CA1089968A - Clamping device for an electrical outlet box made of molded plastic material - Google Patents
Clamping device for an electrical outlet box made of molded plastic materialInfo
- Publication number
- CA1089968A CA1089968A CA297,297A CA297297A CA1089968A CA 1089968 A CA1089968 A CA 1089968A CA 297297 A CA297297 A CA 297297A CA 1089968 A CA1089968 A CA 1089968A
- Authority
- CA
- Canada
- Prior art keywords
- outlet box
- slide
- box
- electrical outlet
- integrally molded
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
- H02G3/02—Details
- H02G3/08—Distribution boxes; Connection or junction boxes
- H02G3/081—Bases, casings or covers
- H02G3/083—Inlets
- H02G3/085—Inlets including knock-out or tear-out sections
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Connection Or Junction Boxes (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A clamping device for an electrical outlet box made of molded plastic material is disclosed. The clamping device compri-ses a plastic slide, a slide guide integrally molded into the side walls of the outlet box, a rib integrally molded into the bottom of the outlet box adjacent a hole in the wall of the outlet box and at least one buttress groove in the slide meshing with a tooth in the wall of the outlet box for locking the slide against a cable entering the outlet box through the hole when the slide is pushed so that it impinges on the cable causing it to kink slightly over the above mentioned rib.
A clamping device for an electrical outlet box made of molded plastic material is disclosed. The clamping device compri-ses a plastic slide, a slide guide integrally molded into the side walls of the outlet box, a rib integrally molded into the bottom of the outlet box adjacent a hole in the wall of the outlet box and at least one buttress groove in the slide meshing with a tooth in the wall of the outlet box for locking the slide against a cable entering the outlet box through the hole when the slide is pushed so that it impinges on the cable causing it to kink slightly over the above mentioned rib.
Description
~ ~9 ~ ~
This invention relates to a clamping device for an elec-trical outlet box made of molded plastic material.
One of the biggest problems in designing an electrical outlet box that can be injection molded from polymeric material is the clamping of the cable entering the outlet box so as to meet the pull-out tests of the electrical code. Prior solutions to -this clamping problem have been partly metallic, using screws, rivets or similar mechanical devices to effect clamping of the cable. The only all plastic clamping device which applicant is aware of is a separate clamp that does the clamping by itself without cooperation with the outlet box except that the device is ' made to fit in-to the outlet box knockout hole.
It is the object of the present invention to provide a alampin~ d~vice tha-t meets the pull-out tests of the electrical cod~, can be injection molded from plastic materials and is mainl,y part of the outlet box.
It is a further object of the present invention to pro-vide a clampinq device that uses no screws or other mechanical fastening devices other than the operating parts built into the ~n clamping device itself.
~ he clamping device, in accordance with the invention, comprises a plastic slide, a slide guide in-tegrally moldecl :Lnto -kh~ wall9 of the outlet box above each hole through wh:Lch the cable qn~r~, ~ xlb in-tegrally molded into the bottom of the ou-tlet box ad~ nt each hole, at least one buttress groove integrally molded in~a the 9ur~ace oE the slide acinq the wall of the ou-tlet box and a -tqoth inteqrally molded into the wall oE the outlet box and meshin~ with the buttress groove for locking the slide against the ! cable when the slide is pushed so that it impinges on the cable causing it to kink slightly over the rib built into the bottom of the outlet box. ' The slide preferably have two spaced legs adapted to : .
3~
contact the cable, one on each side of the above mentioned rib The outlet bo~ is provided with a grounding device for attachment of the ground wire of the cable to the outlet box.
The grounding device consists of at least one molded plastic post integral with the bottom of the outlet box, an electrically conductive grounding lug secured to such post and at least one self tapping grounding screw threaded through the grounding lug.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
Figure 1 illustrates a section view through a corner of a rectangular outlet box and parallel to the bottom of the j box;
Figure 2 illus-trates a section view taken along lines
This invention relates to a clamping device for an elec-trical outlet box made of molded plastic material.
