GB2052182A - Insulator for flat cable installation - Google Patents

Abstract

An insulator for covering an electric cable has a spacer 166 with circular recesses 168 for receiving portions of an electrical connector 132 which extend beyond a surface of tho cable 110 covered by the insulator. Two cables 110, 120 are joined by connector 132 and another insulator may be provided below the lower cable 120. The diameter of each recess is chosen so as to closely accommodate the connector and to provide a substantial barrier to prevent moisture, dirt and other contaminants from reaching the connector. The insulator has a transparent cover 170 on one side and an adhesive layer (172, Fig. 2 not shown) on the other. The recesses are spaced (Fig. 1 not shown) to accommodate the selected connections (132 to 138 Fig. 3 not shown) between the flat cables. <IMAGE>

Description

SPECIFICATION Insulator for covering electrical cables The present invention relates to insulators for covering electric cables and, more particularly, to such insulators which are especially adapted for use in connection with flat multiconductor cables.

In the copending UK Patent Application 8017084 (ref. T Er B 824 F) which claims priority from U.S. Patent Applications, Serial Nos.

06/042,709 and 06/042,544 both filed on the 25th May 1979, there is disclosed a technique for connecting flat multiconductor cables. Briefly described, the method disclosed in that Application involves overlapping a pair of flat multiconductor cables and then mechanically and electrically connecting the overlapping portions of the cables using metallic connectors with extend beyond the surface of at least one of the cables.

Any connector which electrically connects two "hot", i.e. electrically energized, conductors also becomes electrically energized and therefore potentially dangerous, inasmuch as an individual who touches the connector, either directly or indirectly, could receive a serious electric shock.

In order to electrically insulate the connectors, it has been proposed to cover them with a flat sheet of relatively flexible electric insulation.

Because the cable is designed preferably for undercarpet installation, it is undesirable to use a thick sheet of insulation which might, due to its thickness, create bulges in the carpet. Should the thickness of such insulation be decreased in an effort to prevent the formation of unsightly bulges in the overlying carpet, the insulation becomes more susceptible to puncture or piercing by the relatively sharp edges of the connectors when the carpet above is walked on. Pierced or punctured insulation results in the same potentially hazardous condition that exists when the connectors are not covered by any insulation whatsoever. Moreover, the piercing or puncturing of the insulation increases the possibility of eventual electrical "tracking" or arcing between the partially exposed connectors.

In addition, the flat multiconductor cable as described in the above mentioned copending UK Patent Application, has a series of parallel flat, insulated conductors separated from adjacent conductors by flattened depressed regions of insulation which, when scored, lend themselves to tearing should it be desired to separate the conductors from one another. These flattened, depressed regions are significantly thinner than the adjacent conductor insulation portions of the cable. As a result, insulating spacers placed on such cable insulation would fail to conform to the depressed regions leaving pathways between the cable surface and the insulating spacers where moisture, dirt or other contaminants can enter.

Thus, improper sealing of the connectors from these depressed regions can cause the connectors to be subjected to moisture, dirt or contaminants contained therein, ieading to a shorting of or other injury to the joints and cables.

It is an object of the present invention to provide an improved insulator for multiconductor cables.

It is another object of the this invention to provide an improved insulator that seals the connectors of joined flat multiconductor cables from the surrounding environment.

In accordance with the invention, there is provided an insulator with a spacer which supports electric insulation a distance from an adjacent surface of an electric cable and accommodates protruding portions of any connectors which extend beyond the surface of the cable. The distance between the insulation and the surface of the cable may be selected so as to inhibit the connectors from cutting into the insulation, thereby preserving the integrity of the insulation to avoid the safety and electrical tracking problems described hereinabove.

In one particular embodiment, the spacer is adapted to insulate joined cables that have a central portion of predetermined thickness and at the marginal edges thereof, flat depressed regions of thickness less than the central portions. Electric conductors extend within the central portions and the connectors joining such cables extend beyond the exterior surface of the central portion. The spacer is made from a relatively noncompressible, nonconductive material having a plurality of openings therein. The spacer is located on the central portions of the cable with the openings being arranged to completely surround the connectors. Thus, barriers between the flat depressed regions and the connectors are formed, sealing the connectors from any moisture, dirt or contaminants that may be contained in the depressed regions.

