Limited access feeder raceway

A floor construction includes a metal floor decking having a plurality of parallel multi-cell cellular metal floor raceways each of which includes at least one cell for high voltage power wiring. This one cell has a first wiring opening defined in a top thereof. A limited access feeder raceway transversely spans and rests upon the cellular metal floor raceways. The feeder raceway includes an enclosed first wiring raceway separating bottomless second and third wiring raceways. The enclosed first wiring raceway has a plurality of spaced second wiring openings defined through a bottom thereof, one of said second wiring openings being located directly above and in registry with each of the first wiring openings. The feeder raceway includes a closed top having a plurality of spaced access openings defined therethrough, one of which access openings is located directly above each of the second wiring openings. A plurality of access units are mounted upon the feeder raceway, one being associated with each access opening. The access units extend upward from the closed top of the feeder raceway to about a floor level for providing access downward through the access openings into the first, second and third wiring raceways of the limited access feeder raceway and into the cells of the multi-cell cellular metal floor distribution raceways. A concrete floor is poured on top of the metal floor decking and over the closed top of the limited access feeder raceway up to the floor level. An alternative two cell bottomless limited access feeder raceway is also disclosed.

This invention relates generally to raceway systems designed to be placed 
in a floor, and more particularly, but not by way of limitation, to a 
limited access feeder raceway designed for use with cellular metal floor 
distribution raceways. 
BACKGROUND OF THE INVENTION 
There are several well known types of electrical raceway systems which are 
designed to be placed in a floor. There are, for example, "underfloor 
raceways" as defined in Article 354 of the National Electrical Code and 
"cellular metal floor raceways" as defined in Article 356 of the National 
Electrical Code. Raceway components designed for use in either of the two 
mentioned raceway systems, and conceivably in some other systems, can 
generally be referred to as raceway apparatus for placement in a floor. 
As used herein, the simple term "raceway" or the phrase "raceway apparatus 
to be placed in a floor", or the like are intended to refer in a generic 
sense to raceway systems which may be used as part of an "underfloor 
raceway" or of a "cellular metal floor raceway" or both. Where the term 
"cellular metal floor raceway" is used, it is intended as a reference to 
the particular type of system defined in Article 356 of the National 
Electrical Code. 
The raceway system disclosed in this application is designed primarily as a 
limited access feeder raceway for use in conjunction with a cellular metal 
floor raceway. It can conceivably, however, be utilized in other ways, and 
thus is generally referred to as a raceway apparatus to be placed in a 
floor. 
The floors of buildings are commonly constructed with a corrugated metal 
floor decking over which a concrete floor is poured. The metal floor 
decking will typically have portions thereof provided with a bottom plate 
so that the corrugations of the metal decking along with the bottom plate 
define enclosed cells in which electrical wiring can be placed. Typically, 
three adjacent corrugations will be enclosed on the bottom to form three 
parallel cells which are referred to as a multi-cell cellular metal floor 
raceway. 
Typically, such multi-cell cellular metal floor raceways will be placed at 
intervals of approximately six feet so that the cellular metal floor 
decking includes a system of parallel cellular metal floor raceways which 
extend across the width of the floor and are spaced at intervals of 
approximately six feet along the length of the floor. 
The cellular metal floor raceways defined within the metal decking are 
typically used as the distribution ducts for the electrical supply system. 
Additionally, a feeder raceway is typically laid across the top of the 
cellular metal flooring transversely to the direction of the cellular 
metal floor raceways. Generally, a raceway construction known as trench 
duct is utilized for the feeder raceway. A typical trench duct utilized 
with cellular metal flooring is shown in U.S. Pat. No. 3,886,702 to Fork. 
The trench duct lies across the top of the cellular metal flooring and it 
extends upward to the top floor level. A removable cover plate typically 
spans the trench duct and defines a portion of the floor. The trench duct 
is utilized to feed electrical cables to the various cellular metal floor 
raceways. 
Trench duct typically has been provided with one of two basic designs. The 
trench duct can either be bottomless as shown in U.S. Pat. No. 3,886,702 
to Fork, or the trench duct can include a bottom plate which has access 
openings which must be aligned with access openings in the cellular metal 
flooring. 
