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3-3 Types of Benders

The procedures for making the different types of bends discussed this far have all been with an EMT bender. The same bends can be made with a hickey bender, although the procedures are slightly different. For instance, to make a 90º bend in 1/2-inch rigid-steel conduit, several steps must be used (Figure 3-11).

Figure 3-11. Making a 90° bend with a hickey bender

In the following example, you are going to make a 90° bend with a 20-inch stub in 1/2-inch rigid-steel conduit. The steps for making a bend with a hickey bender are as follows:

Step 1. Make a mark 20 inches from the end of the conduit.

Step 2. Determine the take-up for 1/2-inch rigid-steel conduit (Table 3-1, page 3-4).

Step 3. Make a second mark 6 inches back from the first mark toward the end of the conduit.

Step 4. Place the bender at the second mark and make about a 30º bend.

Step 5. Move the bender toward the 20-inch mark (about 2 inches). Make another 30º bend.

Step 6. Move the bender to where the heel of the bender is on the 20-inch mark and complete the 90º bend.

Since the hickey bender does not usually have degree markings on it, you must estimate the amount of bend you are making with each bite. Small bites reduce the possibility of crimping or kinking the conduit.

Power benders are used for bending larger sizes of EMT and rigid-steel conduit. They are also used where many bends must be made, regardless of the size of the conduit. They come in many types and sizes. The most common power bender is hydraulic. It is used to bend all types of bendable conduit. Hydraulic benders use either a hand pump or an electric pump to move a shoe that does the actual bending.

Figure 3-1 shows a hydraulic sweep bender that uses a hand pump. By using different-size bending dies at different locations on the tie bar, the bender can be used to bend several types and sizes of conduit. The procedures for making the different types of bends with power benders are very similar to those used with manual benders. The main difference is that with power benders the take-up for 90º bends and the distance between the bends for offsets will not be the same as those shown in Table 3-1, Table 3-3. This is due to the fact that you are dealing with larger sizes of conduit or the shoes of the bender give a different radius of bend. Because there are so many different types and manufacturers of benders, be sure to check the manufacturer's instructions before making any bends.

PVC is used primarily in underground or permanently wet locations and must have a separate equipment grounding conduct installed. Allowance must be made for this conductor when the maximum number of conductors permitted by the NEC is calculated.

PVC elbows and offset fittings are available for standard bends. For other bends, a special device called a hotbox must be used. The hotbox electrically heats the PVC and softens it so that it can be bent to the desired shape (Figure 3-12). Before heating the PVC section (especially sizes 2 inches and larger), plug both ends. This traps air in the conduit. The air, heated in the hotbed, expands to prevent kinks or dislocation of the conduit when it is bent.

Figure 3-12. Hotbox

PVC is durable, easy to work with, and moderate in cost. It is particularly well suited to areas where resistance to moisture and corrosion is essential. The main disadvantage of PVC is that joints cannot be taken apart after they are cemented.

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