CA1070510A - Method for forming wiring channels in a concrete floor - Google Patents
Method for forming wiring channels in a concrete floorInfo
- Publication number
- CA1070510A CA1070510A CA276,882A CA276882A CA1070510A CA 1070510 A CA1070510 A CA 1070510A CA 276882 A CA276882 A CA 276882A CA 1070510 A CA1070510 A CA 1070510A
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- trench
- ducts
- cover plate
- shaped channel
- forming
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Abstract
ABSTRACT
An improved method for forming wiring channels in a concrete floor. Parallel trenches are formed in a concrete floor slab when the slab is poured. A metal cover placed over each trench has a metal U-shaped channel attached thereto for dividing the trench into at least two and preferably three separate wire raceways with the center raceway completely shielded by the channel and cover. Access boxes are selectively positioned over knockouts in the cover plate. Metal channels are positioned to extend perpendicular to the trenches for forming main distribution ducts. A
concrete surface is then poured over the slab to extend flush with the tops of the access boxes and the main distribution ducts and a cover plate is attached to enclose the main distribution ducts. The resulting floor structure has embedded therein parallel wiring raceways spaced across the floor with spaced accesses into each raceway and main distribution ducts interconnecting the parallel raceways. If desired, concrete floor slabs with trenches and metal covers may be prefabricated for later use in constructing buildings.
An improved method for forming wiring channels in a concrete floor. Parallel trenches are formed in a concrete floor slab when the slab is poured. A metal cover placed over each trench has a metal U-shaped channel attached thereto for dividing the trench into at least two and preferably three separate wire raceways with the center raceway completely shielded by the channel and cover. Access boxes are selectively positioned over knockouts in the cover plate. Metal channels are positioned to extend perpendicular to the trenches for forming main distribution ducts. A
concrete surface is then poured over the slab to extend flush with the tops of the access boxes and the main distribution ducts and a cover plate is attached to enclose the main distribution ducts. The resulting floor structure has embedded therein parallel wiring raceways spaced across the floor with spaced accesses into each raceway and main distribution ducts interconnecting the parallel raceways. If desired, concrete floor slabs with trenches and metal covers may be prefabricated for later use in constructing buildings.
Description
This invention relates to electrical wiring ducts for a building and more particularly to an improved method and structure for forming electrical wiring ducts in a concrete building floor.
Buildings formed from concrete are often partially constructed before a final floor plan is selected. After the basic building structure is erected, such buildings are subdivided into spaces such as individual offices. Utility ducts for wiring and comfort conditioning are sometimes formed in poured concrete floors to facilitate supplying required utilities to each space into which the building is subsequently divided. One prior art method for forming utility ducts in a poured concrete floor is shown in United States Patent 3,093,933 which issued June 18, 1963 to Slingluff and in United States Patent 2,975,559 which issued March 21, 1961 to Hedgren. These patents disclose a building floor structure having a metallic cellular subflooring which forms parallel cells or conduits for carrying electrical cables and for air handling. Electrical ducts also are located immediately above and perpendicular to the cellular subflooring, These ducts are spaced across the subflooring to provide a desired 9pacing for electrical service connections. Access fitting~ are attached to the ducts at desired locations and the ducts are connected to the appropriate subfloor cells. A concrete floor is then poured over the cellular sub~ooring to embed the electrical ducts.
Wiring for power and ccmmunications is passed through the subflooring cells and the desired ducts for serving the floor area wherever such service is needed. ~y running electrical power and communications wiring through different subfloor ~k cells and through alternate ducts, the power wiring is shielded in accordance with some building codes and the communications wiring is isolated from the power wiring to minimize induced electrical noise. However, a building floor structure of this type is unnecessarily expensi~e because of the high cost for the cellular metallic subflooring and of the need for using separate metal channels for forming both power and communications ducts in the floor.
According to the present invention, an improved method is provided for forming wiring ducts or raceways in a concrete building floor. The method provides separate raceways for electrical power wiring and communications wiring with only the power raceways being completely shielded by metal.
In accordance with the present method, a building floor slab is poured from concrete or a similar hardenable material to a depth leaving room for a concrete topping or surface layer. At least one trench is formed in the upper surface of the floor slab before the material hardens. After the floor slab hardens sufficiently to maintain the shape of the trench, a metal cover plate is placed over each trench. A metal element is attached to the bottom of the cover plate to extend the length of the trench for dividing the trench into at least two and preferably three separate raceways. Adjustment means can be provided to compensate for irregularities in the depth of the trench. The metal element may be a U-sha~ed channel;
thus the center raceway, which is defined by the U-shaped metal channel and the metal cover plate, is completely shielded for carrying electrical power wiring while the remaining raceways on each side of the U-shaped channel are unshielded. These channels may carry communications wiring such as telephone wires, computer input, output and control wires, process control wires, intercom wires, etc. Access boxes are attached to the top of the trench cover plate for providing desired access to wires located in the raceways. Metal channels may also be placed perpendicular to and across all of the trenches for defining main power distribution ducts interconnecting the various parallel raceways. A topping Gr surface layer of concrete or other hardenable material is then poured over the previously poured concrete floor slab to extend flush with the top of the access boxes and the channels forming the power distribution ducts. Electrical wiring for servicing power and communication needs on the floor area may be completed by passing wires through the raceways between the main distribution channels and the access boxes and finally attaching a cover plate over the main distribution channels. Through this arrangement, power wiring for the entire system is shielded from the communications wiring to minimize electrical noise induced into the communications wiring. Furthermore, the cost of placing a metallic cellular subflooring in the building and separate metal ducts for defining both power and communications raceways is eliminated.
In a modification of the method of the present invention, a building is constructed with floors formed from prefabricated concrete slabs. Parallel trenches are cast in the slabs for forming wiring raceways or ducts. In some slabs, one-half of a trench is formed along a slab edge.
Other trenches are spaced interior from the slab edges and are provided with a cover plate having a U-shaped channel attached thereto for dividing the trench into at least two and preferably three separate wire raceways at the time the slab is prefabricated. The cover plate and u-shaped channel may be set in the trench while the concrete is partially hardened such that the U-shaped channel proiects into the concrete to compensate for irregularities in the trench depth and to completely isolate the wire raceways on either side of the V-shaped channel. The trenches formed along edges of the slabs are one-half the width of a finished trench in a building floor. Two slabs, each having one-half of a trench extending -along an edge are positioned with the trench h~lves - abutting when a building is constructed from the slabs.
Grouting is then poured into a joint formed between the slabs below the trench and a cover plate having an attached U-shaped channel is then positioned on the trench. Preferably, anchors spaced along the bottom of the U-shaped channel are set within the grouted joint between the two slabs. The wiring channels and the concrete floor in the building is then completed as in the previously descr-ibed embodiments of the invention.
Accordingly, it is a preferred object of the invention to provide an improved method for forming wiring ducts in a concrete building floor.
Another object of the invention is to provide a method for constructing parallel communications and power wiring ducts in a concrete floor with shielding for only the power wiring.
Other objects and advantages of the invention will become apparent from the following detailed description, with - reference being made to the accompanying drawings.
Fig. 1 is a fragmentary, sectioned perspective view of an improved concrete f~oor structure having wiring ducts formed therein in accordance with the present invention;
Fig. 2 is an enlarged fragmentary, sectioned perspective view of an inverted cover plate for dividing a trench formed in a concrete floor slab into three separate raceways, "- 1070510 Fig. 3 is an enlarged fragmentary, cross-sectional view taken along line 3-3 of Fig. l; -Fig. 4 is a fragmentary, sectioned perspective viewof an improved concrete floor structure having wiring ducts formed therein in accordance with a modified embodiment of the invention in whlch a portion of the floor is constructed from prefabricated concrete slabs;
Fig. 5 is an enlarged fragmentary, cross-sectional view taken along line 5-5 of Fig. 4; -Fig. 6 is an enlarged fragmentary,-cross-sectional view taken along line 6-6 sf Fig. 4; and ~ 8 ~`~
B Fig. 7 ~ *~ enlarged fragmentary cross-sectional viewSthrough ~ further modified concrete floor and wiring ducts formed in accordance with the present invention.
