Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention relates to insulators fbr
covering electric cables and, more particulqr~y! to such
insulators which are especially adapted for use in connec~
tion with flat multiconductor cables.
BACKGROUND OF THE INVENTION
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In copending Canadian Patent Application Serial
No. 352,576, filed on May 23, 1980, which is owned by the
assignee of the present invention, there is disclosed a
technique for connecting flat multiconductor cables. Brief-
ly described, the method disciosed in that application in-
volves overlapping a pair of flat multiconductor cables and
then mechanically and electrically connecting the overlapping
portions of the cables using metallic connectors which extend
beyond the surface of at least one of the cables. Any connector
which electrically connects two "hot", i.e. electrically ener-
gized, 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 or rela-
tively flexible electric insulation. Because the cable is I
designed preferably for undercarpet installation, it is unde-
sirable 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
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when the carpet above is walked on. Pierced or punctured
insulation results in the same potential.ly hazardous con-
dition that exists when the connectors are not covered by
any insùlation whatsoever. Moreover~ the piercing or
puncturing of the insulation increases the possibility of
eventual electrical "tracking" or arcing between the parti-
ally exposed connectors.
In addition, the flat multiconductor cable, as
described in the aforementioned application, has a series
of parallel flat, insulated conductors separated from adja-
cent conductors by flattened depressed regions of insulation
which, when scored, lend themselves to tearing should it be
desired to separate the conductors ~rom 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 insula-
tion 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 conn.ectors to be subjected to moisture,
dirt or contaminants contained therein~ leading to a shorting
of or other injury to the joints and cables.
SUMMARY~ OF T~IE INVENTION
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Broadly speaking the present invention oyercomes
the problems of the prior art by providing an insulator for
insulating the juncture between two or more electric cables
each having one or more conductors wherein a connector joining
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selective conductors extends be~ond the exterior surface
of the surrounding joined electric cables a first predeter-
mined height, comprising: a plurality of spacer means each
having second predetermined heights above the surrounding
joined electric cables, the second predetermined heiyhts
being yreater than the first predetermined height, the
spacer means at least partially surrounding the connector
and spaced apart sufficiently to receive such connector
therebetween; and insulation means engaging a first surface
of the spacer means and supported over the connector when
the spacer means are positioned adjacent a connector.
In one particula~ embod~i,ment, the spacer is adapted
to insulate joined cables th~at have a cëntr,al port1on of pre-
determined thickness and at the marginal edges thereof, flat
depressed regions of thickness less than the central portions.
Electric conductors extend wlthin th,e 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, seal-
ing the connectors from any moisture~ dirt or contaminants
that may be contained in the depressed regions.
BRIEF DESCRIPTION O,F THE DRAWING
FIG. 1 is a plan view of an insulator for covering
electric cables constructed in accordance wi,th the concepts
of the invention.,
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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 use-
ful in describing a preferred embodiment of the invention.
FIG. 6 is a side elevation, in section, of a
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flat multiconductor cable with an insulator cons-tructed
in accordance with the invention adhered thereto.
FIG. 7 is a slde elevation, in section, of a
joint between two flat multiconductor cables insulated on
both sides with insulators in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
,
Turning now to FIGS. 3 and 4, a first flat multi-
conductor cable 110 has its individual conductors 112, 114,
116 and 118 joined to like individua3 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 connect-
ors such as are disclosed, for example, in copending Canadian
Patent Application Serial No. 352,563 filed on May 23, 1980
and assigned to the assignee of the present invention. As
is best seen in FIG. 4, the conductors are generally rec
tangular 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, 146 and at the cables
ends as at 148 and 150. In that there is no conductor at
such locations, a flattened, depressed re~ion 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 152,
154 and 156 and at the cable ends 158 and 160. A score
line, such as 162 in depressed region 142, may extend down
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the center of each of the depressed regions to pe~mit
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 energiz-
ed conductor such as 112, 114, 116, 118, 122, 124, 126 or
128 itself becomes electrically "hot" so that one contact-
ing such a connector could receive a severe electrical
shock. To prevent this from happening, an insulator con-
structed in accordance with the present invention is pro-
vided. As shown in Figures 1 and 2, an insulator 164 com--
prises a spacer 166, preferably made from a noncompressible,
electrically insulating material, such as polyvinylchloride.
