US 3523156 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Aug. 4, 1970 PHILLIPS, JR
ELECTRICAL SERVICE CENTER HAVING AN IMPROVED MOISTURE BARRIER Filed Sept. 18, 1968 m, M m W W Z MV a 4 F 9 4 United States Patent O Int. Cl. H02g 3/08 US. Cl. 174-38 Claims ABSTRACT OF THE DISCLOSURE The moisture barrier is fabricated from a readily deformable, rubber-like material and is mounted in the service centers housing between its base and upper portion to prevent ground moisture from entering the upper portion and affecting moisture sensitive electrical elements. The moisture barrier has a plurality of conductor passages which have a generally hourglass-like shape. An hourglass-shaped plug is provided for each of the conductor passages. Small conductors pass through the moisture barrier with the plugs in place. Larger conductors pass through the moisture barrier with the plugs removed. The moisture barrier is compressed to provide a moisture seal against the conductors when a cover plate mounting a compressive member of the moisture barrier is installed on the housing.
BACKGROUND OF THE INVENTION The present invention relates in general to electrical service centers having moisture barriers to prevent ground moisture from affecting moisture sensitive electrical elements such as exposed conductors, bus bars and circuit breakers. In particular, the present invention relates to electrical service centers having an improved moisture barrier fabricated from a readily deformable rubber-like material.
Electrical service centers are widely used in such locations as mobile trailer parks for providing service and circuit protection for mobile homes. A typical service center includes a housing or pedestal having a base installed in the ground and an upper portion above the ground containing such moisture sensitive electrical circuit elements as circuits breakers, bus bars, conductors and the like. Ground moisture must be prevented from entering the portion of the housing or pedestal containing the moisture sensitive elements.
Previously, a barrier against moisture was provided by a steel plate below the upper portion of the housing or pedestal through which conductors or wiring passed. The holes or passages in the plate were sealed either by using grommets about individual conductors or sealing compounds hand-applied about the conductors. Without special tooling, grommets are diflicult to correctly install. The so-called add-on sealants, while effective, are often not applied correctly, necessitating a reapplication of the sealing material at a later time.
Moreover, grommets are sized to accommodate a given size conductor and plate opening. However, depending on the particular service center rating, different conductor sizes may be required. With a large number of possible conductor sizes, many different sizes of grommets are necessary. The same problem is evident with an add-on sealant, in that the passages through the barrier plate must be large enough to accommodate the largest expected conductor diameter. When a smaller conductor is used, the add-on sealant must bridge a relatively large space over the passage in the plate to the conductor.
Thus, there is a present need for a moisture barrier for use with electrical service centers which provides an effective block against moisture entering the upper portion of the service center, which is easy to use, and which is sufficiently flexible to accommodate different diameter conductors.
SUMMARY OF THE INVENTION The present invention provides an improved electrical service center which employs a moisture barrier fabricated from a readily deformable, rubber-like material through which conductors may pass and which effects a seal against the conductors by being compressed.
In one form, the present invention contemplates an electrical service center for supplying electrical energy of the type employing a housing or pedestal for enclosing circuit elements and conductors. An improved moisture barrier is disposed in the housing below the upper portion thereof. The moisture barrier has a plurality of conductor passages for the passage of conductors into the housings upper portion. Means associated with the housing, such as a cover plate, are provided for compressing the moisture barrier such that the walls of its conductor passages compress tightly in moisture sealing engagement against the conductors passing through them.
Preferably, the conductor passages of the moisture barrier are configured in a generally hourglass-like shape. Moisture blocking plugs, complementarily configured in an hourglass shape to be received in the conductor passages, are also provided. The plugs may be removed to accommodate a relatively large diameter conductor. When a small diameter conductor is to be used, the plugs are preferably in place. The hourglass configuration of the conductor passages provides a very effective moisture seal against conductors of various diameters. With larger diameter conductors, wall material about the throat of the hourglass-shaped conductor passage is displaced by the conductor. With smaller diameter conductors, of sufficiently large diameter so as to call for the removal of the complementary plug, the small diameter throat of the conductor passage is more proximate the conductor than the ends of the conductor passage and therefore augments the seal when the moisture barrier is compressed.