Turning now to the drawings and particularly to Fig. 1, a ~uilding floor structure 10 is shown embodying the structure and constructed by the method of the present invention. ~he floor structure 10 basically comprises a concrete floor slab 11 and a concrete surface or topping layer 12. Ducts or raceways are formed in the slab 11 and the surface layer 12 for supplying electrical power and communications to predetermin,ed spaced locations in the building in which the floor structure 10 is constructed.
Sufficient number of access points to the electrical ducts are provided in the surface layer 12 for supplying power and ,, communications requirements o~er the floor area regardless of the manner in which the floor area is subsequently subdivided.
When the concrete floor sla~ 11 is poured, a plurality of parallel trenches 13 are formed in an upper surface 14 of the slab 11. The trenches 13 may be formed by any suitable means, such as by placing wooden forms .
~not shown) in the upper surface 14 for forminq the trenches 13 and, after the concrete in the floor-slab-ll has at least partially hardened, removing such forms. After the sla~ 11 is poured and hardened sufficiently to maintain the shape of the trenches 13, at least some of-the trenches 13 are divided into at least two separate wiring ducts or raceways, with three raceways 15-17 shown in the drawinqs. The raceways 15-17 are formed by placing a cover plate 18 over each trench 13 to extend along the entire length of such trench. As best seen in Fig. 2, a generally U-shaped channel 19 is attached to the cover plate 18. The U-shaped channel 19 is attached to the cover plate 18 by any suitable means, as by spot welds 20 or by rivets, screws, bolts, etc. The channel 19 has sides 21 of a height corresponding to the depth of the trench 13 for d~viding the trench 13 into the separate ducts 15-17. It will be noted that the center duct 16 is defined by the U-shaped channels 19 and the cover plate 18, and, therefore, is completely shielded with metal. The ducts 15 and 17 are defined by the concrete walls of the trench 13 on two sides, by the channel sides 21 and by the cover plate 18. Because of the shielding, the duct 16 is particularly suitable for carrying power wires while the ducts 15 and 17 preferably are used for carrying communications wires such as telephone wires, local intercom wires, process control wires, and the ~i~e. ~y shielding the power wires in the duct 16, electrical noise induced into the communications wires is minimized.
Groups of three knockouts 22, 23 and 24 are spaced along each of the cover plates 18 for providiny access points ~0 through the cover plate 18 into the ducts 15-17, respectively. If, for example, the trenches 13 are located parallel to each other with a five foot center-to-center .
spacing and each group of knockouts 22-24 is placed at a five -foot spacing in the cover plates 18, then~the floor structure 10 will have access points into the ducts 15-17 in a grid pattern across the floor struc~ure 10 with a five foot - spacing. Such a spacing would normally be sufficient for providing adquate power and communications outlets in a building. The rectangular access boxes 25 may be attached to the cover plate 18 at each group of-knoc~outs 22-24.
The access boxes are shown as having a width which permits covering two adjacent ones of the knockouts, such as the knockouts 22 and 23 for providing access to the communications and power ducts 15 and 16 or the knockouts 23 and 24 for providing access to the power and communications ducts 16 and 17. In a preferred embodiment, the access boxes 25 are Ftaggered such that one box 25 on a cover plate 18 provides access to the ducts 15 and 16 through the knockouts 22 and 23 a~d the next access box 25 on the cover plate 18 provides access to the ducts 16 and 17 through the knockouts 23 and 24. However, it should be appreciated that the width of the access boxes 25 may be such that a box 25 provides access through only one knockout 22, 23 or 24 to one duct 15, 16 or 17, or that a box 25 provi~es access through all three knockouts 22-24 to the three ducts 15-17.
- In addition to the access boxes 25, three channels 26-28 are positioned to extend across and rest upon the cover p7ates 18. The channels 26-28 are preferably connected to each cover plate 18 to provide electrical ground continuity. The channels 26 and 2~ are generally C-shaped while the channel 27 spaced between the channels 26 and 28 is generally U-shaped. In addition, the channels 26-28 have the same height as the hei~ht of the access ~oxes 25. After the channels 26-28 are positioned and attached eo the cover plates 18, the concrete sur~ace or toppinq layer 12 is poured to form a top surface 12' which extends flush with the tops of the access boxes 25 and the channels 26-28.
After the surface layer 12 is poured and has hardened, communications and power wires are run through the raceways or ducts 15-17 and three main distribution raceways 29-31 formed between the channels 26-28 and within the channel 27. As previously indicated, the channels 26-28 extend across all of the cover plates 18 over the trenches 13.
Although not mandatory, it may be preferable to position the channels 26-28 perpendicular to the trenches 13. The main distribution raceway or duct 29 between the channels 26 and 27 communicates through an opening 32 in each cover plate 18 to the raceway 17. An opening 33 passes through the bottom of the U-shaped channel 27 and each cover plate 18 for communicating within the duct 30 formed ~y the channel 27 to each duct 16. Similarly, the duct or raceway 31 formed . between the channels 27 and 28 is connected through an opening 34 in each cover plate 18 to the duct or raceway 15.
Thus, communications wires are laid in the raceway or duct 29 and passed through the raceway 17 for communicating through the knockouts 24 and access boxes 25 to predetermined locations on the floor structure. Similarly, power wires are passed through the duct 30 formed by the channel 27, through the opening 33 and through the duct 16 for supplying power through the knockouts 23 and access boxes 25 to predetermined locations in the floor structure 10.
Communications wires may also be positioned in the duct or raceway 31 and passed through the openings 34 and the ducts or raceways 15. After the wires are positioned in the ducts or raceways 29-31 and 15-17, a cover plate 35 is positioned - - 10705~0 over the channels 26-28 and fastened to the channels 26 and 28 by means of suitable fasteners 36. The cover plates 35 and 18 and the channels 19 and 26-28 and the access boxes 25 ~ are all grounded for safety. Since the power wires in the duets 30 and 16 are completely surrounded by the channel 27 and its cover plate 35 and the channel 19 and its cover plate 18, the power wires are all eompletely shielded. The shielding protects~the communications wires from dama~e in the event of a short,eireuit in the power wires and also reduees electrieal noise which otherwise might be induced into the eommunieations eircuits.
Turning now to Fig. 3, a cross section is shown through the ducts 15-17 in one trench 13 and through an aeeess box 25. Although it may not always be required, it will ~e noted that fasteners 37 are shown attaching the eover plate 18 to the poured eoncrete slab 11. The fasteners 37 may be of a~y suitable desiqn, such as explosively driven nails. ~he primary pur,pose for the - , fasteners 37 is to maintain the eover plate 18 centered over the treneh 13 while the surface layer 12 is poured. It should be appreeiated that if the eover plate 18 is allowed to move while pouring the su~faee layer 12, the conerete or other hardenable material forming the surfaee layer 12 may flow into the trench 13. After the cover plate 18 is positioned over the treneh 13 to divide the treneh into the - three separate raceways or ducts 15-17, the aeeess ~ox 25 is attached to the eover plate 18 over either the knockouts 22 and 23 or the knoekouts 23 and 24. As shown in Fi~. 3, the knockouts 22 and 23 are removed leaving openings 22' and 23', respectively, through the eover plate 18 and into the duets 15 and 16. The aceess box 25 is then positioned over these openings 22' and 23'. Wires are positioned in the 10705~0 . - -- - ~ - - -ducts 15-17 at any suitable time during construction of the floor structure 10. For example, the wires may be run in the ducts lS-17 at the time the cover plate 18 is positioned - over the trench 13 and prior to pouring the surface layer 12. .
