RAIN TIGHT JUNCTION BOX

Abstract: A rain tight enclosure (10) for electrical components is formed by a base member (12) defining a termination cavity (16) surrounded by a channel (53) separated from the cavity by a flange (20) having notches (22) spaced about the periphery thereof, at least two cable passages (24) through the base opening into the cavity (16) and a cover member (14) having an integral depending portion (52) which is received in the channel (53) of the base (12). The base (12) also has at least one sealing cavity (26) and at least one strain relief cavity (28) intersecting each said cable passage (24). The base (12) and the cover (14) are provided with interengaging latching means (44) to securely hold them in an assembled condition. The notches (22) in the flange (22) allow the enclosure to breath so that water is not drawn into the enclosure by temperature changes.

Description: RAI N TIGHT JUNCTION BOX BACKGROUND OF THE I NVENTION The present invention relates to an improved rain tight enclosure for electrical terminals. Terminal blocks for use outdoors , such as for solar panel installations , must be made rain tight to prevent rain from entering and short-circuiting exposed leads inside. This is conventionally accomplished by a deformable seal , such as a pre-cut elastomeric material , a closed-cell foam, rubber O-rings, etc. These seals are discrete items of manufacture and , therefore, require assembly with a degree of precision which adds to the cost of manufacture and installation . Further, the seals are subject to misalignment and deterioration. A terminal block which would be impervious to rain and , in particular, would not allow moisture into its interior through capillary action would be a vast improvement over what is currently available. Summary of the Invention The present improved rain tight terminal block is formed by a housing member defining a terminal cavity surrounded by a peripheral channel with at least one cable passageway entering the cavity and with at least one transverse sealing recess intersecting each passage between the adjacent side and the peripheral channel . The terminal block further includes a cover with means on the housing and the cover to latchingly engage in a closed condition . The recess intersecting each cable passage has a resilient sealing member inserted therein. The member is restrained by the recess and can be penetrated by a cable inserted through the passageway. A further transverse groove in the housing receives a strain relief member. In contradistinction to the prior art, the present terminal block is not sealed per se, but can breathe since there are clearances around the mating surfaces. Because the block can breathe, it does not suck water in during changes in atmospheric pressure or during rapid heating or cooling in the weather and moisture from condensation can evaporate out. SUBSTITUTE SHEET The watertight enclosure or junction box of the present invention also comprises a box member and a cover having open peripheral channels which fit together to form an enclosed peripheral duct which prevents water from seeping into the enclosure. A gap between the outside and the duct provides an exit for any water which enters therethrough . The channels are dimensioned so that the duct is large enough to prevent filling with water before it flows out. When the box is mounted horizontally, the duct may fill with water, but a high inner wall assures that water will exit through the gap before entering the enclosure. The present invention will now be described by way of example with reference to the accompanying drawings in which : FIGURE 1 is an exploded perspective view of the subject terminal block; FIGURE 2 is a top plan view of the subject terminal block; and FIGURE 3 is a section taken along line 3-3 of Figure 2. Figure 1 is an exploded perspective view of the rain tight enclosure of the present invention. The subject rain tight terminal block 10 has a base 12 of rigid insulative material and a cover 14 of similar material . The base 12 defines a generally rectangular termination cavity 16 surrounded by a peripheral channel 18 separated by a rectangular flange or web 20 having notches 22 at the respective corners . At least one cable passage 24 extends through one side of the base 12 to open into the cavity 16. Each passage 24 is intersected by a sealing cavitv 26 and a strain relief groove 28 , the cavity and groove receiving therein , respectively, a sealing member 30 and a strain relief member 32. The base also has cover latching ears 34, 36 defining slots 38 , 40 , respectively , and can be provided with conventional mounting means (not shown) . The cover 14 is profiled to be received on the base 12 and has tine 42 which is received in slot 38 and latching member 44 which is received in groove 46 accessible through slot 48 to engage in slot 40. The latching member 44 is provided with a dimple 50 which holds the latching member in either the open or latched positions. The slot 48 is profiled to allow entry of a bladed tool , such as a screwdriver not shown) but not a fingernail or the like, to move latching member 44. Groove 46 is also provided with weep holes (not shown) to prevent water and/or ice from blocking movement of the latching member 44. The cover 14 also has an integral inwardly directed annular profile 52 , best seen in Figure 3 , which is received in the channel 18 of the base. An outwardly facing channel 53 is formed in annular profile 52 by upper and lower peripheral parallel flanges 55 and 57. The lower flange on the cover fits into the channel 18 in the base and the upper flange overlaps the outer wall leaving a slight gap providing the only opening to the otherwise enclosed duct about the periphery of the assembly. Since the profile 52 is annular and extends around the base in channel 18 , the gap extends around the entire base. This annular gap provides an exit for water which may have collected in channel 18 or the outwardly facing channel in the cover profile 52 , regardless of the orientation of the enclosure. It will be noted from Figure 3 that the profile 52 fits closely into the channel 18. The notches 22 at the corners of the flange 20 breaks the water seal which forms between the cover and base so that the cavity 16 can breathe without drawing water into the cavity. Thus , changes in temperatures will not cause a wicking action of moisture into the cavity. It is also possible to form the cover 14 with an umbilical (not shown) to keep it in close proximity to the base 12 when the terminal block is open . The cover 14 has been shown with a surface profile which allows it to be conveniently gripped should access from the sides of the terminal block not be available because of other blocks or structure. The cover 14 could be further profiled to receive labels bearing polarity and/or color codes or these could be molded into the upper surface of the cover. The cable sealing member 30 is a substantially rectilinear member of resilient material , such as soft, low compression set, closed cell silicon rubber, which is received in the cavity 26 and restrained thereby. Unlike most prior art seals , the resilient material does not have any prepunched holes or openings to that no play is required if only one cable is inserted . The material is such that the conductors 54 and insulation 56 of the cable 58 can penetrate the sealing member 30 as best seen in Figure 3 , and in so penetrating carry some of the resilient material along the cable periphery to completely fill the passage 24 and even enter the cavity 16. Thus, a total cable seal Is provided. Also, it should be noted that should the cable be withdrawn from the housing , the resilient material will effectively close off the passage 24 as it is only displaced by the cable's passage and not destroyed thereby. The strain relief member 32 shown is a flat rigid member with a triangular configuration , each corner of which is profiled by recesses 60, 62 , 64. These recesses are of different sizes so that a wide range of cable diameters can be accommodated in the present terminal block and secured therein by a single strain relief member 32. The terminal 66 can best be understood from Figures 2 and 3. The cavity 16 is provided with a pair of wire guiding walls 68 , 70. A plate 72 is mounted in the cavity 16 between walls 68 , 70 supported by bosses 74, 76 and engaging shoulder 78. A self threading screw 80 , which is also preferably self captivating is received in tapped passage 82 of plate 72 and carries a profiled square lock washer 84. The walls 68 , 70 serve to guide the wires 54 of cables 56 , 58 to each side of the terminal 66 , to prevent rotation of the lockwasher 84 as the screw 80 is tightened , and to prevent spreading of the wires 54 of the cables 56 , 58.

Claims: CLAIMS: 1 . A water tight enclosure ( 10) for electrical components comprising: a base ( 12) of integral insulative material defining a central termination cavity (16) ; a cover (14) profiled to be received on said base (12) ; means (38 , 40 , 42 , 44) to latchingly engage said cover (14) on said base (12) ; cable passages (24) extending through the base ( 12) into the termination cavity (16) ; means to seal cables (58) extending therethrough; and cable termination means (72 , 80 , 84) in the termination cavity (16) ; characterized in that said base member ( 12) and said cover (14) have a mating cross sectional geometry which diverts water flow away from said termination cavity ( 16) . 2. The water tight enclosure (10) of claim 1 wherein the mating cross sectional geometry comprises a peripheral channel (18) in the base ( 1 2) and an annular profile (52) having an outwardly facing channel (53) in the cover ( 14) , the first channel (18) being separated from the termination cavity (16) by a flange (20) , the cover (14) and the flange (20) being dimensioned to allow air movement into and out of said termination cavity (16) . 3. The water tight enclosure according to claim 2 wherein said flange (20) has at least one notch (22) breaking up any water flow pattern to prevent drawing of water into said termination cavity ( 16) with pressure and/or temperature changes. 4. The water tight enclosure of claim 3 wherein said sealing means comprises a body (30) of sealant material cavity , said sealing material being penetrated by a cable driven therethrough forming an annular seal thereabout. 5. The water tight enclosure of claim 4 wherein said body (30) of sealing material is received within a sealing cavity (26) intersecting a plurality of cable passages (24) . 6. The water tight enclosure of claim 5 wherein the termination means (80 , 84) comprises a plate (84) mounted in said termination cavity (1 6) having a self threading , self captivating screw (80) therein , and a profiled lock washer (84) on said screw (80) . 7. The water tight enclosure of claim 6 further comprising walls (68 , 70) in said termination cavity (16) serving to guide cables (58) to said screw (80) . 8. The water tight enclosure of claim 2 wherein the outwardly facing channel (53) is formed by upper and lower peripheral parallel flanges (55 , 57) , the upper flange overlapping the body (12) leaving a gap about the periphery of the cover (14) communicating with the outwardly facing channel (53) .

Inventors: FELDMAN STEVEN, FELDMAN, STEVEN
Applicants: AMP INC, AMP INCORPORATED
Application year: 1985
Main classification: H02G3
IPC codes: H02G3, H05K5, H05K7