One of the biggest problems in designing an electrical outlet box that can be injection molded from polymeric material is the clamping of the cable entering the outlet box so as to meet the pull-out tests of the electrical code. Prior solutions to -this clamping problem have been partly metallic, using screws, rivets or similar mechanical devices to effect clamping of the cable. The only all plastic clamping device which applicant is aware of is a separate clamp that does the clamping by itself without cooperation with the outlet box except that the device is ' made to fit in-to the outlet box knockout hole.
It is the object of the present invention to provide a alampin~ d~vice tha-t meets the pull-out tests of the electrical cod~, can be injection molded from plastic materials and is mainl,y part of the outlet box.
It is a further object of the present invention to pro-vide a clampinq device that uses no screws or other mechanical fastening devices other than the operating parts built into the ~n clamping device itself.
~ he clamping device, in accordance with the invention, comprises a plastic slide, a slide guide in-tegrally moldecl :Lnto -kh~ wall9 of the outlet box above each hole through wh:Lch the cable qn~r~, ~ xlb in-tegrally molded into the bottom of the ou-tlet box ad~ nt each hole, at least one buttress groove integrally molded in~a the 9ur~ace oE the slide acinq the wall of the ou-tlet box and a -tqoth inteqrally molded into the wall oE the outlet box and meshin~ with the buttress groove for locking the slide against the ! cable when the slide is pushed so that it impinges on the cable causing it to kink slightly over the rib built into the bottom of the outlet box. ' The slide preferably have two spaced legs adapted to : .
3~
contact the cable, one on each side of the above mentioned rib The outlet bo~ is provided with a grounding device for attachment of the ground wire of the cable to the outlet box.
The grounding device consists of at least one molded plastic post integral with the bottom of the outlet box, an electrically conductive grounding lug secured to such post and at least one self tapping grounding screw threaded through the grounding lug.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
Figure 1 illustrates a section view through a corner of a rectangular outlet box and parallel to the bottom of the j box;
Figure 2 illus-trates a section view taken along lines
2-2 oE Figure 1;
Figure 3 illustrates a section view taken along lines
Figure 3 illustrates a section view taken along lines
3-3 of Figure l;
Figure ~ illustrates a section view as in Figure 3 with the slide of the grounding device removed and before removal of the knock out portion of the hole through which the cable is in-~0 serted into the outlet box; and ``~
Figures 5 and 6 illustrate side and top views of a ~rounding device for attachment oE the ground w.ire of the cable.
Referrin~ to Figures 1 to 3, there is shown a clamping device 10 for use in an outle-t box 1~ oE the rectan~ular type ancl m~dc oE extruded plastic material. This type of box generally has a bottom wall and opposed side and end walls. The end walls are usually provided with two knockout holes at each end. It is to be understood, however, that the clamping devices may be used with other types of outlet boxes.
The clamping device is composed of a slide 14 that fits into guides 16 which are integrally molded in the four corners of the box. The slide 14 contains a number of buttress type grooves ~ 2 -. .
39~
18 on one side. This groved side faces the wall of the box when inserted lnto guides 16. A single, lightly flexible tooth 20, molded integrally on the box with the edge facing in, meshes with one of -the grooves on the slide 14. The surfaces of both the gro-ves on the slide 14 and tooth 20 were so designed as to provide an undirectional Eree slide and, in this case, in the direc-tion to-wards the bottom of the box.
When slide 14 is pushed all the way down against cable 22 and tooth 20 is locked securely in place, the first clamping action is achieved.
The second and final clamping action is achieved by j sp~cially designed leg sec-tions 24 and 26 of the slide 14 and a wedge shaped rib 28 molded integrally to the bottom of the box and positioned in such a manner as to be exactly between legs 24 and 26 when slide 14 is locked in place by tooth 20. Now, when a force F is applied on the cable 22, it creates a reaction force at point A on slide 14 and a moment around ~ also on slide 14.
