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
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
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
INTERIOR SYSTEMS ABOVE GRADE
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 Electricians 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.