Or, wires may be pulled through the ducts 15-17 after the floor structure 10 is completed. A telephone wire 38 is shown exemplifying a typical wire located in the duct lS;
The telephone wire 38 passes through the cover plate opening 22' and is terminated at a connector 39. When telephone installation is completed, a serviceman connects a mating connector 40 attached to a line 41 which connects to a telephone (not shown) to the connector 39. The connectors 39 and 40 are positioned within the access box 25 to eliminate any obstacles on the top floor surface 12'.
An exemplary p~wer wire 42 is shown in the power duct 16.
The power conductor 42 passes through the cover plate opening 23' and is terminated at a standard power . -receptacle 43. An electrical appliance line cord 44 having a standard plug 45 may subsequently be passed through an opening 46 in the access box 25 and plugged into the receptacle 43. The opening 46 is sufficiently large as to permit users of the building to remove the plug 4S or to plug in other appliances.
As shown in Fig. 3, the access box 25 normally provides access to the power duct 16 and to one of the two communication ducts 15 or 17. It may be desirable, for example, to place only telephone wires in one of the communication ducts, duct lS shown, and to place other communication t~ires in the duct 17. ~urthermore, it also may be d2sirable to stagger the location o~ the access boxes 25 such that every other access box on a cover plate 18 provides access to the duct 15 while the remaining alternate - access boxes 25 provide access-to the duct 17. A-s represented -by the dashed lines 47, if access is subsequentiy desired into the duct 17 where such access is not provided by an access box 25, an opening above the knockout 24 may be formed -through the surface layer 12. Such an opening may be formed by any suitable means, as by drilling through the surface layer 12 or by providing a plug in the surface area 12 which is readily removable at a later date. -Of course, where access is desired into both of the communication ducts 15 and 17, the access box 25 may be constructed sufficiently large as to cover each of the three knockouts 22, 23 and 2~.
- Although Figs. 1-3 of the drawings specifically show a floor structure 10 hàving three parallel ducts formed in each trench 13, it will be appreciated that any other desired number of ducts may be formed in a floor trench.
For example, if only a single communication duct and a single power duct are desired, the trench 13 may be formed of a width sufficient to form only a single communication duct, duct 15 for example, and a single power duct 16. In such event, the U-shaped channel 19 would be located near one side of the cover plate 18 rather than centered as shown in the drawings. Where additional ducts are desired, it will also be appreciated that more than one U-shaped channel 19 may be attached to the bottom of the trench cover plate 18 for forming the desired number of ducts in the concrete floor slab 11.
Turning now to Fig. 4, a floor structure 50 is shown constructed in accordance with a modified embodiment of the method of the present invention. The floor structure 50 is constructed from a plurality of prefabricated floor slabs, of which two exemplary slabs 51 and 52 are shown in transverse section. The slabs 51 and 52 are Precast at a factory in standard widths such as eight feet or twelve -feet, and in various lengths for various size structures.
To reduce the weight of the slabs 51 and 52, voids 53 are formed to extend longitudinally through the slabs 51 and 52.
The strength of the slabs 51 and 52 is maintained through the use of reinforcement rods or bàrs 54. If desired, the bars 54 may prestress the slabs in a known manner. Wiring ducts 55 are formed in a trench between the abutting slabs 51 and 52 with one half 56 of the trench formed in the slab 51 and a second half 57 of the trench formed in the slab 52. A
grouted joint 58 extends between the slabs 51 and 52 and below the trench halves 56 and 57. A grouted joint 59 is also provided between the slab 51 and a next adjacent slab 60 and a grouted joint 61 is provided between the slab 52 and a next adjacent slab 62. Tr~nches for use in forming wiring ducts are formed above the grouted joints only when a desired location for wiring ducts or raceways is above such joints.
In addition to the trench defined by the trench halves 56 and 57 in the abutting portions of the slabs 51-and 52, wiring ducts or raceways 63 are formed in a trench 64 located interior from the edges of the slab Sl and wiring ducts 65 are located in a trench 66 l~cated interior from the edges of the slab 52. An exemplary access box 67 is shown for providing access to the wiring ducts SS which are located between the slabs 51 and 52 and an exemplary access box 68 is shown for providing access to the ducts 63 within the slab 51. The access boxes 67 and 68 are shown embedded within a topping layer 69 formed from concrete or any other suitable hardenable floor material.
Turning now to Fig. S, details are shown for the wiring ducts or raceways 63 spaced from the edges of and extending the longitudinal length of the floor slab Sl. A
generally U-shaped channel 70 divides th~ trench 64 into at least two and pref'erably three separate.wiring ducts or raceways.71, 72 and 73. The V-shaped channel 70 has upper flanges-74 which are welded,-bolted or otherwise attached to a cover plate iS which completely covers the trench 64.
Three sides of the duct 71 are defined by the U-shaped channel 70 and the fourth side is defined by the metal cover plate 63. As a consequence, the duct 71 is completely ' shielded to prevent passage of electromagnetic radiation from wires within the duct 71. ~he ducts 72 and 73 are located on opposite sides of the U-shaped channel 70 and are , defined on two sides'by the slab 51, on a third side by the U-shaped channel 70 and on a fourth side by the cover plate 75. Thus, the ducts 72 and 73 are not shielded.
Electrical power wiring about which substantial electromagnetic fields may be established is preferably located within the duct 71 while control and communications wiring is located within the ducts 72 and,73. In the event that only two ducts are required, one of the two ducts 72 and 73 may be eliminated either by shortening the size of the trench 64 or by moving the channel 70 to one side of the trench 64. On the other hand, if additional ducts are required, more than one U-shaped channel 70 may be attached to the cover plate 75.
The U-shaped channel 70 is provided with two ~ spaced paral~el sides 76 and 77 and a flat bottom 78'. The sides 76 and 77 extend below the bottom 78 to define lower fins or projections 79 on each side of the channel 70. The projections extend below the cover plate 75 and below the bottom a distance greater than the depth of the trench 64.
The cover plate 75 and attached U-shaped channel 70 are positioned over the trench 64 after the slab 51 is formed and 10705~0 the concrete has solidified only sufficiently to maintain ~ts shape. When the cover plate 75 is positioned over the trench 64, sufficient downward force is applied to force the projections 79 into the concrete at the bottom of t-he trench 64. By deforming the concrete with the projection 79, ~' the two ducts 72 and 73 are completely isolated, despite minor variations in the depth of the trench 64 along the length of the slab 51. If desired, the cover plate 75 can be anchored to the slab 51 with fasteners similar to the fasteners 37 in ~ig. 3 to retain the cover plate 75 in place-during shipment and installation of the slab 51. Thus, the slab 51 with the attached cover plate 75 and the U-shaped channel 70 dividing the trench 64 into the three separate ducts 71-73 are prefabricated in a factory.
Durin~ construction of a building from the slab 51, the slab 51 is positioned on suita~le supports which may be concrete walls or columns or steel beams. One or more of the access covers 68 are positioned over the trench 64 and-attached to the cover plate 75 to provide access into the ducts 71-73, as required. In the embodiment shown in Fig. 5, the access box 68 is positioned over the ducts 71 and 73.
The access box 68 has an inte~ior opening 80 which communicates through a hole 81 in the cover plate 75 leading into the duct 71 and through a hole 82 in the cover plate 75 leading into the duct 73. The holes 81 and 82 may be formed, for example, ~y removing knoc~outs or by a~y other conventional method. The final step in constructing the f~oor structure 50 is to pour the topping layer 6g over the slab 51 and flush with a removable cover 83 attached to the top of the access box 68.
Turning now to Fig. 6, a cross sectional view is shown through the wirinq ducts 55 and the access box 67 from Fig. 4.
--14-- r 070510 , . . .