A number of problems are inherent in the use of trench duct to feed 
cellular metal floor raceways. Trench duct is typically noisy to walk on 
and often gives an undesirable springy, spongy feeling under foot. 
Additionally, the cover plate which spans the trench duct tends to bow from 
floor loading and often causes the floor finish to crack and break at the 
trim edges of the trench duct. 
Additionally, since the trench duct extends vertically through the entire 
depth of the concrete slab, it prevents the use of structural wire mesh or 
other reinforcing to strengthen the slab at the location of the trench 
duct. 
One alternative to conventional trench duct is the use of a limited access 
feeder duct. The limited access feeder ducts previously available have 
utilized a completely enclosed multi-cell duct having access openings in 
the bottom thereof for alignment with access openings in the cellular 
metal floor raceways. Access units mounted on the top of the limited 
access duct extend upward to the floor level to provide access to the 
feeder duct and the underlying cellular metal floor raceways at selected 
locations along the length of the feeder duct. One such system is that 
marketed as the Mac-Fab system of Mac-Fab Products of St. Louis, Mo. 
The present invention provides an improved construction for such a limited 
access feeder raceway designed for use with cellular metal floor raceways. 
SUMMARY OF THE INVENTION 
An improved floor construction including a cellular metal floor decking 
with a limited access feeder raceway system is provided. 
The cellular metal floor decking includes a plurality of parallel 
multi-cell cellular metal floor raceways each including at least one cell 
for high voltage power wiring, said one cell having a first wiring opening 
defined in a top thereof. 
The limited access feeder raceway transversely spans and rests upon the 
cellular metal floor raceways of the metal floor decking. The limited 
access feeder raceway includes an enclosed first wiring raceway separating 
bottomless second and third wiring raceways. 
The enclosed first wiring raceway has a plurality of spaced second wiring 
openings defined through a bottom thereof. One of these second wiring 
openings is located directly above and in registry with each one of the 
first wiring openings. 
The limited access feeder raceway has a closed top plate having a plurality 
of spaced access openings defined therethrough. One of the second wiring 
openings is located below each of the access openings. 
A plurality of access means are associated with the limited access feeder 
raceway, one being associated with each access opening. Each access means 
extends upward from the closed top of the limited access feeder raceway to 
about a floor level, for providing access downward through the access 
openings into the first, second and third wiring raceways and into the 
cells of the cellular metal floor raceways located therebeneath. 
A concrete floor is poured on top of the metal floor decking and over the 
closed top plate of the limited access feeder raceway up to the floor 
level. 
Numerous objects, features and advantages of the present invention will be 
readily apparent to those skilled in the art upon a reading of the 
following disclosure when taken in conjunction with the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, and particularly to FIGS. 1-3, a limited 
access feeder raceway segment is thereshown and generally designated by 
the numeral 10. The feeder raceway segment 10 includes first and second 
spaced-apart, substantially parallel channel-shaped side rails 12 and 14. 
A single or unitary closed top plate 16 spans the side rails and is 
fixedly attached thereto. The top plate 16 has a square access opening 18 
defined therethrough. 
An elongated upwardly open, channel-shaped raceway enclosure and divider 
means 20 extends generally parallel to the side rails 12 and 14 and is 
attached to and extends downward from the top plate 16, thus defining an 
enclosed first wiring raceway 22. As best seen in FIG. 3, the raceway 
enclosure 20 separates a space between side rails 12 and 14 into 
bottomless second and third raceways 24 and 26 located on opposite sides 
of the enclosed first wiring raceway 22. 
An access means or access unit 27 is fixedly attached to the top plate 16 
and extends upward therefrom for providing access from a floor level 28 
(see FIG. 4) downward through the access opening 18 into the first, second 
and third raceways 22, 24 and 26. 
As best seen in FIG. 3, the side rails 12 and 14 are permanently attached 
to the top plate 16 by means such as welding, riveting or other suitable 
means. It is noted that it would be possible to construct the top plate 16 
and the side rails 12 and 14 in an integral fashion such as by forming the 
same from a single sheet of metal. 
