straight line between junction boxes. If the spacing between raceways is 1 inch or more, the raceway may be covered with only 1 inch of concrete. All the joints in the raceway between sections of ducts and at junction boxes should be made waterproof and have good electrical contact so that the raceways will be electrically continuous. Metal raceways must be properly grounded.
To establish outlets in a preset system after the finish is in place, you have to determine the location of the insert. Inserts can be located by using an insert finder. Once inserts are located, the flooring is chipped down to expose the insert cap. The cap is removed and a hole cut in the duct so the wires can be fished through and connected to the receptacle.
The following procedures should be used to install an outlet fitting at any point in a completely enclosed underfloor fiber raceway:
1. Locate the duct line.
2. Cut a hole in linoleum or other floor covering.
3. Chip a hole down to duct.
4. Cut a hole in the duct.
5. Screw insert into the. duct.
6. Anchor the insert with grouting compound.
7. Screw the outlet into the insert.
The special tools, provided by the manufacturer, for this purpose should be used to ensure satisfactory workmanship.
Combination junction boxes accommodating the two or three ducts of multiple-duct systems may be used, provided separate compartments are furnished in the boxes for each system. It is best to keep the same relative location of compartments for the respective systems throughout the installation.
All the joints in or taps to the conductors must be made in the junction boxes. No joints or taps should be made in the ducts of the raceway or at outlet insert points.
An interior system above grade starts at the service drop and covers all the conduit layouts (excluding in- the-slab), communication, power, and lighting circuits. You must be aware of the NEC® rules that govern industrial and residential interior electrical systems. To gain additional knowledge, you may read the following: Standard Handbook for Electrical Engineers and the American Electrician's Handbook.
Follow the construction blueprints and speci- fication when laying out conduit runs. Remember, most prints will not show the direction of the conduit run. They only direct you to install a circuit from the distribution panel to a location where a electrical apparatus will be serviced. When you install any circuit, complete the service installation with the shortest route possible.
Properly bent conduit turns look better than elbows and, therefore, are preferable for exposed work (fig. 5-1). If bends are formed to a chalk line, draw the chalk line as suggested in figure 5-2. The conduits can
Figure 5-1. - Right-angle turns with elbows.
Figure 5-2. - Forming a conduit to chalk lines.Continue Reading