US1758989A - Underfloor duct system and method of making - Google Patents

Description

May 20, 1930. H. s. WALKER M 1,758,989

UNDERFLOOR DUCT SYSTEM ND METHOD OF MAKING Filed June 21, 1925 @9 Z f j@ ZZ m Z G f4 E BY M7 Q O ATTORNEYS Patented May 20, 1930 HERVEY S. WALKER, F lA RDZMORE, PENNSYLVANIA UNDERELooR DUCT `sYsTEM AND METHOD' or MAKING Application filed June 21,

Thisinvention relates to systems of electrical Wiring and is concerned more particularly with conduit or duct systems for instal. lation in buildings during the course of construction thereof. The presentsystem Ais ofv the concealed type with the ducts through which the conductors lare led placed eitherin thev fioors or in the Walls or partitions of the building, and the invention includes both a 1i. method of producing a novel duct system and also certain features of the system itself.

In modern buildings, especially oflice buildings, it has now become necessary to provide several different kinds of electrical lo service on each floor of the building, as high tension energy is required for lighting and small power devices, such as fans, and in addition telephone Wires and wiring for low tension signal systems, such as buzzers, an-

2) nunciators, and the like, are also required.

The conductors for these different services are concealed in accordance with present practice, and the conductors are led to the different parts of the floor in ducts which are built into the floor during the course of construction of the latter. lSuch systems are commonly referred to as underfloor Wiring systems.

In steel frame structures, such as modern office buildings, the floors consist of a rough fioor slab cast or built on suitable forms, this slab' having a rough upper surface which is finished in several different Ways. When a Wood fioo'r is to be employed, sleepers are laid on the rough slab and the iinished Wood flooring is then laid on the sleepers. Another type of floor includes a finishinglayer of cement mortar which is laid over a fill of'V cinder concrete lying on the fioor slab, and over this finishing layer, linoleum or some other similar finishing material is customarily employed. i

In the installation of a concealed wiring system in a floor of the type above generally described,'the ducts are placed in position during the construction of the floor and ordinarily laid in place on the rough floor slab, being then covered bythe cinder fill and by thenishing layer.v According to the pracy tice that has been used heretofore, the outlets from the ducts are placed in positioniin the ducts at places Wherever it is known in L,advance that outlets will be needed, prior tional to those originally installed are usually required. This is done by cutting through the fioor, exposing the duct, placing an outlet in position, and then patching the fioor around the outlet. This is an undesirable operation, involving much expense and inconvenience, particularly when carried on, as it usually is, when the floor space is in use.

The object of the present invention is to provide a system which overcomes these diiiculties, and is readily flexible in -use to meet varying requirements arising from. changes in points of energy demand on I,the floor. The system is further arranged so that changing the position and number of outlet connections is a simple matter requiring no considerable mutilation of the floor covering or surface. T o attain these objects, the system includes ducts provided with a large number of outlet fittings, or inserts at definite intervals along the ducts, these fittings being placed in position prior to the completion of the floor, and supplied at a spacing such that there is a greater number of fittings than would be required by the normal demand. These inserts extend upwardly from the duct which-lies beneath the fioor a substantial distance, to the level of the finished floor surface or slightly beneath it, and the outlet ends of the inserts which are not to be used for the passage of conductors are closed with caps which lie flush with the finishing layer of the floor and are normallv concealed by the linoleum. The ducts conimunicate with boxes which form centers of distribution, and the boxes are provided with covers which are exposed in the floor. As the inserts in the ducts are at a uniform spacing, the location of any insert may be readily ascertained by measurement from the box along' the ducts, and accordingly, although the inserts not in use are normally concealed, it is a simplematter to ascertain the posi- .of this type, long pads or bands of concrete at which current is desired, and a hole may then be cut in the linoleum, the insert opened i by removal of the cap, and connections to the conductors in the duct made in the usual lhile one form of the present wiring system frequently used includes ducts or con duits in the form of metal tubes in which the fittings or inserts are mounted, I also contemplate that the ducts may be provlded by molding channels in the floor during its construction, and in the installation of a system will be placed on the rough ioor slab and then channels formed in these pads in any convenient manner, as, forexample, by placing a sleeper in the top of the band before the concrete has set. The open trench so formed may then be closed in any convenient manner, as, for` example, by means of a metal plate which is provided at uniform intervals with apertures in which'are placed the tubular inserts providing the duct outlets. Such metal plates form the top wall of the duct, and the floor is then finished in the usual way, the metal plates being embedded in the ioor with the outlets extending through the latter to its upper surface. Preferably, the metal plate is strengthened by making it corrugated, although a suitable construction may also be provided by using a flat plate and then forming narrow seams in the n.` ishing layer of the ioor at either edge bf the metal. With this latter construction, the seams in the finishing layer permit the upper surface of the floor to yield slightly in` the event that heavy loads are moved .across the duct, so that the cracking of the lfloor is prevented.