Spacer 166 is sized and shaped so as to completely cover
and preferably overhang overlapping portions of the flat
multiconductor cables 110 and 120 respectively (see Figure
3). Although the spacer 166 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 168 extend through the spacer 166,
the holes 168 being sized to receive therein the arms of the
connectors 132, 134, 136 and 138 joining the overlapping
cables 110 and 120, respectively. As will be described, the
holes 168 are suitably formed to inhibit tracking between
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the connectors as well æ to seal these connectors fro~ the environ-
ment. Preferclbly, for manufacturing purposes, the holes 168 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 ]aminated
to one of the faces of the spacer 166. On the opposite surface of
the spacer 166 is a layer of pressure-sensitive adhesive 172 that is
protected until use by a layer of removable release material 174. The
insulator 164 preferably includes a circular apertuxe 176 and an
elongated slot 178 through the spacer 166 to enable the insulator
164 to be positioned upon a suit~ble tool for aligning the insulator
164 with the cables it is to insulate.
The liner 174 prevents the inadvertent sticking of the
pressure-sensitive adhesive 172 to the cables 110 and 120 or other
c~ects. 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
suitabIe material, such as a laminate of polyvinylchloride and polyester
adapted for lamination to the spacer 166. Alternately, the filn 170
may be formed monolithically with the spacer 166.
In order to prevent the fi~m 170 fron being pierced or pun-
ctured by the arms (see Fig. 3) of the connectors 132, 134, 136 and 138,
the film 170 is supported a predetermined, substantially fixed distance
from the arms of these connectors by the spacer 166. The thickness of
the spacer 166 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.
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In the preferred embodiment~ the spacer ~66 is
formed to seal the connec-tors 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 o the cable 110 within which
the conductors 112, 114, 116 and 118 extend. The diameters
of the holes 168, 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
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1 the conductors, so that thc holes 168 do not extend over
any of the depressed regions, 142, 144 and 146. Thus,
the E~ortions of the spac~r 166 on the central cable
portions extending from the walls of the holes 168
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
30 portions 142, 144 and 146 would not be present~ Further-
more, 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 170 and the arms of the
connectors 132, 134, 136 and 138 may also be effected by
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1 separate sE~accr elements positione~ on the cables at a
distance to sufficiently receive the connectors there-
between.
Referring back to Figure 3, a typical splice is
shown in which the cables 110 and 120 are perpendicular
to each other. The four conduetors 112, 114, 116 and 118
of the cable 110 are electrically and mechanically
connected to the corresponding four conductors 122, 124,
126 and 128 of the cable 120 by the connectors 132, 134,
10 136 and 138, respectively. The four connectors extend
diagonally across the overlapping portions of the spliced
cables 110 and 120.
When applying the insulator 164 to the o~erlapping
cable 110, the liner 174 is removed in a suitable manner
to expose the pressure-sensitive adhesive 172. Upon
proper installation of the insulator 164, 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 166 (see Figure 1). The other diagonal
hole may be used when insulating a tap spliee between
five-conductor eables. The two longitudinally aligned
holes together with the middle one of the five diagonal
holes may be used to selectively eonneet one eonduetor of
a cable to three corresponding eables of an overlapping
cable. Of eourse, the numher and arrangement of the
holes may be varied depending upon the configuration of
the connectors.
In Figure 7, there is shown a eompleted spliee of
flat multiconduetor eables 110 and 120 with spaeers 166
positioned above and below a joint formed, for example,
by the eonneetor 132. It is preferable to form the
insulators for such applications sueh that the spaeers
166 overhang the overlapping region of the joined eables
110 and 120. The overhanging spaeer portions (not shown)
may be adhered to eaeh other by means of the pressure-
sensitive adhesive on each spaeer so as to eompletely
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1 ellvelo~- thc joining connectors and joined overlapping
portions oE 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
included within the scope of the invention as defined in
the appended claims.
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