scale, you can make accurate bends. To assure easy portabiliy, the manufacturer has designed the pipe supports for use as rollers; and parts are made of light- but-strong aluminum alloy whenever possible.
In the bending process, if the pipe is bent to the correct scale reading, overbends will not result. However: if you need to correct an overbend, you must follow the manufacturer's instructions that cover the bender that you are using.
As mentioned earlier, bending conduit is an art. The more you practice, the better you will be. Most bending charts show information on how to make bends to 15°. 30°, 45°, 60°, 90°, 180° and offset bends. When degrees of bend other than these are required and it is important that the bend be accurate. the Bending Degree Indicator should be used. The Bending Degree Indicator is extremely accurate and is very easy to use. The indicator also should be used when making segment bends to center radii greater than those of the bending shoe.
To install conduit overhead and underground properly, you need to review the appropriate articles of the Code. Conduit should run as straight and direct as possible. There should never be more than the equivalent of four right-angle bends between outlets or fittings.
In installing exposed conduit runs where there are several conduits in the run. it is usually better to carry the erection of all of them together. rather than to complete one line before starting the others. If all are carried together. it is easier to keep all the raceways parallel. particularly at turns. and chances are that the job will look better.
Conduit can be supported on surfaces with pipe straps made in one-hole and two-hole types. On wooden surfaces, wood screws secure the straps in position. On masonry surfaces, machine screws that turn into lead expansion anchors can be used. Wooden plugs should never be used because no matter how well seasoned a plug appears to be, it usually will dry out to some extent and loosen in the hole. When laying out multiple-conduit runs, you must keep in mind the spacings between the conduits to permit proper placing of the straps. The screw-hole dimension (see table 5-4) enables you to order screws of the proper diameters to support the straps.
The Code states that rigid-metal conduit will be firmly secured within 3 feet of each outlet box, junction box, cabinet, or fitting. The Code permits this distance to be increased to 5 feet where structural members do not readily permit fastening within 3 feet. Rigid-metal conduit will be supported at least every 10 feet; except that straight runs of conduit made up of
Table 5-4. - Spacings Requirements When Laying Out Multiple-Conduit Runs
|Size of conduit (inches) Conduit||Conduit width of opening (inches)||Conduit height of opening (inches)||Width of conduit strap (inches)||Distance between centers of screw hole (inches)||Diameter of scew hole (inches)||Size of wood screw required|
|1/4||9/16||17/32||5/8||1-9/16||0.20||No. 8 × 5/8"|
|3/8||1 1/16||21/32||5/8||1-3/8||0.20||No. 8 × 3/4"|
|1/2||7/8||25/32||5/8||l-5/8||0.20||No. 8 × 3/4"|
|3/4||1/18||1||3/4||2-1/8||0.22||No. 10 × 3/4"|
|1||1-3/8||1-11/32||3/4||2-3/8||0.22||No. 10 × 7/8"|
|1-1/4||1-3/4||1-5/8||1-13/16||2-3/4||0.22||No. 10 × 1"|
|1-1/2||2||1-7/8||1-13/16||3||0.22||No. 10 × 1"|
|2||2-1/2||2-5/16||1||3-3/4||0.22||No. 10 × 1- 1/4"|
|2-1/2||2-3/4||2-15/16||7/8||4-3/3||0.25||No. 11 × 1- 1/4"|