The channel-shaped raceway enclosure means 20 has first and second flanges 
30 and 32 which are attached to and extend downward from top plate 16 to 
define side walls 30 and 32 of the enclosed first wiring raceway 22. The 
raceway enclosure means 20 further includes a web 34 extending between 
lower ends of flanges 30 and 32 to define a bottom wall 34 of the enclosed 
first wiring raceway 22. 
As best seen in FIG. 1, the raceway enclosure means 20 spans the access 
opening 18. The top plate 16 defines a top wall of the enclosed first 
wiring raceway 22 except at the access opening 18 where a top 36 of 
enclosed first wiring raceway 22 is open to permit access thereto. 
A portion of the web 34 of channel-shaped raceway enclosure means 20 
spanning the access opening 18 has a circular wiring opening 38 defined 
therein. The wiring opening 38 is located directly below the access 
opening 18. 
As best seen in FIG. 3, the raceway enclosure means 20 includes 
horizontally outward extending lips 40 and 42 defined on the upper ends of 
flanges 30 and 32. The lips 40 and 42 abut a lower surface 44 of top plate 
16 and are permanently attached thereto by spot welds 46. As best seen in 
FIG. 1, the lips 40 and 42 terminate at edges 48, 50, 52 and 54 adjacent 
access opening 18. 
The flanges 30 and 32, web 34 and lips 40 and 42 of raceway enclosure 20 
are preferably integrally constructed. 
The side rails 12 and 14 and raceway enclosure means 20 have equal fixed 
vertical heights 56 so that the web 34 of enclosure means 20 and lower 
edges 58 and 60 of side rails 12 and 14 lie in a common plane 62. 
Turning now to FIG. 4, an isometric view is thereshown of a floor 
construction generally designated by the numeral 64 which includes the 
limited access feeder raceway segment 10. 
The floor construction 64 includes a corrugated metal floor decking 
generally indicated by the numeral 66. The metal floor decking 66 includes 
a plurality of parallel, multi-cell cellular metal floor raceways such as 
68 and 70. 
For example, the first multi-cell cellular metal floor raceway 68 includes 
a bottom plate 71 which defines three adjacent parallel closed cells 72, 
74 and 76. 
Similarly, cellular metal floor raceway 70 has a bottom plate 78 defining 
first, second and third cells 80, 82 and 84. 
Typically, of the three cells 80, 82 and 84, the middle cell 82 will be 
designated for high voltage power wiring, and the adjacent cells 80 and 84 
will be utilized for communication wiring and computer wiring, 
respectively. At intervals along the lengths of the cellular metal floor 
raceways 68 and 70, first wiring openings such as 86, 88 and 90 will be 
defined in the top of the cells. These first wiring openings 86, 88 and 90 
are placed so that they will be intersected by the raceways 24, 22 and 26, 
respectively, of the feeder raceway segment 10. 
The feeder raceway segment 10 preferably has a length 87 (see FIG. 2) equal 
to an interval 89 (see FIG. 4) between adjacent cellular metal floor 
raceways such as 68 and 70. 
The feeder raceway segment 10 is then located upon the metal floor decking 
66 so that the access unit 27 and wiring opening 38 are centered upon the 
cellular metal floor raceway 68 with the wiring opening 38 located 
directly above and in registry with an opening such as 88 in the top of 
the middle cell 74 of cellular metal floor raceway 68. The wiring opening 
38 in the bottom 34 of raceway enclosure 20 can generally be referred to 
as a second wiring opening 38 defined through the bottom of enclosed first 
wiring raceway 22, which is located directly above and in registry with 
the first wiring opening 88 of the high voltage power wiring cell 74. 