In another form of duct suitable for the purpose, a similar pad or band of concrete is made, but the top of the channel formed in the band is closed by an arched plate. This construction ,permits the use of a relatively shallow channel, the space in the duct being afforded in part by the dorning of the cover plate.

In any of the ducts above described, the outlets are placed at uniform spacing in accordance with the principles laid down in my co-pending application, Ser. No. 63,355, filed Oct. 19. 1925. and which has matured into Patent #1,592,548 of which application the present one is a continuation in part.

For a better understanding of the present invention, reference may be had to the accompanying drawings, in which- Fig. 1 is a transverse vertical sectional view through one form of duct embodying the present invention,

Fig. 2 is a view similar to Fig. 1, showing a different type of duct,

ig. 3 is a view showing the manner in whic the duct shown in 1 is formed,

Fig. 4. is a view similar to Fig. 1, showing a different type-of coverplate,

Fig. 5 is a plan view of the cover plate used in the duct of Fig. 1,

Fig. 6 is a sectional view similar to Fig. 1, shfwmg a slightly modified type of that duct, an

Fig. 7 is a diagrammatic lay-out' showing a system including the duct shown in Fig. 1.

Referring now to the drawings, the system is'shown4 in Fig. 1 installed in a iioor which consists of a rough floor slab 10, made of concrete in the usual way. On the surface of thisslab is placed a la er of cinder iill 11, over which is placed the ishing floor layer 12 of cement mortar. As shown in Fig. 7 the system includes ducts 13 and 14 lying in the fioor. and extending at right angles to each other, these ducts leading to boxes 15 throughrwhich the conductors in the ducts are led. The boxes have covers 16 which lie flush with the finished floor surface, and upon removal of the covers access to the interior of the boxes is afforded. The arrangement of the ducts within the floor will vary with the particular installation,.but in anordinary building, ducts will be placed to run lengthwise and crosswise of the iioor at relatively short intervals.

The ducts may consist of metal tubes of square or round cross-section, such as that illustrated at 17 in Fig. 2. These ducts are placed on the surface of the floor slab 10 and connected to the boxes 15 prior to the laying of the filling material. Each duct is provided with a plurality of inserts 18 which are placed in the upper wall of the duct at uniform, relatively close spacing. For example, these inserts may be placed on 30 centers, and the inserts not to be used are closed by caps 19. The duct is supported in any convenient way on the Hoor slab, preferably being raised above the slab a 'short distance so as to be encased on all sides by the cinder fill, and the height of the supports and the length of the inserts is such that the caps lie flush with the surface of the finishing layer 12 or else a slight distance below. Such inserts as are required in nor mal use are opened by the removal of the caps and standpipes of any preferred form are placed in the inserts, the conductors be ing drawn through the duct and led through the inserts in the ordinary way.

By providing each duct with a plurality of inserts at relatively close spacing prior to the installation of the system'in the floor, it is possible to secure outlets in such number that no matter what part of the floor requires service, there will always be an insert near at hand and the use of this insert may be had without cutting the fioor and tapping the duct, as has been necessary in the previous systems. While such close spacing of the inserts will result in the presence in the floor of a larger number of inserts than will ordinarily be required by normal demand, still the inserts are of cheap metal construction 'and the cost of the excessive quantity of inserts is not materially greater than the cost of the ordinary number of brass outlets which have been commonly used for this purpose up to the present. Also, as thecaps of the inserts lie flush with the finishing layer of the fioor, or slightly beneath it, they are normally covered by the linoleum so that their presence in the floor is not undesirable.