~ooth 20 is designed as to sustain the maximum vertical compo-nen~s of these reaction ~orces. With too-th 20 locked at point C, 20 any Eorce F will always create a larger downward reaction force at point B -tha-t will keep i-t ~rom getting loose. In short, -the me-ahanism uses the applied force itself in locking Eirmer -the cable ln the Eirst pasi-tion~
Le~s 24 and 26 are generally of inverted right triangu-lar shape wi-th their hypotenuse facing each other. Tooth 20 is ~l~o o~ ~encrally -triangular section.
A semi-circular groove 30 is provlded on the back of the slide twhere it touches the inside wall of the outlet box) through which a standard flat screw driver or any suitable -tool can be in-serted to push back tooth 20 freeiny the slide. A rib 32 is mol~ded on the front end of the slide to allow a person, using his other free hand, to pull it up freeing the cable.
i8 Figure 4 illustra-tes a cross-sectional view of the out-let box as in Figure 3 prior to insertion of the slide 14 and re-moval of the knockout portion 34 in front of the hole through which the cable 22 is inserted. It will be seen that removal oE portion 34 will leave the tooth 20 which cooperates with the grooves 18 of the slide to secure initially the cable in the outlet box.
Figures 5 and 6 illustrate an embodiment of a grounding device in accordance with the invention. The grounding device in-cludes a metal grounding lug 36, three molded plastic parts 38, two grounding screws 40 and a stranded conductor 42. The groun-ding lug 36 is a flat metal strip with a "~" projection on one side and three punched holes located along its length. The two O~I~Si~ holes are fi-tted with self tapping screws ~0. The "T"
p~ ection i5 bent to form a crimped fit attachment 44 oE the 9tranded conductor 42. The stranded conductor is used to connect an electrical device to the grounding lug 36. The -three molded posts 38 are spaced so that their centres correspond with the cen-tres of the three holes in the metal grounding lug 36. The two exterior posts are hollow to allow for the grounding screws. The ~4 cqntre post is solid and is made so that when the metal grounding lug is placed on it, a part of the post remains above the top sur-ace of the lug. The plastic that remains above the -top surEace o~ the lu~ is ultrasonically staked Eorming a lip 46 which pre-ven~s the l~lg from coming back oE~. The posts have suEEicient he~ht to pxeven-t protrusion of the screws through the bottom oE
th~ bo~ which leaves a smooth Elat ex-terior surEace for be-tter in~ llation characteristics.
It will be clearly seen that the above disclosed clam-ping device uses no screws or any mechanical fastening devices other than the ope~ating parts built into the clamping device it-self~ With this new device, simply by molding the plastic slide unit and sliding it into the molded outlet box receiving guide,
Figure ~ illustrates a section view as in Figure 3 with the slide of the grounding device removed and before removal of the knock out portion of the hole through which the cable is in-~0 serted into the outlet box; and ``~
Figures 5 and 6 illustrate side and top views of a ~rounding device for attachment oE the ground w.ire of the cable.
Referrin~ to Figures 1 to 3, there is shown a clamping device 10 for use in an outle-t box 1~ oE the rectan~ular type ancl m~dc oE extruded plastic material. This type of box generally has a bottom wall and opposed side and end walls. The end walls are usually provided with two knockout holes at each end. It is to be understood, however, that the clamping devices may be used with other types of outlet boxes.
The clamping device is composed of a slide 14 that fits into guides 16 which are integrally molded in the four corners of the box. The slide 14 contains a number of buttress type grooves ~ 2 -. .
39~
18 on one side. This groved side faces the wall of the box when inserted lnto guides 16. A single, lightly flexible tooth 20, molded integrally on the box with the edge facing in, meshes with one of -the grooves on the slide 14. The surfaces of both the gro-ves on the slide 14 and tooth 20 were so designed as to provide an undirectional Eree slide and, in this case, in the direc-tion to-wards the bottom of the box.
When slide 14 is pushed all the way down against cable 22 and tooth 20 is locked securely in place, the first clamping action is achieved.