The ducts 55 are defined by a U-shaped channel 86 and an attached cover plate 87 which enclose and separate the trench halves 56 and 57. The ducts 55 include a completely shielded duct 88 formed by the~U-shaped channel 86 and the cover plate 87, and unshielded duct 89 formed by the trench half 56 in the slab 51, one side of the U-shaped channel 86 and the cover plate 87 and an unshielded duct 90 formed by the trench half 57 in the slab 52, the duct 86 and the cover plate 87.
The ducts 88-90 are formed during the construction of a building including the floor structure 50. Initially, the slabs 51 and 52 are positioned on a suitable support structure (not shown). The grouted joint 58 is then formed by filling a groove 91 extending between the slabs 51 and 52 and below the trench halves 56 and 57 with a suitable ccncretious grouting material. Before such grouting material within the joint 58 has hardened, the cover plate 87 is positioned over the trench halves 56 and 57 with the U-shaped channel 86 abutting the grouted joint 58.
Preferably, a plurality of studs 92 having ir~egular surfaces or a plurality of other suitable anchors are attached to the bottom of the U-shaped channel 86 at predetermined spacings along its length. The studs or other suitable anchors 92 are pressed into the grouted joint 58 to securely anchor in place the cover plate 87 and attached U-shaped channel 86.
The grouted joint 58 is also deformed sufficiently by the - U-shaped channel 86 to assure that the ducts 89 and 90 are completely isolated from each other. After the U-shaped channel 86 and cover plate 87 are positioned over the trench halves 56 and 57 and the grouted joint 58, the floor structure 50 is completed in a manner similar to that described for Figs. 1-3. The access box 67 and other access boxes, as needed, are attached to the cover plate 87 either - - ~o705~
- over the channels 88 and 90 or over ~he channels B8 and 89 or - over all three channels 88-90, as required and at any desired location. The topping layer 69 is then applied to complete the floor. The topping layer 69 is of a thickness ~ufficient to extend flush with a removable cover 93 for the access box 67. After the floor structure 50 is completed, the space above the floor structure 50 may be divided into - rooms, as desired. A typical partition 95 is shown in dashed lines in Fig. 6 located adjacent the access box cover 93. At the same time the building is partitioned into rooms, or if necessary at a subsequent date, suitable electrical power wiring, control wiring, communications wirin~ and the like is run through the ducts 8B-90 to supply the needs of the space above the floor structure 50.
In the embodiment shown in Fig. 5, projections 79 at the bottom of the U-shaped channel 70 were forced into the slab 51 before the concretious material forming the slab 51 had completely hardened. The function of the projections 79 was to assure that the ducts 72 and 73 were completely isolated by the U-shaped channel 70.
Turning now to Fig. 7, a different method is shown for assuring that two ducts 97 and 98 spaced on either side of a U-shaped channel 99 are completely isolated, despite variations in the depth along the length of a trench 100 in which the U-shaped channel 99 is located. The U-shaped - channel 99 includes two upper side flanges 101 and 102 which are welded or otherwise attached to a cover plate 103. A
lower U-shaped channel member 104 is positioned between the flan~es 101 and 102. The U-shaped member 1~4 includes sides 105 and 106 which are firmly held between the flanges 101 and 102, respectively, by spring tension. When the U-shaped chanr,el 99 and cover plate 103 are positioned '1070510- - -.
~ within the trench 100, the U-shaped channel 104 is forced upwardly between the flanges 101 and-102 as a bottom 107 of the channel 104 contacts the trench 100. Through this method, the lower U-shaped member 104-contacts the trench 100 to completely isolate the ducts 97 and 98, despite variations in the depth of the trench 100 along its length.
Turning to Fig. 8, still another structure and method are shown for compensating for variations in the -depth of a trench llO when a floor structure is constructed in accordance with the present invention. In this emobdiment, a U-shaped channel 111 is not attached to a cover plate 112, as in the previously described embodiments. The trench 110 is formed within a concrete slab 113 having an upper surface 114. The U-shaped channel 111 includes a lower ~U-shaped member 115 having spaced sides 116 and 117. 8O1ts 118 pass through vertical slots within a flange 119 and attach such flange 119 to the side 116. Similarly, others of the bolts 118 pass through vertical slots in a flange 120 and attach such flange 120 to the side 117. ~he bolts 118 are threaded lnto the sides 116 and 117 and are sufficiently short as not to project appreciably into the duct 122.
During construction of ducts 121-123 in the trench 110, the U-shaped channel 111 is positioned in the center of the trench 110. A workman then positions a straightedge on the upper surfaces ?14 of the slab 113 to span the trench 110 - and to extend over the flanges 119 and 120 of the U--shaped channe} ~11. The flanges 119 and 120 are then moved into contact with such straightedge so they are flush with the upper surfaces 114. ~he cover plate 112 is then positioned over the trench 110 and the U-shaped channel 11, access boxes are installed as necessary, and a topping layer 124 is applied to complete the floor structure. Seals 125 are - 1~705~
located between the flanges 119 and 120 and the. cover -plate 112. The seals 125 may consist of resilient members formed from a suitable synthetic resinous material or they may consist of a suitable adhesive which bonds the flanges 119 and 120 to the cover plate 112.
Although several different methods have been described for adjusting or compensating for variations in the depth of a trench when such trench is divided into a plurality of ducts, it will be appreciated that other methods may also be used without departing from the invention. For example, the U-shaped channel member may fit within a recess in the bottom of the trench formed in the concrete ~loor slab. Before positioning the U-shaped channel member within the recess, a suitable hardenable material such as a synthetic resinous material or a concretious material may be positioned within the recess to bond the U-shaped channel member to the floor slab and also to isolate ducts formed on either side of the V-shaped member.
It will be appreciated that various other modifications and changes may be made in the above-described preferred embodiments of the invention without departing from the spirit and the scope of the following claims.
Buildings formed from concrete are often partially constructed before a final floor plan is selected. After the basic building structure is erected, such buildings are subdivided into spaces such as individual offices. Utility ducts for wiring and comfort conditioning are sometimes formed in poured concrete floors to facilitate supplying required utilities to each space into which the building is subsequently divided. One prior art method for forming utility ducts in a poured concrete floor is shown in United States Patent 3,093,933 which issued June 18, 1963 to Slingluff and in United States Patent 2,975,559 which issued March 21, 1961 to Hedgren. These patents disclose a building floor structure having a metallic cellular subflooring which forms parallel cells or conduits for carrying electrical cables and for air handling. Electrical ducts also are located immediately above and perpendicular to the cellular subflooring, These ducts are spaced across the subflooring to provide a desired 9pacing for electrical service connections. Access fitting~ are attached to the ducts at desired locations and the ducts are connected to the appropriate subfloor cells. A concrete floor is then poured over the cellular sub~ooring to embed the electrical ducts.
Wiring for power and ccmmunications is passed through the subflooring cells and the desired ducts for serving the floor area wherever such service is needed. ~y running electrical power and communications wiring through different subfloor ~k cells and through alternate ducts, the power wiring is shielded in accordance with some building codes and the communications wiring is isolated from the power wiring to minimize induced electrical noise. However, a building floor structure of this type is unnecessarily expensi~e because of the high cost for the cellular metallic subflooring and of the need for using separate metal channels for forming both power and communications ducts in the floor.
According to the present invention, an improved method is provided for forming wiring ducts or raceways in a concrete building floor. The method provides separate raceways for electrical power wiring and communications wiring with only the power raceways being completely shielded by metal.