FIG. 1 is a plan view of an insulator for covering electric cables constructed in accordance with the concepts of the invention.

FIG. 2 is a side elevational view, in section, of the insulator of FIG. 1 taken along the lines of 2-2 in FIG. 1.

FIG. 3 is a plan view of two overlapping flat multiconductor cables coupled to one another by a series of connectors.

FIG. 4 is a side elevation, in section, of one of the flat multiconductor cables of FIG. 3 taken along the lines 4 4.

FIG. 5 is a side elevation, in section, of a flat multiconductor cable with an insulator adhered thereto useful in describing a preferred embodiment of the invention.

FIG. 6 is a side elevation, in section, of a flat multiconductor cable with an insulator constructed in accordance with the invention adhered thereto.

FIG. 7 is a side elevation, in section, of a joint between two flat multiconductor cables insulated on both sides with insulators in accordance with the invention.

Turning now to FIGS. 3 and 4, a first flat multiconductor cable 110 has its individual conductors 112, 114, 16 and 118 joined to like individual conductors 122, 124, 126 and 128, respectively, of a second flat multiconductor cable 120 by connectors 132, 134, 136 and 138, respectively. Connectors 132, 134, 136 and 138 may be any suitable connectors such as are disclosed, for example, in the copending UK Patent Application (ref. T Er B 829F) 8017082 claiming priority from U.S. Patent Application, Serial No. 042,441 by T.L.C.Kuo, filed on May 25, 1 979 and entitled "Self-Locking Clamp Member." As is best seen in FIG. 4, the conductors are generally rectangular and are covered on both long sides by layers of insulation 130 and 140.

The layers of insulation 130 and 140 are adhered to themselves in the interstices between adjacent conductors as at 142, 144, 1-46 and at the cables ends at 148 and 1 50. In that there is no conductor at such locations, a flattened, depressed region is created having a width significantly less than the adjacent areas where a conductor is located resulting in a natural trough or passage along the longitudinal axis of the cable 110. Similar depressed regions are found in cable 120 as at 1 52, 154 and 1 56 and at the cable ends 1 58 and 160. A score line, such as 1 62 in depressed region 142, may extend down the center at each of the depressed regions to permit the individual conductors to be separated from the full cable.

Thus, conductor 112 can be removed from cable 110 by tearing along score line 162 in the depressed region 142.

As stated above, the presence of a bare metallic connector such as 132, 134, 136 or 138 engaging an energized conductor such as 112, 114,116,118,122,124,126 or 128 itself becomes electrically "hot" so that one contacting such a connector could receive a severe electrical shock. To prevent this from happening, an insulator constructed in accordance with the present invention is provided. As shown in Figures 1 and 2, an insulator 1 64 comprises a spacer 166, preferably made fro-m a noncompressible, electrically insulating material, such as polyvinylchloride. Spacer 1 66 is sized and shaped so as to completely cover and preferably overhang overlapping portions of the flat multi conductor cables 110 and 120 respectively (see Figure 3).

Although the spacer 1 66 is illustrated as being square in Figure 1, it may have any other suitable shape depending upon the configuration of the overlapping portions of the cables 110 and 120, respectively.

A plurality of holes 1 68 extend through the spacer 166, the holes 1 68 being sized to receive therein the arms of the connectors 132, 134, 136 and 1 38 joining the overlapping cables 110 and 120, respectively. As will be described, the holes 1 68 are suitably formed to inhibit tracking between the connectors as well as to seal these connectors from the environment. Preferably, for manufacturing purposes, the holes 1 68 are circular, although they may have other geometric shapes.