It is also preferred to provide as a part of the moisture barrier a compression member which is carried by a removable cover of the housing. This compression member is also fabricated from a readily deformable, rubberlike material such as sponge rubber or polyurethane foam.
The compression member is disposed to bear against the portion of the moisture barrier having the conductor passages, the conductor receiving portion of the moisture barrier, to compress such portion tightly against the conductors which it receives,
In addition, it is preferred to mount the moisture barriers compression member and conductor receiving portion in a pair of channel-like brackets attached to the removable cover and the housing. The opposed walls of these channel-like members act to reinforce the compression member and conductor receiving portion against lateral displacement which would tend to break the compressive engagement between the two. Additional rigidity may be provided by a stiffener carried in one of the channel-like mounting brackets on one side of the conductor receiving portion of the moisture barrier. This stiffener may have cutout portions which complement slits in the moisture barrier to aid in the ease of installing the conductors through the moisture barrier.
The moisture barrier and electrical service center of the present invention provide an effective block against ground moisture reaching exposed or moisture sensitive electrical elements contained in the upper portion of the service centers housing or pedestal. By forming the moisture barrier of a readily deformable, rubber-like material, the moisture barrier is deformed in compression to compressively engage conductors or wires passing through it. This compressive engagement provides a moisture seal or block. By providing the moisture barrier with hourglass-shaped conductor passages and plugs, unneeded passages are effectively blocked by the complementary, hourglass-shaped plugs against moisture passage. The hourglass configuration also effectively retains the plugs with the conductor receiving portion of the moisture barrier during shipment and storage. Moreover, the moisture barrier admits to simple and fast installation of conductors. In a preferred form, the conductors are merely pressed through the slits into the conductor passages.
These and other features, aspects and advantages of the present invention will become more apparent from the description, appended claims and drawings.
BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a front elevational view of the service center and moisture barrier of the present invention, partly broken away;
FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1, with a portion of the moisture barrier removed to illustrate the compressive characteristic of the moisture barrier material; the conductor illustrated in FIG. 1 is also removed from this figure for the purpose of clarity; and
FIG. 3 is a sectional view taken along line 33 of FIG. 2 which illustrates the hourglass configuration of a conductor passage and its plug.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrical service center and moisture barrier illustrated in the figures includes a service center proper equipped with a moisture barrier 12.
The service center is adapted for installation in the ground with a portion extending above the ground. The service center has, for example, a circuit breaker 14 and a plug receptacle 16 which are electrically coupled to provide switching, circuit protection and service to mobile trailer homes and the like. Electrical coupling of these elements is provided within an upper portion 18 of a housing or pedestal 20. This coupling is not shown inasmuch as it does not form a part of the invention as such and may take any number of forms, one of which, for example, includes a detachable upper cover 22 which mounts receptacle 16 and circuit breaker 14 for quick detachment from attendant current carriers in the form of bus bars.
Housing 20 is of standard construction. As such, it may be formed of any suitable material, for example, sheet metal. The housing has a rectangular cross section with an interior for the moisture barrier and circuit elements. The interior of the housing is closed by the housings front, back, side walls and covers to protect what it contains from the elements.
The intermediate portion of service center 10 includes moisture barrier 12 and a plurality of terminal blocks 24. These terminal blocks are mounted to the back of housing 20 through an insulating block 26 by means of fasteners 28. Studs 30 of the terminal blocks extend forward thereof for the attachment of bus bars 32 and 34 as by nuts 35. A conductor 36 passes through a conductor passage in the moisture barrier for its connection in the terminal blocks, the connection being in a standard manner. A removable cover 38 is attached to the balance of housing 20 by such means as wing nuts, not shown. This cover and upper cover 22 have downwardly extending flanges 40 and 42 to provide a protective skirt for the interior of the housing against the elements.
With this generalized description of the service center proper, a more detailed description of moisture barrier 12 will be presented. With reference to FIGS. 2 and 3,
the moisture barrier includes a conductor receiver portion or member 44 and a compression member 46. Conductor receiver member 44 includes a plurality of conductor passages 48. A longitudinal slit 50 connects each of these conductor passages with a surface 52 of conductor receiving member 44 for the easy installation of conductors into the conductor passages.
As is illustrated in FIG. 3, each conductor passage 48 has a generally hourglass shape which converges from either longitudinal end of conductor receiving member 44 to a throat 54 of reduced cross-sectional area. As is also illustrated in FIG. 3, a complementary, hourglass-shaped plug 56 is provided for each of these con ductor passages.
A channel-like mounting bracket 58 is provided for conductor receiving member 44. Mounting bracket 58 is attached to the back wall of housing 20 as by screws 60. A stiffener 62, which may be fabricated from any suitable material, is disposed within mounting bracket 58 on one side of conductor receiving member 44. Only one stiffener is provided to enable longitudinal expansion of the conductor receiving member when removable cover 38 and compression member 46 compress the conductor receiving member. A second channel-like mounting bracket 64 is attached to removable cover 38 as by screw fasteners 66. This mounting bracket receives compression member 46. Mounting brackets 58 and 64 have opposing walls 68 and 70, respectively (shown in FIG. 3). These opposing walls act to provide lateral stability for conductor receiving member or portion 44 and compression member or portion 46 of moisture barrier 12. Lateral stability as provided by these opposing walls may be necessary to prevent displacement of the moisture barrier members. The channel defined by the opposing walls also, of course, provides a convenient means for housing the moisture barrier.
Stiifener 62 has a plurality of cutouts 72 which open on the same side of conductor receiving portion 44 as slits 50. This provides for ease in placing conductors within conductor passages 48.
Conductor receiving portion 44 and compression portion 46 may be formed of any material which has a readily deformable, rubber-like quality. One suitable material is sponge rubber. Another suitable material is polyurethane foam. The readily compressible and deformable characteristic of such material admits to the deformation of moisture barrier material surrounding the conductor passages into intimate, moisture sealing contact with conductors passing through the conductor passages. Moreover, the compressive and deformable characteristic of such materials admits to the easy installation of cover 38 to produce this compression. The interface between conductor receiving portion 44 and compression portion '46 is also readily sealed by virtue of the deformability of the materials constituting these portions.
In use, conductors or feeders of the required number for a given installation are inserted in the appropriately placed number of conductor passages with cover 38 removed. With a large diameter conductor, such as the one illustrated in FIG. I, plug 56 is removeed from conductor passage 48. For smaller-diameter conductors it is not necessary to remove the plug, the conductor is merely inserted through slit 50 into the appropriate conductor passage. Unused conductor passages retain their plugs. After the conductors have been placed in the conductor passages and attached to their terminal blocks, cover 38 is installed on housing 20. When the cover is installed, the moisture barrier is compressed into intimate contact with the conductors passing through it. The approximate degree of compression is shown in FIG. 2 by the reduced thickness portion of conductor receiving portion 44 illustrated in that figure.
What is claimed is:
1. An improvement in combination with a service center for supplying electrical energy of the type having a housing for enclosing circuit elements and conductors, an improvement in the moisture barrier which prevents ground moisture from entering the upper portion of the housing and contacting exposed circuit elements and conductors, the improvement comprising:
(a) the moisture barrier being formed of a rubbery,
readily deformable material;
(b) a plurality of generally hourglass-shaped conductor passages within the moisture barrier for the passage of conductors into the housings upper portion;
(c) a generally hourglass-shaped plug of a rubbery, readily, deformable material disposed in each of the conductor passages, each of the plugs being removable from its associated conductor passage for accommodating a large conductor therein, and .each of the plugs and proximate moisture barrier material being operable to deform into sealing engagement with a small conductor received in such plugs associated conductor passage;
(d) a slit from an accessible surface of the moisture barrier to each conductor passage for placing a conductor therein; and
(e) means associated with the housing for compressing the moisture barrier such that the walls of its conductor passages press tightly in sealing engagement against conductors passing through them;
whereby, each conductor passage has a narrow cross section intermediate its ends to enhance a moisture seal between the wall of the conductor passage and a conductor, and, with a passage having its associated plug therein, a substantially continuous filling of such passage.
2. The improvement claimed in claim 1 wherein:
the moisture barrier includes a compression member formed of a rubbery, readily deformable material, the compression member being mounted on a removable cover of the housing in position to compress the portion of the moisture barrier having the conductor passages when the cover is installed.
3. The improvement claimed in claim 2 wherein the slits oepn at the interface between the portion of the moisture barrier having the conductor passages and the compression member. Y
4. The improvement claimed in claim 3 including a stiffener mounted to the housing on one side of the portion of the moisture barrier containing the conductor passages.
5. The improvement claimed in claim 4 including a pair of channel-shaped mounting brackets, one of the channel-shaped mounting brackets being mounted on the removable cover and receiving the compression member, the other channel-shaped mounting bracket being mounted in the housing and receiving the portion of the moisture barrier having the conductor passages and the stiffener, the opposed walls of each of the channel-shaped mounting brackets providing lateral support for the portion of the moisture barrier it receives.
6. An improved electrical service center comprising:
(a) a housing having a base adapted for placement in the ground and an upper portion for containing moisture sensitive electrical elements;
(b) a moisture barrier in the housing above the base and below the upper portion in position to prevent moisture from entering the upper portion, the moisture barrier:
(i) being fabricated from a readily deformable,
(ii) having a plurality of conductor passages from the base to the upper portion, each conductor passage being shaped like an hourglass, and
(iii) having an hourglass-shaped plug for each conductor passage which is adapted to be interfitted therein; and
(c) means associated with the housing for compressing the moisture barrier such that the walls of its conductor passages compress tightly in sealing engagement against conductors passing through them.
7. The service center claimed in claim 6 wherein:
(a) the means for compressing the moisture barrier includes a removable cover of the housing, the moisture barrier having sufficient thickness to be compressed when the cover is in place on the housing; and
(b) a slit is provided for each of the conductor passages, each slit extending from its associated c0nducductor passage through a surface of the moisture barrier which is exposed when the cover is removed, the slits providing means for placing conductors into the conductor passages.
8. The service center claimed in claim 7 wherein the moisture barrier includes a compression member formed of a rubbery, readily deformable material mounted to the removable cover in position, when the cover is installed, to compressively engage the portion of the moisture barrier having the conductor passages.
9. The electrical service center claimed in claim 8 including a pair of channel-like mounting members, one of the channel-like mounting members being carried by the removable cover and mounting the compression member, the other of the channel-like members being attached in the housing and mounting the portion of the moisture barrier having the conductor passages, the opposed walls of each of the channel-like members providing lateral support for the portion of the moisture barrier it mounts.
10. The improved electrical service center claimed in claim 9 including a stiffener interposed between the portion of the moisture barrier containing the conductor passages and the channel-like mounting bracket which mounts such portion, the stiffener having a plurality of cutouts opening towards the compression member for ease in installing conductors in the conductor passages.
References Cited UNITED STATES PATENTS 965,684 7/1910 Bierce et al. l7477 X 2,953,625 9/1960 Hasselhorn l7460 3,164,668 1/1965 Skubal l7437 X 3,435,124 3/1969 Channell 174-38 X FOREIGN PATENTS 546,309 9/ 1957 Canada.
964,695 5/1957 Germany.
724,596 2/ 1955 Great Britain.
LARAMIE E. ASKIN, Primary Examiner US. Cl. X.R.