Instead of using a metal duct such as is illustrated in Fig. 2, it is possible to employ a molded duct, as shown in Fig. l. In the construction of this duct, a pair of forms 20 is placed on the door, these forms` being of L-shape, and of any convenient material. The height of the upright legs of the forms and the spacing between the forms will depend on the needs of the particular installation- Between the upright legs is placed a quantity of concrete 21, and while this mass is still plastic, one or more channels 22 may be molded in it, as, forexample, by means of a sleeper 23. When the concrete sets, the channel 22 forms the major part of the duct, and this open channel may then be closed lby a cover plate, as, for example, that shown at 2l in Fig.'1. This cover plate is made of a sheet of metal, such as steel, and may be strengthened by lengthwise corrugations. The plate is provided with inserts 18 at uniform spacing, as shown in Fig. 5, and the duct is thus defined in part by the walls molded in the concrete band, and in part by the metal plate. The height of the pad will depend on the thickness of the finishing layer of the fioor and the depth of the cinder fill, and the length of the inserts will be such that'when the plate is in position the tops of the inserts will lie flush with the upper surface of thefinishing layer, or slightly below it.

The strengthening of the metal plate by corrugations or in any other convenient many ner, is desirable in order to prevent the slight collapse of the upper wall of the duct that might result if a heavy load were moved across theduct` but this difficulty may also be obviated bv using the construction shown in Fig. 6. This includes a flat metal plate 25 forming the upper wall of the duct 22 and having inserts 18 atdefinite uniform and relatively close spacing. As is the case with v,the corrugated plate. the edges of the flat plate are provided with downwardly extending flanges 26 which overlie the edges of the pad or band of concrete 21. lVhen this flat plate 25 is used. the finishing fioor layer is slotted as at 27. this permitting that part of the finishing fioor layer 28 which overlies the duct to yield slightly as the plate yields when loads are moved across the duct. y

In some instances it may be "desirable to make a duct in which the channel 22 formed in the band of concrete is relatively shallow, additional space in the duct being secured by using a domed cover plate 29. This cover plate has an upward bulge over the channel.

22, but is otherwise similar to the plates 25 and 24. v

vith any of the ducts employed in the present system, the inserts communicating with the duct through 'its upper wall are embedded in the floor itself, and are disposed at a relatively short spacing.` The duct thus lies embedded a substantial distance beneath the finished floor surface, but outlets from. the duct are available in the floor surface short distances apart. The molded ducts i1- lustrated in Figs. l, 4, and 6 may be formed without difliculty during the construction of the floor, while the duct shown in Fig. 2 is prepared in advance and placed in the floor at the appropriate time. With the molded duct, the cover plate may be placed in position over the channel and the inserts then inserted in it prior to completion of the floor, orl the inserts may be placed in the plate before the latter is installed to cover the channel. The outlet fittings for use with the metal duct shown in Fig. 2, may likewise be placed in position in t-he duct wall at the time of its manufacture 4or, else just before its installation.

I claim v 1. In a method of constructing a concealed y the plate with the interior of the duct, and,

laying the upper layers of Hoor material on vthe said intermediate level to enclose and conceal the duct and the outlet fittings, the top surface of the fioor lying substantially at the level of the tops of the outlet fittings.

2. In a concealed wiring system for use in concrete buildings. a duct adapted to be disposed wholly within the floor structure at a substantial distance beneath the finished floor surface, which comprises the combination of a band of fioor material laidon an intermediate level of the floor and having an opentop channel formed in its upper surface, a metal plate covering the top of the channel and with it defining the duct, and a plurality of tubular inserts mounted `in the plate at selected intervals, these inserts havingoutlet endsv through which access to the interior of the duct may be had through the finished fioor surface.

3. In a concealed wiring system for use in concrete buildings, a duct adapted to be disposed wholly within the floor structure at a substantial distance beneath the finished floorN surface, which comprises a band of floor ma v terial lying on an intermediate level of the floor and having an open-top channel formed in its upper surface, a reinforcing plate lying on the top of theband and closing the channel, and a plurality of similar tubular inserts mounted in the plate lengthwise of the channel at predetermined, uniform, relatively short intervals, the plate and inserts being adapted to be enclosed and concealed by the upper layers of the ioor with the inserts extending to the upper level of the finishing floor layer and affording access to the interior of the duct through their outlet openings.