Included on the spacer 166, is a thin film of electric insulation 170, preferably clear for alignment purposes and laminated to one of the faces of the spacer 1 66. On the opposite surface of the spacer 1-66 is a layer of pressure-sensitive adhesive 1 72 that is protected until use by a layer of removable release material 1 74. The insulator 1 64 preferably includes a circular aperture 1 76 and an elongated slot 1 78 through the spacer 1 66 to enable the insulator 1 64 to be positioned upon a suitable tool for aligning the insulator 1 64 with the cables it is to insulate.

The liner 1 74 prevents the inadvertent sticking of the pressure-sensitive adhesive 1 72 to the cables 110 and 120 or other objects. Preferably, the liner 22 is made from clear plastic so that the aperture 176 and slot 178 may be easily observed therethrough.

The film 170 of electric insulation can be made from any suitable material, such as a laminate of polyvinyl-chloride and polyester adapted for lamination to the spacer 1 66. Alternately, the film 1 70 may be formed monolithically with the spacer 166.

In order to prevent the film 1 70 from being pierced or punctured by the arms (see Fig. 3) of the connectors 132, 134, 136 and 138, the film 1 70 is supported a predetermined, substantially fixed distance from the arms of these connectors by the spacer 1 66. The thickness of the spacer 1 66 may be varied to vary the distance between the connector arms and the film 14, as long as the spacer 166 is thicker than the distance the connector arms project above the exterior surface of the joined cables 110 and 120, respectively.

In the preferred embodiment, the spacer 1 66 is formed to seal the connectors from each other and from any contaminants that may be contained within the depressed regions of the cables. To effect such a seal, the holes 168, as shown in Figure 6, are formed large enough to closely accept and fully surround the connectors and are spaced from each to lie in substantial registry with the thicker, central portions of the cable 110 within which the conductors 112, 114, 11 6 and 11 8 extend.The diameters of the holes 1 68, centered over the respective conductors, are formed to be less than the lateral distance between the depressed regions that extend along the marginal edges of each of the central portions containing the conductors, so that the holes 1 68 do not extend over any of the depressed regions, 142, 144 and 146. Thus, the portions of the spacer 1 66 on the central cable portions extending from the walls of the holes 1 68 establish an insulative barrier between the connectors 132, 134, 136 and 138 and the flat, depressed regions 142, 144 and 146.

The significance of the preferred sealing structure can be more fully understood by reference to Figure 5. In this arrangement, an insulator 10 comprising an insulative spacer 12 with an insulation layer 14 and an adhesive film 18 thereon, includes a plurality of apertures 32.

The apertures 32 are formed to receive connectors therein, the diameters being larger than the lateral distance between depressed regions, whereby portions of the holes 32 overlie the recessed regions 142, 144 and 146. In such a structure an undesirable passageway is created from the depressed regions 142, 144 and 146 to the connectors that extend into the holes 32, resulting potentially in short circuits or electrical arcing.

While the insulator 164 of the present invention is preferably configured to seal the connectors joining multiconductor cables with recessed portions, it should be understood that the present insulator is not limited thereto. The present insulator may also be readily used with multiconductor cable wherein the exterior surfaces are substantially flat thereacross. With such flat cable, the insulator configuration shown in Figure 5 would not present the potential tracking problems as the depressed portions 142, 144 and 146 would not be present. Furthermore, with flat cable, the connectors may be only partially surrounded and barriers between connectors would not be necessary where no troughs or depressions are present to carry or otherwise contain contaminants.Moreover, the spacing between the insulation 1 70 and the arms of the connectors 132, 134, 136 and 138 may also be effected by separate spacer elements positioned on the cables at a distance to sufficiently receive the connectors therebetween.

Referring back to Figure 3, a typical splice is shown in which the cables 110 and 120 are perpendicular to each other. The four conductors 112,114, 116and 1 18 of the cable 110are electrically and mechanically connected to the corresponding four conductors 122, 124, 1 26 and 128 of the cable 120 by the connectors 132, 134, 1 36 and 138, respectively. The four connectors extend diagonally across the overlapping portions of the spliced cables 110 and 120.