In accordance with the present method, a building floor slab is poured from concrete or a similar hardenable material to a depth leaving room for a concrete topping or surface layer. At least one trench is formed in the upper surface of the floor slab before the material hardens. After the floor slab hardens sufficiently to maintain the shape of the trench, a metal cover plate is placed over each trench. A metal element is attached to the bottom of the cover plate to extend the length of the trench for dividing the trench into at least two and preferably three separate raceways. Adjustment means can be provided to compensate for irregularities in the depth of the trench. The metal element may be a U-sha~ed channel;
thus the center raceway, which is defined by the U-shaped metal channel and the metal cover plate, is completely shielded for carrying electrical power wiring while the remaining raceways on each side of the U-shaped channel are unshielded. These channels may carry communications wiring such as telephone wires, computer input, output and control wires, process control wires, intercom wires, etc. Access boxes are attached to the top of the trench cover plate for providing desired access to wires located in the raceways. Metal channels may also be placed perpendicular to and across all of the trenches for defining main power distribution ducts interconnecting the various parallel raceways. A topping Gr surface layer of concrete or other hardenable material is then poured over the previously poured concrete floor slab to extend flush with the top of the access boxes and the channels forming the power distribution ducts. Electrical wiring for servicing power and communication needs on the floor area may be completed by passing wires through the raceways between the main distribution channels and the access boxes and finally attaching a cover plate over the main distribution channels. Through this arrangement, power wiring for the entire system is shielded from the communications wiring to minimize electrical noise induced into the communications wiring. Furthermore, the cost of placing a metallic cellular subflooring in the building and separate metal ducts for defining both power and communications raceways is eliminated.
In a modification of the method of the present invention, a building is constructed with floors formed from prefabricated concrete slabs. Parallel trenches are cast in the slabs for forming wiring raceways or ducts. In some slabs, one-half of a trench is formed along a slab edge.
Other trenches are spaced interior from the slab edges and are provided with a cover plate having a U-shaped channel attached thereto for dividing the trench into at least two and preferably three separate wire raceways at the time the slab is prefabricated. The cover plate and u-shaped channel may be set in the trench while the concrete is partially hardened such that the U-shaped channel proiects into the concrete to compensate for irregularities in the trench depth and to completely isolate the wire raceways on either side of the V-shaped channel. The trenches formed along edges of the slabs are one-half the width of a finished trench in a building floor. Two slabs, each having one-half of a trench extending -along an edge are positioned with the trench h~lves - abutting when a building is constructed from the slabs.
Grouting is then poured into a joint formed between the slabs below the trench and a cover plate having an attached U-shaped channel is then positioned on the trench. Preferably, anchors spaced along the bottom of the U-shaped channel are set within the grouted joint between the two slabs. The wiring channels and the concrete floor in the building is then completed as in the previously descr-ibed embodiments of the invention.
Accordingly, it is a preferred object of the invention to provide an improved method for forming wiring ducts in a concrete building floor.
Another object of the invention is to provide a method for constructing parallel communications and power wiring ducts in a concrete floor with shielding for only the power wiring.
Other objects and advantages of the invention will become apparent from the following detailed description, with - reference being made to the accompanying drawings.
Fig. 1 is a fragmentary, sectioned perspective view of an improved concrete f~oor structure having wiring ducts formed therein in accordance with the present invention;
Fig. 2 is an enlarged fragmentary, sectioned perspective view of an inverted cover plate for dividing a trench formed in a concrete floor slab into three separate raceways, "- 1070510 Fig. 3 is an enlarged fragmentary, cross-sectional view taken along line 3-3 of Fig. l; -Fig. 4 is a fragmentary, sectioned perspective viewof an improved concrete floor structure having wiring ducts formed therein in accordance with a modified embodiment of the invention in whlch a portion of the floor is constructed from prefabricated concrete slabs;
Fig. 5 is an enlarged fragmentary, cross-sectional view taken along line 5-5 of Fig. 4; -Fig. 6 is an enlarged fragmentary,-cross-sectional view taken along line 6-6 sf Fig. 4; and ~ 8 ~`~
B Fig. 7 ~ *~ enlarged fragmentary cross-sectional viewSthrough ~ further modified concrete floor and wiring ducts formed in accordance with the present invention.
Turning now to the drawings and particularly to Fig. 1, a ~uilding floor structure 10 is shown embodying the structure and constructed by the method of the present invention. ~he floor structure 10 basically comprises a concrete floor slab 11 and a concrete surface or topping layer 12. Ducts or raceways are formed in the slab 11 and the surface layer 12 for supplying electrical power and communications to predetermin,ed spaced locations in the building in which the floor structure 10 is constructed.
Sufficient number of access points to the electrical ducts are provided in the surface layer 12 for supplying power and ,, communications requirements o~er the floor area regardless of the manner in which the floor area is subsequently subdivided.
When the concrete floor sla~ 11 is poured, a plurality of parallel trenches 13 are formed in an upper surface 14 of the slab 11. The trenches 13 may be formed by any suitable means, such as by placing wooden forms .
~not shown) in the upper surface 14 for forminq the trenches 13 and, after the concrete in the floor-slab-ll has at least partially hardened, removing such forms. After the sla~ 11 is poured and hardened sufficiently to maintain the shape of the trenches 13, at least some of-the trenches 13 are divided into at least two separate wiring ducts or raceways, with three raceways 15-17 shown in the drawinqs. The raceways 15-17 are formed by placing a cover plate 18 over each trench 13 to extend along the entire length of such trench. As best seen in Fig. 2, a generally U-shaped channel 19 is attached to the cover plate 18. The U-shaped channel 19 is attached to the cover plate 18 by any suitable means, as by spot welds 20 or by rivets, screws, bolts, etc. The channel 19 has sides 21 of a height corresponding to the depth of the trench 13 for d~viding the trench 13 into the separate ducts 15-17. It will be noted that the center duct 16 is defined by the U-shaped channels 19 and the cover plate 18, and, therefore, is completely shielded with metal. The ducts 15 and 17 are defined by the concrete walls of the trench 13 on two sides, by the channel sides 21 and by the cover plate 18. Because of the shielding, the duct 16 is particularly suitable for carrying power wires while the ducts 15 and 17 preferably are used for carrying communications wires such as telephone wires, local intercom wires, process control wires, and the ~i~e. ~y shielding the power wires in the duct 16, electrical noise induced into the communications wires is minimized.
Groups of three knockouts 22, 23 and 24 are spaced along each of the cover plates 18 for providiny access points ~0 through the cover plate 18 into the ducts 15-17, respectively. If, for example, the trenches 13 are located parallel to each other with a five foot center-to-center .
spacing and each group of knockouts 22-24 is placed at a five -foot spacing in the cover plates 18, then~the floor structure 10 will have access points into the ducts 15-17 in a grid pattern across the floor struc~ure 10 with a five foot - spacing. Such a spacing would normally be sufficient for providing adquate power and communications outlets in a building. The rectangular access boxes 25 may be attached to the cover plate 18 at each group of-knoc~outs 22-24.
The access boxes are shown as having a width which permits covering two adjacent ones of the knockouts, such as the knockouts 22 and 23 for providing access to the communications and power ducts 15 and 16 or the knockouts 23 and 24 for providing access to the power and communications ducts 16 and 17. In a preferred embodiment, the access boxes 25 are Ftaggered such that one box 25 on a cover plate 18 provides access to the ducts 15 and 16 through the knockouts 22 and 23 a~d the next access box 25 on the cover plate 18 provides access to the ducts 16 and 17 through the knockouts 23 and 24. However, it should be appreciated that the width of the access boxes 25 may be such that a box 25 provides access through only one knockout 22, 23 or 24 to one duct 15, 16 or 17, or that a box 25 provi~es access through all three knockouts 22-24 to the three ducts 15-17.
- In addition to the access boxes 25, three channels 26-28 are positioned to extend across and rest upon the cover p7ates 18. The channels 26-28 are preferably connected to each cover plate 18 to provide electrical ground continuity. The channels 26 and 2~ are generally C-shaped while the channel 27 spaced between the channels 26 and 28 is generally U-shaped. In addition, the channels 26-28 have the same height as the hei~ht of the access ~oxes 25. After the channels 26-28 are positioned and attached eo the cover plates 18, the concrete sur~ace or toppinq layer 12 is poured to form a top surface 12' which extends flush with the tops of the access boxes 25 and the channels 26-28.