An advantage of the limited access feeder raceway segment 10 having only 
one enclosed raceway 22 and having the two bottomless raceways 24 and 26 
is that only one wiring access hole 38 needs to be aligned with wiring 
access holes such as 88 in the cellular metal decking. Then whatever other 
access openings, such as openings 86 and 90, are provided in the cellular 
metal floor raceway can easily be accessed through the bottomless raceways 
24 and 26 of the feeder raceway segment 10. This is contrasted to prior 
art limited access systems which have completely enclosed raceways so that 
wiring access openings in the bottom of all three raceways of the feeder 
raceway must be aligned with corresponding openings in the cellular metal 
floor raceways. 
The lower edges 58 and 60 of the side rails 12 and 14 of feeder raceway 
segment 10 are typically welded to the top of the metal floor decking 66. 
Although only one of the feeder raceway segments 10 is shown in FIG. 4, it 
will be understood that a plurality of those segments 10 will be placed 
end to end, with each segment 10 having its access unit 27 centered over 
the openings 86, 88 and 90 of one of the cellular metal floor raceways 
such as 68 or 70. 
Ends such as the ends 91 and 92 of feeder raceway segment 10 are designed 
to be abutted together and connected by means of threaded fasteners which 
are placed in holes such as 94 and 96 (see FIG. 3) in angle-shaped pieces 
98 located flush with the ends 91 and 92. 
Additionally, across the top of top plate 16 near the ends 91 and 92 are a 
plurality of holes 100. A channel-shaped connector (not shown) is laid 
across the abutted ends of the feeder raceway segments 10 and fastened 
thereto by threaded fasteners extending down into the openings 100 so as 
to further reinforce the connection between adjacent feeder raceway 
segments 10. 
Additionally, if the interval 89 between adjacent cellular metal floor 
raceways 68 and 70 is greater than the length of the feeder raceway 
segments 10, blank sections of feeder raceway which do not include an 
access unit 27 can be placed between feeder raceway segments 10 so as to 
provide an appropriate interval between access units 27 equivalent to the 
interval 89 between the cellular metal floor raceways in the particular 
metal floor decking 66 being utilized. 
A concrete floor 102 is poured on top of the metal floor decking 66 and 
over the enclosed top plate 16 of the limited access feeder raceway 
segment 10 up to the floor level 28. Preferably, a layer of reinforcing 
material 104, which may be wire mesh, or reinforcing bar, is imbedded in 
the concrete floor 102 and extends across and above the closed top plate 
16 of the feeder raceway segment 10 except at the locations of the access 
units 27. This provides for a greatly increased floor strength as compared 
to that which can be achieved with conventional trench duct which extends 
the entire depth of the floor along the entire length of the feeder trench 
duct. 
A height 166 of access unit 27 corresponding to a thickness of concrete 102 
over the top of top plate 16 will be in a range from about 11/2 inches to 
about 31/2 inches. The reinforcing steel 104 will typically be located 
from 1/2 to 1 inch below the surface 28 of the concrete 102. As is 
apparent in FIG. 4, the top walls such as 106, 108 and 110 of each of the 
cells 80, 82 and 84 of the multi-cell cellular metal floor raceways lie in 
a common plane so that the lower edges 58 and 60 of channel members 12 and 
14 and the bottom 34 of raceway enclosure 20 lie across and engage the top 
walls 106, 108 and 110 of each cell. 
When the concrete floor 102 is poured, various trapezoidal-shaped filler 
blocks (not shown) are placed in the troughs of the metal floor decking 66 
immediately under the side rails 12 and 14 to prevent cement from entering 
the bottomless second and third wiring raceways 24 and 26 of the feeder 
raceway segment 10. 
Turning now to FIG. 5, the details of construction of the access unit 27 
will be described. The access unit 27 includes a generally rectangular 
access frame or access unit pan 112. A rectangular inner opening 114 is 
defined through pan 112 along an innermost edge 116 of the angular cross 
section member 118 from which the pan 112 is formed. This rectangular 
inner opening 114 also generally corresponds to the access opening 18. 
The pan 112 includes four pan adjustment screw brackets 120 which are 
welded or otherwise fixedly attached to the angle-shaped members 118 and 
which protrude into the generally rectangular opening 114. 
The pan 112 has four ears 122 extending outward at the corners thereof 
through which screws 125 are placed to hold the pan 112 in place on top 
plate 16. 
