Rigid Metal Conduit The procedures for making the different types of bends discussed thus far have all been with a one-shot bender. The same bends can be made with rigid conduit. Ahickey bender can be used on rigid metal conduit also although the procedures are slightly different. For instance, to make a 90-degree bend in 1/2-inch rigid metal conduit, you should take the steps shown in figure 5-50. Let us say you need a 20-inch stub-up at the end of the 1/2-inch stick of rigid conduit. The steps for bending with a hickey are as follows:
1. Mark off 20 inches from the end of the conduit.
2. Determine the take-up for 1/2-inch rigid conduit. (See table 5-2.)
3. Make a second mark 6 inches back toward the end of the conduit.
4. Place the hickey at the second mark and pull about 30 degrees of bend.
5. Move the bender toward the 20-inch mark about 2 inches. Pull another 30 degrees of bend.
6. Move the bender to where the heel of the bender is on the 20-inch mark and complete the 90- degree bend.
Figure 5-50. - Bending a 90 with a hickey.
Since the hickey bender does not usually have degree markings on it, you have to estimate the amount of bend you are making with each bite. Small bites, as shown in figure 5-51, reduce the possibility of crimping or kinking the conduit.
Mechanical benders are designed to bend conduits using a built-in ratchet for fast, no kink, bends. Depending on the make and model, they are portable and easy to use. Equipped with different shoe sizes, they will bend EMT conduit from 3/4 inch through 2 inch, rigid and aluminum conduit 1/2 through 1 1/2 and IMC 1/2 through 1 1/4. Minimum stub lengths and take-up deductible inches vary from the hand benders just discussed. While the bending principles are the same, you will need to check with the manufacturers directions and bending charts.
In previous sections we have discussed types of conduits and the cutting, threading, and bending of conduit. Now, we will cover the requirements for installing the different types of conduit and how conductors should be pulled into them.
Several general requirements apply to all types of conduit installation: All raceways must be installed as a complete system before any conductors are pulled into them. In other words, the run of conduit, as described previously, including conduit, fitting, and supports, must be complete before the conductors are installed. A run of conduit should be as straight and direct as possible. When a number of conduit runs are to be installed parallel and adjacent to each other, you should install them all at the same time. The minimum-sized raceway that can be installed generally is 1/2-inch electrical trade size. Specific exceptions to this rule 5-27
Figure 5-51. - Bending with a hickey using small bites.Continue Reading