bender mean?
Bender Diagram Arrow: Used to line up offset and outer marks for saddle bend. C. Star: Indicates back of 90° bend, for back to back bends. D. Marks: The degree marks indicating the angle of the pipe bent.
How many bends can you have in electrical conduit?
National Electrical Code or NEC limits the total number of bends in one continuous run to 360 degrees or four 90 degree bends. It specifically states, “There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes.”
How do you measure bending tube?
The “Measure-Bend Method”
- Place a reference mark at the end of the tube from which you are beginning the measurements.
- Measure four inches from the reference mark and make a bend mark to indicate the first desired bend length.
- Bend the tube 90 degrees as described in the tech tip video.
How big is a 90 degree bend deduct?
not present Size of Conduit Radius of Bend Deduct for 90 degrees 1/2″ 4″ 5″ 3/4″ 4 1/2″ 6″ 1″ 5 3/4″ 8″
Can a conduit be used for a 90 degree bend?
Conduit comes in 10 foot lengths and can create an awkward bending situation when the stub length is over 60 inches. The reverse method for bending a 90 is an alternative that addresses this type of situation. This method is also used in back to back 90 degree bends. When using the reverse method the take up deduction is no longer needed.
How tall should a 3 / 4 ” EMT conduit be?
As an example, to bend 3/4” EMT conduit have a free end height of 8.5”, the table indicates to subtract 6” from the 8.5” which leave 2.5” from the end to bend up to make the mark. Tip: Advanced benders can lay a tape measure next to the conduit and perform the bending operations if the bend does not call for high degree of accuracy.
The bend allowance and bend deduction are two measures that relate the bent length of a piece of sheet metal to the flat length. The bend allowance describes the length of the neutral axis between the bend lines, or in other words, the arc length of the bend.