After the surface layer 12 is poured and has hardened, communications and power wires are run through the raceways or ducts 15-17 and three main distribution raceways 29-31 formed between the channels 26-28 and within the channel 27. As previously indicated, the channels 26-28 extend across all of the cover plates 18 over the trenches 13.
Although not mandatory, it may be preferable to position the channels 26-28 perpendicular to the trenches 13. The main distribution raceway or duct 29 between the channels 26 and 27 communicates through an opening 32 in each cover plate 18 to the raceway 17. An opening 33 passes through the bottom of the U-shaped channel 27 and each cover plate 18 for communicating within the duct 30 formed ~y the channel 27 to each duct 16. Similarly, the duct or raceway 31 formed . between the channels 27 and 28 is connected through an opening 34 in each cover plate 18 to the duct or raceway 15.
Thus, communications wires are laid in the raceway or duct 29 and passed through the raceway 17 for communicating through the knockouts 24 and access boxes 25 to predetermined locations on the floor structure. Similarly, power wires are passed through the duct 30 formed by the channel 27, through the opening 33 and through the duct 16 for supplying power through the knockouts 23 and access boxes 25 to predetermined locations in the floor structure 10.
Communications wires may also be positioned in the duct or raceway 31 and passed through the openings 34 and the ducts or raceways 15. After the wires are positioned in the ducts or raceways 29-31 and 15-17, a cover plate 35 is positioned - - 10705~0 over the channels 26-28 and fastened to the channels 26 and 28 by means of suitable fasteners 36. The cover plates 35 and 18 and the channels 19 and 26-28 and the access boxes 25 ~ are all grounded for safety. Since the power wires in the duets 30 and 16 are completely surrounded by the channel 27 and its cover plate 35 and the channel 19 and its cover plate 18, the power wires are all eompletely shielded. The shielding protects~the communications wires from dama~e in the event of a short,eireuit in the power wires and also reduees electrieal noise which otherwise might be induced into the eommunieations eircuits.
Turning now to Fig. 3, a cross section is shown through the ducts 15-17 in one trench 13 and through an aeeess box 25. Although it may not always be required, it will ~e noted that fasteners 37 are shown attaching the eover plate 18 to the poured eoncrete slab 11. The fasteners 37 may be of a~y suitable desiqn, such as explosively driven nails. ~he primary pur,pose for the - , fasteners 37 is to maintain the eover plate 18 centered over the treneh 13 while the surface layer 12 is poured. It should be appreeiated that if the eover plate 18 is allowed to move while pouring the su~faee layer 12, the conerete or other hardenable material forming the surfaee layer 12 may flow into the trench 13. After the cover plate 18 is positioned over the treneh 13 to divide the treneh into the - three separate raceways or ducts 15-17, the aeeess ~ox 25 is attached to the eover plate 18 over either the knockouts 22 and 23 or the knoekouts 23 and 24. As shown in Fi~. 3, the knockouts 22 and 23 are removed leaving openings 22' and 23', respectively, through the eover plate 18 and into the duets 15 and 16. The aceess box 25 is then positioned over these openings 22' and 23'. Wires are positioned in the 10705~0 . - -- - ~ - - -ducts 15-17 at any suitable time during construction of the floor structure 10. For example, the wires may be run in the ducts lS-17 at the time the cover plate 18 is positioned - over the trench 13 and prior to pouring the surface layer 12. .
Or, wires may be pulled through the ducts 15-17 after the floor structure 10 is completed. A telephone wire 38 is shown exemplifying a typical wire located in the duct lS;
The telephone wire 38 passes through the cover plate opening 22' and is terminated at a connector 39. When telephone installation is completed, a serviceman connects a mating connector 40 attached to a line 41 which connects to a telephone (not shown) to the connector 39. The connectors 39 and 40 are positioned within the access box 25 to eliminate any obstacles on the top floor surface 12'.
An exemplary p~wer wire 42 is shown in the power duct 16.
The power conductor 42 passes through the cover plate opening 23' and is terminated at a standard power . -receptacle 43. An electrical appliance line cord 44 having a standard plug 45 may subsequently be passed through an opening 46 in the access box 25 and plugged into the receptacle 43. The opening 46 is sufficiently large as to permit users of the building to remove the plug 4S or to plug in other appliances.
As shown in Fig. 3, the access box 25 normally provides access to the power duct 16 and to one of the two communication ducts 15 or 17. It may be desirable, for example, to place only telephone wires in one of the communication ducts, duct lS shown, and to place other communication t~ires in the duct 17. ~urthermore, it also may be d2sirable to stagger the location o~ the access boxes 25 such that every other access box on a cover plate 18 provides access to the duct 15 while the remaining alternate - access boxes 25 provide access-to the duct 17. A-s represented -by the dashed lines 47, if access is subsequentiy desired into the duct 17 where such access is not provided by an access box 25, an opening above the knockout 24 may be formed -through the surface layer 12. Such an opening may be formed by any suitable means, as by drilling through the surface layer 12 or by providing a plug in the surface area 12 which is readily removable at a later date. -Of course, where access is desired into both of the communication ducts 15 and 17, the access box 25 may be constructed sufficiently large as to cover each of the three knockouts 22, 23 and 2~.
- Although Figs. 1-3 of the drawings specifically show a floor structure 10 hàving three parallel ducts formed in each trench 13, it will be appreciated that any other desired number of ducts may be formed in a floor trench.
For example, if only a single communication duct and a single power duct are desired, the trench 13 may be formed of a width sufficient to form only a single communication duct, duct 15 for example, and a single power duct 16. In such event, the U-shaped channel 19 would be located near one side of the cover plate 18 rather than centered as shown in the drawings. Where additional ducts are desired, it will also be appreciated that more than one U-shaped channel 19 may be attached to the bottom of the trench cover plate 18 for forming the desired number of ducts in the concrete floor slab 11.
Turning now to Fig. 4, a floor structure 50 is shown constructed in accordance with a modified embodiment of the method of the present invention. The floor structure 50 is constructed from a plurality of prefabricated floor slabs, of which two exemplary slabs 51 and 52 are shown in transverse section. The slabs 51 and 52 are Precast at a factory in standard widths such as eight feet or twelve -feet, and in various lengths for various size structures.
To reduce the weight of the slabs 51 and 52, voids 53 are formed to extend longitudinally through the slabs 51 and 52.
The strength of the slabs 51 and 52 is maintained through the use of reinforcement rods or bàrs 54. If desired, the bars 54 may prestress the slabs in a known manner. Wiring ducts 55 are formed in a trench between the abutting slabs 51 and 52 with one half 56 of the trench formed in the slab 51 and a second half 57 of the trench formed in the slab 52. A
grouted joint 58 extends between the slabs 51 and 52 and below the trench halves 56 and 57. A grouted joint 59 is also provided between the slab 51 and a next adjacent slab 60 and a grouted joint 61 is provided between the slab 52 and a next adjacent slab 62. Tr~nches for use in forming wiring ducts are formed above the grouted joints only when a desired location for wiring ducts or raceways is above such joints.
In addition to the trench defined by the trench halves 56 and 57 in the abutting portions of the slabs 51-and 52, wiring ducts or raceways 63 are formed in a trench 64 located interior from the edges of the slab Sl and wiring ducts 65 are located in a trench 66 l~cated interior from the edges of the slab 52. An exemplary access box 67 is shown for providing access to the wiring ducts SS which are located between the slabs 51 and 52 and an exemplary access box 68 is shown for providing access to the ducts 63 within the slab 51. The access boxes 67 and 68 are shown embedded within a topping layer 69 formed from concrete or any other suitable hardenable floor material.