The second and final clamping action is achieved by j sp~cially designed leg sec-tions 24 and 26 of the slide 14 and a wedge shaped rib 28 molded integrally to the bottom of the box and positioned in such a manner as to be exactly between legs 24 and 26 when slide 14 is locked in place by tooth 20. Now, when a force F is applied on the cable 22, it creates a reaction force at point A on slide 14 and a moment around ~ also on slide 14.
~ooth 20 is designed as to sustain the maximum vertical compo-nen~s of these reaction ~orces. With too-th 20 locked at point C, 20 any Eorce F will always create a larger downward reaction force at point B -tha-t will keep i-t ~rom getting loose. In short, -the me-ahanism uses the applied force itself in locking Eirmer -the cable ln the Eirst pasi-tion~
Le~s 24 and 26 are generally of inverted right triangu-lar shape wi-th their hypotenuse facing each other. Tooth 20 is ~l~o o~ ~encrally -triangular section.
A semi-circular groove 30 is provlded on the back of the slide twhere it touches the inside wall of the outlet box) through which a standard flat screw driver or any suitable -tool can be in-serted to push back tooth 20 freeiny the slide. A rib 32 is mol~ded on the front end of the slide to allow a person, using his other free hand, to pull it up freeing the cable.
i8 Figure 4 illustra-tes a cross-sectional view of the out-let box as in Figure 3 prior to insertion of the slide 14 and re-moval of the knockout portion 34 in front of the hole through which the cable 22 is inserted. It will be seen that removal oE portion 34 will leave the tooth 20 which cooperates with the grooves 18 of the slide to secure initially the cable in the outlet box.
Figures 5 and 6 illustrate an embodiment of a grounding device in accordance with the invention. The grounding device in-cludes a metal grounding lug 36, three molded plastic parts 38, two grounding screws 40 and a stranded conductor 42. The groun-ding lug 36 is a flat metal strip with a "~" projection on one side and three punched holes located along its length. The two O~I~Si~ holes are fi-tted with self tapping screws ~0. The "T"
p~ ection i5 bent to form a crimped fit attachment 44 oE the 9tranded conductor 42. The stranded conductor is used to connect an electrical device to the grounding lug 36. The -three molded posts 38 are spaced so that their centres correspond with the cen-tres of the three holes in the metal grounding lug 36. The two exterior posts are hollow to allow for the grounding screws. The ~4 cqntre post is solid and is made so that when the metal grounding lug is placed on it, a part of the post remains above the top sur-ace of the lug. The plastic that remains above the -top surEace o~ the lu~ is ultrasonically staked Eorming a lip 46 which pre-ven~s the l~lg from coming back oE~. The posts have suEEicient he~ht to pxeven-t protrusion of the screws through the bottom oE
th~ bo~ which leaves a smooth Elat ex-terior surEace for be-tter in~ llation characteristics.
It will be clearly seen that the above disclosed clam-ping device uses no screws or any mechanical fastening devices other than the ope~ating parts built into the clamping device it-self~ With this new device, simply by molding the plastic slide unit and sliding it into the molded outlet box receiving guide,
- 4 -"3~
the outlet box becomes a one piece unit which simply requires the cable to be inserted into it and the clamping device tightened through pushing the slide so that it impinges on the cable causing it to kink slightly over the rib built into the bottom of the outlet box. The clamping device in accordance with the inven-tion is incorporated around and an integral part of the hole through which the cable is inserted, not an add-on device such as some of the known clamping devices.
Although the invention has been disclosed with reference to a preferred embodiment, it is to be understood that various modifications may be made to such embodiment within the scope of the invention. Indeed, the clamping device may be used with any type of outlet boxes. The shape of the slide may vary as well as the number of legs provided on the slide for securing the cable -~o the outlet box. The invention is to be limited by the scope of the claims only.