4. In a method of constructing a concealed wiring system in the floor of a building, the steps of laying a band of floor ma-y terial upon an intermediate level of the floor, forming a channel in the upper face of this band. closing the channel to complete the duct by a plate carrying a plurality of outlet fittings of similar height, and laying up` per layers of floor material over the said intermediate level to enclose and conceal the duct and the said outlet fittings, the top surface of the floor being laid to lie substantially flush with the level of the tops of said fittings.

5. In a method of constructin a concealed Wiring systemv in the floor of a uilding, the steps of laying a band of floor material upon an intermediate level of the floor, forming a channel in the upper surface of this band mounting a plurality of outlet fittings of similar height in a row and at selected intervals in a plate, closing the channel to complete the duct by placing the plate on the band, and laying upper layers of floor material over the said intermediate level to enclose and conceal the duct and said fittings and to form a finished floor surface substantially fiush with the level of the tops of said fittings. e

6. The method of constructing a door having a concealed wiring system therein, which comprises .forming a slab of floor material, placing a band of floor material on top of this slab, this bandhaving an open channel in its upper surface, closing the channel by means of a plate having a plurality of outlet fittings of similar height mounted therein, and placing a layer offilling material on theV slab and a finishing layer over the filling material, the said layers being placed so that the upper surface of the finishing ylayer lies substantially flush with the level of the tops `of the said fittings.

7. The method of constructin a floor having a concealed wiring system t erein, which comprises placing outlet boxes on an'intermediate level of the cor, forming bands of floor material on the said intermediate level between the boxes, vthis band having an open channel in its upper surface ommunicatmg with the-interior of the boxes, closing the the tops of the boxes and fittings lying su l stantially at the level of the upper surface of the said finished floor.

8. The method` of constructing a floor hav- I ing a concealed Wiring system therein, which comprises formingaslab of fioor material, mounting outlet boxeslfon this slab, forming a band of fioor materia'ontop of thelslab between adjacent outlet boxes, this band being provided with an open channel in its upper surface, closing the channel by means of a plate having a plurality of outlet fittings of similar height mounted therein, and placing a layer of filling materialen the slab and a finishing layer over the filling material, the upper surface of the finishing layer lying substantially flush with the level of the tops of the said fittings and the tops of the said outlet boxes.

9. The method of constructing a fioor having a concealed Wiring system therein, which comprises forming a slab of floor material, molding a band of floor material on the top of this slab, this band being formed with an open channel in its upper surface, closing the channel by means of a plate having a plurality of outlet fittings of similar height mounted therein, and laying upper layers of floor material on the saidintermediate level to enclose and conceal the duct formed by the band and the plate and also to partially conceal the said outlet fittings, the top surface of the -fioor being laid to lie substantially flush with the level of the tops of the said fittings.

10. A ioor construction having a concealed wiring duct therein, which comprises a fioor slab, a band of floor material lying on the slab and having an open-top channel formed in its upper surface, a plate lying on top of the band and closing the channel to form a top of the finishing layer of the floor lying substantially flush with the tops of the fittings. 1

11. In a floor construction, the combination of a band of Hoor material laid on an intermediate level of the floor, this band 'having an open channel in its upper surface, a metal plate having a; plurality of outl let fittings of similar height mounted therein placed on the band to close `the channel and complete av wiring duct, upper layers of floor material laid on said intermediate level to-, complete the floor and to enclose the duct and the outlet Iittings,and narrow open channels formed in the upper surface of the Hoor lying parallel and lengthwise of the duct adjacent either' edge of the plate. Y

12. In a floor construction, the combination of a slab of floor material, a band of e, ioor material laid on the slab and having an open channel in its upper surface, a plate closing the channel and having a vplurality of outlet fittings of similar height mounted lo therein, a layer of filling material on the slab extending substantially to the top of the band, and a finishing layer over the filling material concealing the plate, the outlet fittings projecting through the finishing layer and lying with their tops substantially level with the upper surface thereof.

13. In a Hoor construction, the combina tion of a wiring duct Within the floor structure below the floor surface, this duct being defined in part by a portion of the floor material having a channel therein and in part by a metal plate forming the top wall thereof, and a plurality of outlet fittings of tubular form extending upwardly from the duct toward the floor surface and held in place at least in part by the finishing layer of the ioor in which said fittings are embedded. f

In testimony whereof I aiiix my signature.

HERVEY S. WALKER. C

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