Turning now to Fig. S, details are shown for the wiring ducts or raceways 63 spaced from the edges of and extending the longitudinal length of the floor slab Sl. A
generally U-shaped channel 70 divides th~ trench 64 into at least two and pref'erably three separate.wiring ducts or raceways.71, 72 and 73. The V-shaped channel 70 has upper flanges-74 which are welded,-bolted or otherwise attached to a cover plate iS which completely covers the trench 64.
Three sides of the duct 71 are defined by the U-shaped channel 70 and the fourth side is defined by the metal cover plate 63. As a consequence, the duct 71 is completely ' shielded to prevent passage of electromagnetic radiation from wires within the duct 71. ~he ducts 72 and 73 are located on opposite sides of the U-shaped channel 70 and are , defined on two sides'by the slab 51, on a third side by the U-shaped channel 70 and on a fourth side by the cover plate 75. Thus, the ducts 72 and 73 are not shielded.
Electrical power wiring about which substantial electromagnetic fields may be established is preferably located within the duct 71 while control and communications wiring is located within the ducts 72 and,73. In the event that only two ducts are required, one of the two ducts 72 and 73 may be eliminated either by shortening the size of the trench 64 or by moving the channel 70 to one side of the trench 64. On the other hand, if additional ducts are required, more than one U-shaped channel 70 may be attached to the cover plate 75.
The U-shaped channel 70 is provided with two ~ spaced paral~el sides 76 and 77 and a flat bottom 78'. The sides 76 and 77 extend below the bottom 78 to define lower fins or projections 79 on each side of the channel 70. The projections extend below the cover plate 75 and below the bottom a distance greater than the depth of the trench 64.
The cover plate 75 and attached U-shaped channel 70 are positioned over the trench 64 after the slab 51 is formed and 10705~0 the concrete has solidified only sufficiently to maintain ~ts shape. When the cover plate 75 is positioned over the trench 64, sufficient downward force is applied to force the projections 79 into the concrete at the bottom of t-he trench 64. By deforming the concrete with the projection 79, ~' the two ducts 72 and 73 are completely isolated, despite minor variations in the depth of the trench 64 along the length of the slab 51. If desired, the cover plate 75 can be anchored to the slab 51 with fasteners similar to the fasteners 37 in ~ig. 3 to retain the cover plate 75 in place-during shipment and installation of the slab 51. Thus, the slab 51 with the attached cover plate 75 and the U-shaped channel 70 dividing the trench 64 into the three separate ducts 71-73 are prefabricated in a factory.
Durin~ construction of a building from the slab 51, the slab 51 is positioned on suita~le supports which may be concrete walls or columns or steel beams. One or more of the access covers 68 are positioned over the trench 64 and-attached to the cover plate 75 to provide access into the ducts 71-73, as required. In the embodiment shown in Fig. 5, the access box 68 is positioned over the ducts 71 and 73.
The access box 68 has an inte~ior opening 80 which communicates through a hole 81 in the cover plate 75 leading into the duct 71 and through a hole 82 in the cover plate 75 leading into the duct 73. The holes 81 and 82 may be formed, for example, ~y removing knoc~outs or by a~y other conventional method. The final step in constructing the f~oor structure 50 is to pour the topping layer 6g over the slab 51 and flush with a removable cover 83 attached to the top of the access box 68.
Turning now to Fig. 6, a cross sectional view is shown through the wirinq ducts 55 and the access box 67 from Fig. 4.
--14-- r 070510 , . . .
The ducts 55 are defined by a U-shaped channel 86 and an attached cover plate 87 which enclose and separate the trench halves 56 and 57. The ducts 55 include a completely shielded duct 88 formed by the~U-shaped channel 86 and the cover plate 87, and unshielded duct 89 formed by the trench half 56 in the slab 51, one side of the U-shaped channel 86 and the cover plate 87 and an unshielded duct 90 formed by the trench half 57 in the slab 52, the duct 86 and the cover plate 87.
The ducts 88-90 are formed during the construction of a building including the floor structure 50. Initially, the slabs 51 and 52 are positioned on a suitable support structure (not shown). The grouted joint 58 is then formed by filling a groove 91 extending between the slabs 51 and 52 and below the trench halves 56 and 57 with a suitable ccncretious grouting material. Before such grouting material within the joint 58 has hardened, the cover plate 87 is positioned over the trench halves 56 and 57 with the U-shaped channel 86 abutting the grouted joint 58.
Preferably, a plurality of studs 92 having ir~egular surfaces or a plurality of other suitable anchors are attached to the bottom of the U-shaped channel 86 at predetermined spacings along its length. The studs or other suitable anchors 92 are pressed into the grouted joint 58 to securely anchor in place the cover plate 87 and attached U-shaped channel 86.
The grouted joint 58 is also deformed sufficiently by the - U-shaped channel 86 to assure that the ducts 89 and 90 are completely isolated from each other. After the U-shaped channel 86 and cover plate 87 are positioned over the trench halves 56 and 57 and the grouted joint 58, the floor structure 50 is completed in a manner similar to that described for Figs. 1-3. The access box 67 and other access boxes, as needed, are attached to the cover plate 87 either - - ~o705~
- over the channels 88 and 90 or over ~he channels B8 and 89 or - over all three channels 88-90, as required and at any desired location. The topping layer 69 is then applied to complete the floor. The topping layer 69 is of a thickness ~ufficient to extend flush with a removable cover 93 for the access box 67. After the floor structure 50 is completed, the space above the floor structure 50 may be divided into - rooms, as desired. A typical partition 95 is shown in dashed lines in Fig. 6 located adjacent the access box cover 93. At the same time the building is partitioned into rooms, or if necessary at a subsequent date, suitable electrical power wiring, control wiring, communications wirin~ and the like is run through the ducts 8B-90 to supply the needs of the space above the floor structure 50.
In the embodiment shown in Fig. 5, projections 79 at the bottom of the U-shaped channel 70 were forced into the slab 51 before the concretious material forming the slab 51 had completely hardened. The function of the projections 79 was to assure that the ducts 72 and 73 were completely isolated by the U-shaped channel 70.
Turning now to Fig. 7, a different method is shown for assuring that two ducts 97 and 98 spaced on either side of a U-shaped channel 99 are completely isolated, despite variations in the depth along the length of a trench 100 in which the U-shaped channel 99 is located. The U-shaped - channel 99 includes two upper side flanges 101 and 102 which are welded or otherwise attached to a cover plate 103. A
lower U-shaped channel member 104 is positioned between the flan~es 101 and 102. The U-shaped member 1~4 includes sides 105 and 106 which are firmly held between the flanges 101 and 102, respectively, by spring tension. When the U-shaped chanr,el 99 and cover plate 103 are positioned '1070510- - -.
~ within the trench 100, the U-shaped channel 104 is forced upwardly between the flanges 101 and-102 as a bottom 107 of the channel 104 contacts the trench 100. Through this method, the lower U-shaped member 104-contacts the trench 100 to completely isolate the ducts 97 and 98, despite variations in the depth of the trench 100 along its length.
Turning to Fig. 8, still another structure and method are shown for compensating for variations in the -depth of a trench llO when a floor structure is constructed in accordance with the present invention. In this emobdiment, a U-shaped channel 111 is not attached to a cover plate 112, as in the previously described embodiments. The trench 110 is formed within a concrete slab 113 having an upper surface 114. The U-shaped channel 111 includes a lower ~U-shaped member 115 having spaced sides 116 and 117. 8O1ts 118 pass through vertical slots within a flange 119 and attach such flange 119 to the side 116. Similarly, others of the bolts 118 pass through vertical slots in a flange 120 and attach such flange 120 to the side 117. ~he bolts 118 are threaded lnto the sides 116 and 117 and are sufficiently short as not to project appreciably into the duct 122.
