140 Section 3 Installation Copyright Goodheart-Willcox Co., Inc. PROCEDURE Stub Bend A stub bend d is a 90° d d bend that usua u al ly brings a horizonta nt al run of conduit up or o r down to an outlet box. b Practicing this basic i c bend will help you b be come familiar with the t he conduit bender. See S e Figure 10-5. 1. Measure the height t of the total bend. This is typically from the he bottom of the horizontal conduit to the he bottom of an electrical boxx (if the bend nd is pointing upward). Subtra r ac t t the radiu i us of the conduit bender from o m the th total l h he ight. The radius should be e no n ot ed on the h e head of the bender. The resulting e su lt num- ber is the distance to mark from fr om the end of the conduit. For example, e if if the t total height needed is 10″ and the e be b b en der’s radius is 5″, ″ mark the conduit 5″ 5 ″ from f ro the end. ″ 2. Place the condu d ui t t i in the bender with the mark aligned ed to t o the bender’s arrow. 3. Press down wn on o the foot pedal of the ben e nd er (while guid g ui di ng the handle to keep the th bend perpend rp n di cular to the floor) until the th stub is 90°. fl Apply A p p pl pressure on the bender er with your foot. Your Yo hand should only guide id the direction of the bend. 4. Use a torpedo level e l t to confirm that the fi stub is vertical. When W h the horizontal sec- tion of the conduit o nd is level, the stub should ho be plumb (p ( pe rfectly vertical). 10.1.3 Bending Metallic Conduit The purpose of bending conduit is to route it around corners and over obstructions. There are numerous specially manufactured fi ttings fi available that can be used to make turns in conduit, but bending is usually preferable to using fi ttings. A fi field bend fi is a bend that is made on the construction site. This generally saves time and is far more economical than installing fi ttings. fi Most bends in EMT are made with a hand tool called a conduit bender. Always use the correct size of bender for the conduit you are bending. This tool is designed to create a bend with the proper bend radius. The NEC lists the minimum radius of conduit bends in Chapter 9, Table 2. Typical bends include stub (often called a stub-up), back-to-back, offset, and saddle. The following sections will help you make these fun- damental bends. Bending conduit is an impor- tant skill that you can master with practice. Offset Bend The offset bend is used when the conduit must go around an obstruction or when the plane of the conduit must change slightly. Generally, off- sets may be done at almost any angle, but shal- low bends (those at smaller angles) are easier to pull wires through than deeper bends. Deeper bends bring the offset closer to the obstruction but make it more diffi to pull the wires. ficult Goodheart-Willcox Publisher Figure 10-4. The burr created by cutting EMT must be removed or it may damage the insulation when wires are pulled through the conduit. Removing Burrs from Metal Conduit Use a flat file on the outside Use a round file on the inside Deburring tool for outside and inside