, ~ `
the outlet box becomes a one piece unit which simply requires the cable to be inserted into it and the clamping device tightened through pushing the slide so that it impinges on the cable causing it to kink slightly over the rib built into the bottom of the outlet box. The clamping device in accordance with the inven-tion is incorporated around and an integral part of the hole through which the cable is inserted, not an add-on device such as some of the known clamping devices.
Although the invention has been disclosed with reference to a preferred embodiment, it is to be understood that various modifications may be made to such embodiment within the scope of the invention. Indeed, the clamping device may be used with any type of outlet boxes. The shape of the slide may vary as well as the number of legs provided on the slide for securing the cable -~o the outlet box. The invention is to be limited by the scope of the claims only.
, ~ `
Claims (7)
1. In an electrical outlet box made of molded plastic material and having a bottom and opposed side walls, a clamping device for securing a cable entering the box through a hole in at least one of the side walls of the box adjacent the bottom thereof comprising:
a) a plastic slide;
b) a slide guide integrally molded into at least one of the side walls of the electrical outlet box inside the elec-trical outlet box;
c) a rib integrally molded into the bottom of the outlet box adjacent said hole; and d) at least one buttress groove integrally molded into the surface of the slide facing the side wall of the outlet box;
and e) a tooth integrally molded into the wall of the out-let box and meshing with the buttress groove for locking said slide against the wire when the slide is pushed so that it impin-ges on the cable causing it to kink slightly over said rib.
a) a plastic slide;
b) a slide guide integrally molded into at least one of the side walls of the electrical outlet box inside the elec-trical outlet box;
c) a rib integrally molded into the bottom of the outlet box adjacent said hole; and d) at least one buttress groove integrally molded into the surface of the slide facing the side wall of the outlet box;
and e) a tooth integrally molded into the wall of the out-let box and meshing with the buttress groove for locking said slide against the wire when the slide is pushed so that it impin-ges on the cable causing it to kink slightly over said rib.
2. An electrical outlet box as defined in claim 1, wherein said slide has two spaced legs adapted to contact the cable, one on each side of said rib.
3. An electrical outlet box as defined in claim 2, wherein said rib is wedge-shaped.
4. An electrical outlet box as defined in claim 1, further comprising a grounding device for the ground wire of the cable entering the outlet box including a post integrally molded into the bottom of the outlet box, an electrically conductive grounding lug secured to said post and at least one grounding screw threaded through said grounding lug.
5. An electrical outlet box as defined in claim 4, wherein at least one additional hollow post is integrally molded into the bottom of the outlet box in line with said screw, and wherein both posts are long enough to prevent protrusion of the screw from the rear of the outlet box through the hollow post.
6. An electrical outlet box as defined in claim 5, wherein two hollow posts are provided one on each side of the first mentioned post to which the grounding lug is secured.
7. An electrical outlet box as defined in claim 6, wherein a conductor is attached to said grounding lug for groun-ding an electrical device mounted in the opening of the outlet box.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,297A CA1089968A (en) | 1978-02-20 | 1978-02-20 | Clamping device for an electrical outlet box made of molded plastic material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA297,297A CA1089968A (en) | 1978-02-20 | 1978-02-20 | Clamping device for an electrical outlet box made of molded plastic material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1089968A true CA1089968A (en) | 1980-11-18 |
Family
ID=4110819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA297,297A Expired CA1089968A (en) | 1978-02-20 | 1978-02-20 | Clamping device for an electrical outlet box made of molded plastic material |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1089968A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0531172A1 (en) * | 1991-09-06 | 1993-03-10 | THOMAS & BETTS CORPORATION | An enclosure for an electrical terminal block including barrier means for a cable entry opening |
-
1978
- 1978-02-20 CA CA297,297A patent/CA1089968A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5254808A (en) * | 1990-07-11 | 1993-10-19 | Thomas & Betts Corporation | Enclosure for an electrical terminal block including barrier means for a cable entry opening |
| EP0531172A1 (en) * | 1991-09-06 | 1993-03-10 | THOMAS & BETTS CORPORATION | An enclosure for an electrical terminal block including barrier means for a cable entry opening |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |