CONDUIT 2 

Some of the terms used when bending raceway are defined as follows:

Back to Back bend‐ a 90° bend located a short distance away from a box, raceway fitting or another bend in the raceway

Box offset bend ‐ An offset bend that lifts the raceway up to the height of the opening of the box so that the raceway enters the box in a straight direction instead of a slight angle

Chicago Bender ‐ A ratcheting bender for larger raceway that usually is on wheels

Concentric bend ‐multiple 90° bends around a corner running parallel to each other, that all have the same center

Dog Leg ‐ A mistake in bending when two bends in a raceway do not line up with each other

Foot ‐ The part on the bender that the electrician puts pressure with his foot to keep the raceway in the curved track of the bender

Gain ‐ The distance a raceway will shorten when it bends in a curve around a 90°corner instead of going all the way to the corner. The gain can be calculated by taking 43% of the radius of the bend

Jamming ‐ A problem that occurs when pulling wires around bends that have been lost their round shape. This happens when three equal size wires are pulled into the raceway and the ratio of the diameter of one wire to the raceway’s inside diameter is between 1.8 and 3.2. The wires will lay side by side inside the bend and then get stuck when the raceway returns to its round shape

Kick ‐ A bend in the raceway, usually less than a 45° angle that changes the direction of the run

Kink ‐ The location where a raceway folded rather than bent smoothly while bending the raceway, usually from poor foot pressure

Offset bend ‐ Two equal but opposite bends in a raceway that allow the run to change to another plane

One Shot bender ‐ a bender that makes a complete bend in one step (not in segments)

Rise ‐ The distance that a raceway will offset or stub up

Run‐ A term used for a complete path of raceway or cable between two points, usually between boxes and/or panels

Segment bend ‐ A large bend formed by a series of smaller bends.

Sled‐Runner‐ A 90° segment bend made with a hickey bender that is not made up of equal smaller bends

Springback ‐ The amount a raceway will straighten out after the pressure of bending is released

Stub‐up bend‐ A 90° bend in raceway that is located very near the end of the raceway

Introduction to the Bends

The first type of bend is the stub up bend

A stub up bend is used to bring a raceway from under the floor up to a receptacle box or into a panel or wireway. It is usually between 12” and 24” high

Most of the time on other types of bends, we can mark the exact distance we want for a bend directly on the raceway and place the bender on one of the marks and bend it

But, because the stub up bend is so close to the end of the raceway, the bender must be placed on the back side of the mark that is made on the raceway

The electrician will need to deduct 5” or 6” from the height to compensate for bending in the "wrong" direction

Deduct 5” for ½” EMT tubing

Deduct 6” for ¾” EMT tubing, etc.

Making 90° Stubs There are three basic methods for making 90° stub-up bends.Methods 1 and 2 will produce pin-point precision accuracy;

method 3 is good enough when speed is paramount-such as when concrete is being poured at your heels on a concrete slab job

Method 1: Marking The Conduit From the desired stub-up height, subtract the appropriate “take-up” for the

bender and place a mark on the conduit at that distance from the end.

The tool “take-up” for stubs is constant on fixed radius benders

A symbol or benchmark (such as an arrow) is usually cast into the bender

Example: It will be noted that a ¾” bender has a 6” take-up. To make a 9” high stub-up using either ¾” EMT or ½” rigid conduit, subtract

6” from 9” and mark the conduit 3” from the end. Position the bender so the arrow is opposite the 3” mark and make a 90° bend.

(6” + 3” = 9”).

Method 1 is most commonly used but it is slower than the other two methods because of the time it takes to mark the conduit.

Method 2: Alignment With Folding RuleLay a folding rule (or tape measure) on the floor parallel with the conduit

The folding rule becomes your guide for correct positioning of the bender on the conduit so as to make whatever stub length you desire

Example One: To make a 9” stub in ¾” EMT, allow 6” for the take-up in the tool.

Position the rule so that the 6” digit of the rule is opposite the end of the conduit. Now locate the bender on the conduit so that its arrow is opposite

the 9” digit on the rule and bend. Result: a perfect 9” stub-up

Method 3: Thumbnail and Eyeball Method This is called the “thumbnail and eyeball” method-no ruler!.. .no marking!

Simply place your thumbnail on the conduit at the stub height distance you desire

Then position the conduit in the tool so that an imaginary plumb line from the outside heel of the bender groove is in alignment with your thumbnail, and

bend. For best results, bend on the floor.

Your accuracy will be . As good as your ability to “eye-ball” that imaginary plumb line. This method is usually accurate to plus or minus ¼ inch.. .

use Method 3 when speed is paramount.

Conduit take‐up Amount of Take‐Up for 90° Bends Using an EMT Bender

Size and Type of Conduit Take‐Up

1/2‐inch EMT:  5 inches

3/4‐inch EMT or 1/2‐inch rigid steel: 6 inches 

1‐inch EMT or 3/4‐inch rigid steel: 8 inches 

1 1/4‐inch EMT or 1‐inch rigid steel: 11 inches

In the following example, you are going to make a 90° bend using 1/2‐inch EMT conduit and the EMT bender. You are going to run the conduit from the top of a panel to the ceiling and then horizontally along the ceiling. Measure from the top of the panel to the ceiling. This will give you the stub length of 18 inches. Measure 18 inches from the end of the conduit and make a mark

Look at Table to find out what the take‐up is for 1/2‐inch EMT conduit.