During construction of ducts 121-123 in the trench 110, the U-shaped channel 111 is positioned in the center of the trench 110. A workman then positions a straightedge on the upper surfaces ?14 of the slab 113 to span the trench 110 - and to extend over the flanges 119 and 120 of the U--shaped channe} ~11. The flanges 119 and 120 are then moved into contact with such straightedge so they are flush with the upper surfaces 114. ~he cover plate 112 is then positioned over the trench 110 and the U-shaped channel 11, access boxes are installed as necessary, and a topping layer 124 is applied to complete the floor structure. Seals 125 are - 1~705~
located between the flanges 119 and 120 and the. cover -plate 112. The seals 125 may consist of resilient members formed from a suitable synthetic resinous material or they may consist of a suitable adhesive which bonds the flanges 119 and 120 to the cover plate 112.
Although several different methods have been described for adjusting or compensating for variations in the depth of a trench when such trench is divided into a plurality of ducts, it will be appreciated that other methods may also be used without departing from the invention. For example, the U-shaped channel member may fit within a recess in the bottom of the trench formed in the concrete ~loor slab. Before positioning the U-shaped channel member within the recess, a suitable hardenable material such as a synthetic resinous material or a concretious material may be positioned within the recess to bond the U-shaped channel member to the floor slab and also to isolate ducts formed on either side of the V-shaped member.
It will be appreciated that various other modifications and changes may be made in the above-described preferred embodiments of the invention without departing from the spirit and the scope of the following claims.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for forming electrical wiring ducts in a building floor comprising the steps of: pouring a floor slab from a hardenable material;
forming at least one trench in an upper surface of said poured floor slab before such material hardens; after such material hardens, placing a metal cover plate having a metal element attached thereto over said trench with said element dividing said trench into at least two parallel ducts with the ducts defined by said cover plate and said element; selectively attaching access boxes to the upper surface of said cover plate for providing access into said ducts, and pouring a surface layer of hardenable material over said slab and said cover plate.
forming at least one trench in an upper surface of said poured floor slab before such material hardens; after such material hardens, placing a metal cover plate having a metal element attached thereto over said trench with said element dividing said trench into at least two parallel ducts with the ducts defined by said cover plate and said element; selectively attaching access boxes to the upper surface of said cover plate for providing access into said ducts, and pouring a surface layer of hardenable material over said slab and said cover plate.
2. A method for forming a plurality of electrical wiring ducts in a building floor, as set forth in claim 1, said element comprising a U-shaped channel, wherein said cover plate is placed over said trench such that said U-shaped channel divides said trench into three parallel ducts with the center one of said three ducts defined by said cover plate and said U-shaped charnel.
3. A method for forming a plurality of electrical wiring ducts in a building floor, as set forth in claim 2, wherein a plurality of parallel trenches are formed in the upper surface of said poured slab and a cover plate is placed over each trench, at least some of such cover plates having a U-shaped channel attached thereto which divides the trench covered by such plates into at least two parallel ducts, and further including the step of placing a plurality of parallel channel members across all of said cover plates prior to pouring said surface layer for forming main distribution ducts interconnecting corresponding ducts in each of said trenches, pouring said surface layer to-a thickness substantially flush with the tops of said access boxes and said channel members, and attaching a cover plate to said channel members for enclosing said main distribution ducts.
4. A method for forming a plurality of electrical wiring ducts in a building floor, as set forth in claim 2, wherein said step of placing said metal cover plate and attached U-shaped channel over said trench includes the step of adjusting said U-shaped channel to contact said trench along the length of said trench whereby ducts on either side of said U-shaped channel are isolated.
5. A method for forming a plurality of electrical wiring ducts in a building floor slab comprising the steps of:
forming said floor slab from a hardenable material; forming at least one trench in an upper surface of said floor slab before such material hardens; after such material at least partially hardens, placing a metal cover plate having a U-shaped channel attached thereto over said trench with said channel dividing said trench into at least two parallel ducts with one duct defined by said cover plate and said U-shaped channel and at least one other duct defined by said cover plate, said U-shaped channel and said trench.
forming said floor slab from a hardenable material; forming at least one trench in an upper surface of said floor slab before such material hardens; after such material at least partially hardens, placing a metal cover plate having a U-shaped channel attached thereto over said trench with said channel dividing said trench into at least two parallel ducts with one duct defined by said cover plate and said U-shaped channel and at least one other duct defined by said cover plate, said U-shaped channel and said trench.
6. A method for forming a plurality of electrical wiring ducts in a building floor slab, as set forth in claim 5, wherein said metal cover is placed over said trench when such material has hardened only sufficiently to maintain the shape of said trench, and wherein said U-shaped channel is forced against and deforms a bottom of said trench when said cover is placed over said trench whereby ducts on either side of said U-shaped channel are isolated.
7. A method for forming a plurality of electrical wiring ducts in a building floor slab, as set forth in claim 6, and further including the steps of selectively attaching a plurality of access boxes to an upper surface of said cover plate for providing access into said ducts, and pouring a surface layer of a hardenable material over said slab and said cover plate.
8. A method for forming a plurality of electrical wiring ducts in a building floor slab comprising the steps of: forming said floor slab from a hardenable material with at least one trench formed in an upper surface of said slab;
after such material at leasts partially hardens, placing a U-shaped channel in said trench to divide said trench into three ducts; placing a metal cover over said trench and said U-shaped channel whereby a first duct is defined by said cover plate and said U-shaped channel and two other ducts are defined on either side of said first duct by said cover plate, said U-shaped channel and said trench; and adjusting the height of said U-shaped channel in said trench to completely isolate said two other ducts from each other.
after such material at leasts partially hardens, placing a U-shaped channel in said trench to divide said trench into three ducts; placing a metal cover over said trench and said U-shaped channel whereby a first duct is defined by said cover plate and said U-shaped channel and two other ducts are defined on either side of said first duct by said cover plate, said U-shaped channel and said trench; and adjusting the height of said U-shaped channel in said trench to completely isolate said two other ducts from each other.
9. A method for forming a plurality of electrical wiring ducts in a building floor slab, as set forth in claim 8, wherein the height of said U-shaped channel is adjusted prior to placing said cover over said trench and said U-shaped channel.
10. A method for forming a plurality of electrical wiring ducts in a building floor slab, as set forth in claim 8, and further including the steps of selectively attaching a plurality of access boxes to an upper surface of said cover plate for providing access into said ducts, and pouring a surface layer of a hardenable material over said slab and said cover plate.
11. A method for forming a building floor structure with a plurality of wiring ducts therein comprising the steps of: forming at least two floor slabs from a hardenable material with one-half of a trench extending along an upper edge of each slab; positioning said slabs with said trench halves abutting; grouting a joint extending between said floor slabs below said trench halves; and positioning a U-shaped channel along said grouted joint to divide said trench halves into at least two separate ducts and positioning a cover plate over said trench halves and said U-shaped channel.
12. A method for forming a building floor structure, as set forth in claim 11, and further including the steps of selectively attaching a plurality of access boxes to an upper surface of said cover plate for providing access into said ducts; and pouring a surface layer of a hardenable material over said slabs and said cover plate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA276,882A CA1070510A (en) | 1977-04-25 | 1977-04-25 | Method for forming wiring channels in a concrete floor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA276,882A CA1070510A (en) | 1977-04-25 | 1977-04-25 | Method for forming wiring channels in a concrete floor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070510A true CA1070510A (en) | 1980-01-29 |
Family
ID=4108489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA276,882A Expired CA1070510A (en) | 1977-04-25 | 1977-04-25 | Method for forming wiring channels in a concrete floor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1070510A (en) |
-
1977
- 1977-04-25 CA CA276,882A patent/CA1070510A/en not_active Expired
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