A generally rectangular trim rail 124 is adjustably supported from pan 112 
by four trim adjustment means 126 located at the four corners of the pan 
112. Trim adjustment means 126 are used to adjust a height 128 of the trim 
rail 124 relatively to the pan 112. A layer of porous foam gasket material 
130 is glued to the outer wall of trim rail 124 and slides against the 
vertical wall of pan 112. 
Each of the trim adjustment means 126 includes a threaded bolt 132 having 
an annular shoulder 134 defined above a threaded portion 136, and having a 
head 138. The bolt 132 is received in a threaded bore 140 of pan adjusting 
screw bracket 120. 
A rail assembly adjustment bracket 142 has an opening 144 therein which is 
freely received about bolt 132 and rests on top of annular shoulder 134. 
There are four such brackets 142, one in each corner. 
The previously mentioned square trim rail 124 is formed of four side rail 
pieces, the ends of which abut each other as indicated at 146 in FIG. 1. 
Thus, the ends of two of the side rail pieces of trim rail 124 rest upon 
each of the rail assembly adjustment brackets 142. A threaded screw 148 
connects each side rail piece of trim rail 124 to the rail assembly 
adjustment bracket 142 at each corner. 
Thus, to raise the trim rail 124 and thereby adjust the height 128 thereof 
above the pan 112, the bolts 132 are rotated thus raising the rail 
assembly adjustment brackets 142 and the trim rail 124. 
A snap retainer ring 150 is disposed about each of the bolts 132 above its 
associated rail assembly adjustment bracket 142. 
The trim rail 124 has a groove 152 defined therein within which is received 
a cover plate gasket 154. 
In each corner, a tile trim spacer 156 lies freely on top of the trim rail 
124 with an opening 158 freely received about the head 138 of bolt 132. 
Finally, a square cover plate 160 fits relatively closely within the 
vertical walls of trim rail 124 and is attached to the trim rail 124 by 
four screws 162 (see FIG. 1) which thread downward into holes (not shown) 
in the trim rail 124 to hold the cover plate 160 in place. 
As is apparent in FIG. 1, the cover plate 160 has four openings 164 defined 
therein through which the heads 138 of bolts 132 can be accessed to rotate 
the same and thus adjust the height of the trim rail 124 and cover plate 
160 relative to the pan 112. 
When electrical cables are to be pulled into the feeder raceway segment 10, 
the cover plates 160 are removed to allow access down through the access 
openings 18 into the wiring raceways 22, 24 and 26 of limited access 
feeder raceway segment 10 and into the cells such as 72, 74 and 76 of the 
cellular metal floor raceways such as 68. 
EMBODIMENT OF FIG. 6 
Some electrical systems utilize only two different types of wiring and thus 
require only two separate raceways instead of three. FIG. 6 illustrates an 
alternative embodiment of the limited access feeder raceway designated 
generally as 10A. 
The raceway 10A of FIG. 6 is generally the same as the raceway segment 10 
of FIG. 3, except that the raceway enclosure and divider means 20 has been 
replaced with a simple raceway divider means 20A. There are only two 
raceways defined in the limited access raceway segment 10A, namely the two 
bottomless raceways 24A and 26A. 
The other parts of raceway segment 10A of FIG. 6 are the same as the 
corresponding parts of raceway segment 10 of FIG. 3 and are indicated with 
like numerals. 
The limited access feeder raceway 10A of FIG. 6 would be utilized with a 
cellular metal flooring system like that shown in FIG. 4, except that the 
wiring openings 86 and 90 would be aligned so that both could be accessed 
through raceway 24A, and wiring opening 88 would be placed for access 
through raceway 26A. 
Thus it is seen that the apparatus of the present invention readily 
achieves the ends and advantages mentioned as well as those inherent 
therein. While certain preferred embodiments of the invention have been 
illustrated and described for purposes of the present disclosure, numerous 
changes in the arrangement and construction of parts may be made by those 
skilled in the art which changes are encompassed within the scope and 
spirit of the present invention as defined by the appended claims.