The take‐up is 6 inches. 

Measure back 6 inches from the first mark toward the end of the conduit and make a second mark 

Hold the bender in one hand with the lip on the floor pointed toward the stub end. Use the other hand to place the conduit in the bender.

Align the bender arrow with the take-up mark. Put one foot on the footrest and hold the handle with both hands.

To make the bend, apply pressure on the footrest as you pull on the handle until the handle is parallel with the floor.

It is OK to go slightly beyond 90° with the bend, in fact it is preferred, because it is easy to bring it back to 90°.

You should now have a 90° bend with an 18-inch stub To see whether the bendwill fit properly, place it next tosomething that has a right angle(for example, in the corner wherethe floor and wall meet).

If the bend is more than 90°, you can stand on the running end and push out on the stub end, a little at a time, until it is 90°.

If the stub is too short or if the conduit is too long to push back, place the handle of the bender over the end of the stub and, with one foot on the 

conduit on the floor, spring the stub back (right‐angle bends should always be made with the conduit and the bender on the floor).

ACCURATE STUBS

Subtract take‐up from desired stub height. This gives distance at which to place B on bender from the end of the tube. To make 11", 90° bend with 1/2" tube, allow for 5" for take up as shown on diagram. With 3/4" tube, allow 6“ With 1" tube, allow 8"

The next type of bend is the back to back bend. 

A back to back bend is any bend that needs a 90° bend located  a predetermined distance away.

This is probably the most common type of bend.

A mark is made on the raceway at the exact distance that is needed for the 90° bend.

The back‐to‐back bend

This is actually two adjacent 90° bends made in the same piece of conduit. Make the first 90° bend with a certain amount of stub as described 

previously

To determine where to place the bender for the second bend, you must first have an outside‐to‐outside measurement

This measurement is the distance from the back of the first bend to where you want the back of the second bend

You must then transfer this measurement to the conduit and make a mark The easiest way to make a back‐to‐back bend is to turn the bender around, line up the star of the bender with your outside‐to‐outside 

measurement, and pull the bend in the opposite direction 

Although “back-to-back” is a term accepted by the electrical trade, it is really a misnomer. Actually, it means the distance from a fixed point on the conduit

to the back of a 90° bend. Determining the distance from a point on the conduit to the back of a ninety

(the distance between A and B) probably is required more than any other bend on the job

Some benders have built-in symbols on both sides of the bending groove as an aid to making perfect back-to-back bends.

For purposes of clarity in this class the “star-point” symbol is used

With the bender positioned in any given spot, the starpoint predicts where the back of the ninety degree bend will Lay.

Thus, if the back of the ninety is to end up 50 inches from a fixed point on the conduit, the 50 in. are measured off and marked, the star-point is then

aligned with the 50 in. mark and the bend is made.

On surface conduit runs, the backs of two nineties frequently must be made to fit snugly against both a ceiling and a wall

Here again, if the starpoint is used for both bends, they will fit perfectly against both wall and ceiling as though they were molded in place

The third type of bend is the offset bend. This bend is made up of two equal degree bends that are bent in opposite directions

This bend can be used when the run of raceway is changing elevations

Both marks are placed on the raceway before any bending takes place

A box offset is a small offset bend (usually two 10° bends) that is used to lift a raceway from the surface up to the height of the knockout of the box it is entering. This allows the connector to enter the box on a straight angle

Line up arrow on either sideof hook with guideline andmake 45° bend in tube.Reverse tube in bender andadjust so that X is lined upwith inch‐mark on bendercorresponding to depth ofoffset desired. Line up guidelinewith opposite arrow andmake second 45° bend. A true offset, in the same plane, will result between X and Y.

An offset bend is two equal bends in opposite directions. It is used to avoid contacting a part of the structure or to bring the conduit out from the 

structure to match a knockout in a box or panel.

Figure 3‐8 shows an offset into a utility box.

The angle of the bends in an offset depends on several things: the amount of offset that is needed, the amount of room there is where the offset is 

going to be placed, and the type of obstacle you are avoiding. 

The offset shown is usually about 1/2 inch deep, and the bends are about 8º angles. 

Often, these bends will need to be made on both ends of the conduit to enter two boxes. 

Speed is important on any job…but speed coupled with on pays a triple dividend ,saves time, saves waste, makes for a quality job.

Conduit bends should fit right the first time. Bad bends double the cost.. . Twice the labor, twice the conduit.

By following these simple rules you will wipe out waste.The technique works for any fixed radius bender.. .hand type, mechanical

ratchet type, hydraulic or electrically powered benders

What is the best angle of bend to use for various offset depths? For shallow offset depths (3” or 4”), 30° bends are best

It’s easier to pull wire through gentle 30° bends… and it is easier to calculate the needed distance between bends because the multiplier for 30° bends is

simply TWO For offsets 5” deep or more 45° bends are best. The multiplier for 45° bends is

1.4(offset depth x 1.4 = distance between bends) 45° bends for depths of 5” or more will look neater and trimmer. They take up

less room because they are more closely coupled.

Figuring distance between bends

Knowing the depth of offset needed, and having established the angle of bend to use, and the distance between bends, you then need to know:

Where to start the first bend This is easy! The “shrink per inch” for offset depth is shown in Column 3 table

B. If stringing pipe into (towards) an obstruction place the first mark Y beyond

the edge of obstruction, the amount of shrink calculated from Table B. If offsetting away from an

obstruction ignore the “shrink.”