bender, called a hickey (fig. 5-40), and the one-shot bender (fig. 5-41). The one-shot bender is normally made for EMT, but some are made to be used for both EMT and rigid. The one-shot bender was given this name because a full 90-degree bend can be made with a single motion. Conduit sizes up to 1-inch rigid or 1 1/4- inch EMT can be bent without much trouble with manual benders. Larger sizes are bent with mechanical or hydraulic benders. Hydraulic benders will be discussed at the second-class level.
Although a complete line of factory elbows (90, 45, or 30 degree) are available, bending PVC conduit (1/2 through 2 inch) is accomplished easily with the use of a PVC hot box. A PVC hot box is nothing more than a heater, enclosed by metal having a mirror finish on the inside with openings on each end. To bend PVC conduit, place the conduit inside the hot box, turn the switch on, rotate the conduit until it becomes flexible, remove the conduit, and bend it to the desired shape.
The hot box is a heater. If you leave the conduit in long enough, it will BURN. You should use gloves when bending PVC.
Conduit bending is a precise art form. You will use degrees, angles, measurements and prefigured deductions for radiuses and shrinkage. Combine all these calculations correctly and you will get a finished
Figure 5-40. - Hickey.
Figure 5-41. - One-shot hender.
product that is not only functional but pleasing to the eye, and something to be proud of.
90 DEGREE BENDS. - One of the most common bends you will make in the field is the right-angle bend, more commonly called a 90-degree bend, or just a 90. Anyone can make a 90 in a stick of conduit and then cut it off to make it fit the situation, but this practice wastes time and material. The secret is to bend the conduit in the right place so that you do not have to cut it. To accomplish this, there are some things you have to know. First, you need to know the distance from the end of the conduit to the back of the 90. This distance is called the stub-up. Second, the radius of the bend takes up a part of the stub-up. This part is called the take-up. The amount of take-up depends on the type and size of conduit you are bending. (See table 5-2.)
Table 5-2. - Conduit Take-up
AMOUNT OF TAKE-UP FOR 90° BENDS (ONE-shot Benders)
|SIZE AND TYPE OF CONDUIT||TAKE-UP|
|3/4" EMT OR 1/2" RIGID*||6"|
|1" EMT OR 3/4 RIGID*||8"|
|1 1/4" EMT OR 1" RIGID*||11"|
*IMC AND RIGID WILL BE THE SAMEContinue Reading