When a fuse is suspected of being defective, it may be checked with a neon tester using the four-part procedure shown in figure 5-19.
1. First determine if the voltage is present at the top of the fuses from the incoming lines. (Light should glow.)
2. Determine if the voltage is passing through the fuse. (If the neon tester fails to light, one or both fuses are defective.)
3. Check the left fuse to see if the voltage is present. If the light glows, the fuse is good; however, if it fails to light, the fuse is defective. Shut off the power and replace the fuse.
4. Check the right fuse to see if the voltage is present. If the light glows, the fuse is good; however, if it fails to light, the fuse is defective. Shut off the power and replace the fuse.
To prevent electrical shock, do not replace the fuses unless the circuit is de-energized and then only with fuse pullers.
Bending conduit is an art. Like all forms of art, the more often it is done correctly, the more proficient the artist becomes. It is recommended that you attend the SCBT 240.2 course that covers bending and installation of electrical conduits using mechanical benders. Keep in mind that practice will improve your skills and always read and follow the manufacturer's instruction guide. Following the guide will normally assure that you make top quality bends in a safe and efficient manner.
Power benders are used for bending larger sizes of electrical metallic tubing (EMT), intermediate metallic tubing (IMC), and rigid conduit. Power benders come in many types and sizes. Some of the common ones are the hydraulic one-shot, sweep, and thin-wall benders. As for the mechanical benders, the thin-wall and sweep benders are common. The hydraulic benders use either a hand pump or an electric pump to move a shoe that does the actual bending. Figure 5-20 shows a hydraulic sweep bender that uses a hand pump. By using different sizes of bending dies at different locations on the tie bar, you can use this bender 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 the power benders, the take-up for 90-degree bends and the distance between bends for offsets will not be the same. This difference occurs because 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, remember to check the manufacturer's instruction guide before doing any bending.
In the following paragraphs, we will discuss some general information concerning power benders. This information does not replace the manufacturer's instruction guide, but only acquaints you with some basic functions and safety tips that you (as a crew leader) must be aware of.
When you are bending conduit, the bender must be in a horizontal position. When moving the bender any distance, place the pipe supports and pins in a 4-inch to 5-inch hole position. Then stand up the bender and roll it.
When connecting the high-pressure hose to the female quick-coupler on the end of the ram and the other end to the high-pressure pump female coupler, make sure that the quick-coupler is clean before making the connection. For the correct procedures for removing all the air from the pump and hoses, refer to the manufacturer's manual.
Some mechanical benders have an electrical power pump that is used to apply pressure on the ram. In this case, to operate the hydraulic pump, the motor must be running. Also, the quickest way to stop the advance of the ram is to stop the motor of the power pump.
Read the pump operating instructions before operating the pump. Always place the control lever in the return position before starting the electric motor pump.
Regardless of what hydraulic bender you use, you must always check the manufacturer's charts and tables for the minimum stub length. When theContinue Reading