When applying the insulator 1 64 to the overlapping cable 110, the liner 1 74 is removed in a suitable manner to expose the pressure-sensitive adhesive 1 72. Upon proper installation of the insulator 1 64. the arms of the connectors 132, 134, 136 and 138 will register with four of the holes 168 which are aligned diagonally across the face of the spacer 1 66 (see Figure 1). The other diagonal hole may be used when insulating a tap splice between five-conductor cables. The two longitudinally aligned holes together with the middle one of the five diagonal holes may be used to selectively connect one conductor of a cable to three corresponding cables of an overlapping cable.Of course, the number and arrangement of the holes may be varied depending upon the configuration of the connectors.

In Figure 7, there is shown a completed splice of flat multiconductor cables 110 and 120 with spacers 166 positioned above and below a joint formed, for example, by the connector 132. It is preferable to form the insulators for such applications such that the spacers 1 66 overhang the overlapping region of the joined cables 110 and 1 20. The overhanging spacer portions (not shown) may be adhered to each other by means of the pressure-sensitive adhesive on each spacer so as to completely envelop the joining connectors and joined overlapping portions of the cables 110 and 120. To further assure a seal from the environment, the interior surfaces of the overlapping portions of the cables 110 and 120 may be coated with a filler material such as a mastic.

It should be appreciated that the embodiments described herein are merely exemplary and that a person skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. For instance, the insulator of the present invention may be applied to round electric cable as well as to flat multiconductor cable. Also, the insulator is equally suitable for use in convering any overlapped portions of a pair of cables which are spliced together by, for example, a butt splice or any other type of splice. All such modifications and variations are intended to be inciuded within the scope of the invention as defined in the appended

Claims (11)

claims. CLAIMS

1. An insulator for insulating the juncture between two or more electric cables each having one or more conductors wherein a connector joining selective conductors extends beyond the exterior surface of the surreunding joined electric cables a first predetermined height, comprising: a plurality of spacer means each having second predetermined heights above the surrounding joined electric cables, said second predetermined heights being greater than said first predetermined height, said spacer means at-least partially surrounding said connector and spaced apart sufficiently to receive such connector therebetween; and insulation means engaging a first surface of said spacer means and supported over said connector when said spacer means are positioned adjacent a connector.

2. An insulator according to claim 1, wherein said plurality of spacer means fully surrounds said joining connector.

3. An insulator according to claim 2, wherein each of said cables has a central portion of predetermined thickness and at the marginal edges thereof, flat depressed regions of thickness less than the thickness of the central portion, the conductors extending within said central portion, the joining connector extending beyond the exterior surface of said central portion, and wherein the spacer means surrounding said connector is located on said central portion to form a barrier between said flat depressed regions and such connector.

4. An insulator according to claim 3, wherein said surrounding spacer means define an aperture in register with said central portion, the walls of said aperture being spaced apart in the direction transverse to said depressed regions less than the lateral distance therebetween.

5. An insulator according to claim 4, wherein said cables are multiconductor cables and a predetermined pattern of individual joints between prescribed conductors of such conductors are made, wherein said spacer means is an electrically non-conductive spacer member having a plurality of apertures equal in number to and positioned according to the individual joining connectors.

6. An insulator according to claim 5, wherein said apertures are circular for receiving said joining connectors.

7. An insulator according to claim 4, further including means for locating said insulator with respect to said joints, said locating means including an opening extending through said member to permit positioning said apertures over said connectors.

8. An insulator according to claim 4, wherein a plurality of apertures lie along a diagonal line so as to overlie the joints of the conductors of a first cable individually with an associated conductor of a second cable placed substantially orthogonally to said first cable.

9. An insulator according to claim 4, wherein an adhesive layer is placed on the second surface of said spacer member to adhere said spacer member to the central portions of said cables adjacent a connector.

10. An insulator according to claim 9, wherein the surface of said adhesive layer not engaging the second surface of the spacer member is engaged by a liner means removably attached to said adhesive layer for preventing the inadvertent adhesion of said adhesive layer to another object until said liner means is removed from said adhesive layer.

11. An insulator substantially as herein described with reference to Figs. 1 and 2 of the accompanying drawings.