Tamper resistant receptacle with inclined compression spring

Abstract

A tamper-resistant receptacle having a shutter member biased in the closed position by spring members in inclined tracks on a housing. Shutter travels in the tracks to provide lateral and vertical movement of the shutter member to provide clearance to the hot and neutral contacts of a receptacle upon simultaneous insertion of the hot and neutral blades of an electrical plug causing a camming action to compress a medial spring and compression of the lateral spring members to allow the shutter member to enter and travel the length of the tracks.

Description

TAMPER RESISTANT RECEPTACLE WITH INCLINED COMPRESSION SPRINGCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No 63 / 670,403, filed July 12, 2024, the entire contents of which is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates to tamper resistant electrical receptacles. More particularly, the present disclosure relates to tamper resistant electrical receptacles using an inclined spring(s).BACKGROUND

[0003] Tamper resistant receptacles are known in the art. “Tamper Resistant” or “TR” receptacles refers to a type of electrical wiring device, such as a household duplex electrical receptacle, equipped with means for physically blocking access to the electrical contacts which lie below the hot and neutral plug blade openings in the faceplate of the receptacle unless simultaneous force is exerted upon both the hot and neutral plug blade openings at the same time. Currently, NEC Code 406.11 et seq. and other regulatory requirements provide that not only must the outlet openings remain blocked unless force is applied to both openings at the same time, but also that any foreign object 1 / 32 inch or larger, must be prevented from bypassing the blocking member of a plug opening. All new construction and major renovations are mandated to by code to use TR receptacles.

[0004] As will be appreciated, these code requirements were enacted in response to the all-to-often tragic phenomena of a curious child inserting a conductive material, such as a paper clip or small toy, into either the hot or neutral plug blade opening of a receptacle faceplate and contacting the live hot or neutral electrical contact resulting in electrical shock, burns, or even death.

[0005] In meeting the code standard and providing the level of protection sought from these devices, the art has gravitated towards a configuration of receptacles utilizing cooperating shutter members to block access beyond the faceplate openings of the outlet. Specifically, to ensure that force directed into only one of the two blade openings is prevented from reaching the electrical contact that lies beneath, a sliding shutter mechanism is spring-biased into a position blocking (or “shuttering”) the blade opening from underneath the faceplate. The shutter physically prevents an object entering the blade opening from reaching the electrical contact below that shutter. In order to allow the shutter of a respective blade opening to be uncovered, the spring-bias must be overcome by a camming action caused by the other plug blade during insertion in the other blade opening.

[0006] To this end, the most common prior art configuration of a TR receptacle includes a shutter assembly comprising a pair of cooperating shutters. Each of the shutters includes a blocking portion positioned below a respective one of the blade openings blocking access to the contacts. Each of the shutters also includes a cam portion that extends to the opposite blade opening that receives contact from a plug blade and translates the vertical force of a plug blade and camming action into a lateral sliding displacement of the blocking portion. Thus, force by vertical insertion of a plug-blade on the neutral blade opening will move the shutter from obstructing access to the electrical contact below the hot blade opening, and vice versa.

[0007] Specifically, for example, during insertion of a plug, the neutral blade tine will cam against and past the shutter cam surface forcing the shutter cam arm to move laterally, thereby overcoming the spring bias of the shutter and causing the hot blade shutter blocking portion to slide into a position away from and revealing the electrical contact beneath the hot blade opening. Likewise, force on the hot blade opening will contact the cam surface and allow the blade to cam past and move the arm and compress the spring to move the shutter blocking portion that covers the neutral blade opening out of the way.

[0008] As will be appreciated, with this configuration, when a child tries to insert a toy into either opening of the outlet, the blocking portion of the shutter remains immobile from the spring bias of the opposite shutter and prevents the child from reaching the electricalcontact. However, when both blades of an electrical plug contact the shutters simultaneously, the simultaneous force and camming action allows both blades to continue their downward insertion by simultaneously sliding respective shutter blocking portions laterally out of the way of the electrical contacts of the opposite shutter until the blades cam past the shutters and are able to properly “plug in” to the outlet's internal face contacts.

[0009] Existing prior art TR receptacle designs and their operational details are available in U.S. Pat. No. 4,379,607 to Bowden, Jr.; U.S. Pat. No. 7,645,148 to Carbone et aL; and U.S. Publ. No. 2013 / 0295788 to Baldwin, et al. and the references cited therein.

[0010] The proliferation of these important safety devices has led to an appreciation of the issues affecting their effective life span and cost. A presently appreciated issue recognized by the present inventor stems from the translation of the vertical force of the plug blade into lateral movement of the shutters. In most prior art shutter assemblies, there is no way to use the combined force of the insertion plug blades to overcome a spring bias. Rather, each plug blade opening and shutter operates against its own spring bias independently. Over time, the point of contact for the plug blades on each shutter may deform to the point that so much additional force is needed to slide the shutter open that the device is no longer deemed operable. Another issue appreciated by the present inventor stems from realization that most prior art receptacles need to use a shutter housing component with mounted pairs of shutter members arranged therein to effectuate the safety features of the sliding shutters. Having to deploy an entire sub-housing comprising numerous pieces beneath the faceplate of an outlet may be a significant cost increase.

[0011] The foregoing underscores some of the problems associated with conventional TR receptacles. Furthermore, the foregoing highlights the long-felt, yet unresolved need in the art for a TR receptacle that may extend the useful life of the device. Moreover, the forgoing highlights the long-felt, yet unresolved need in the art for a TR receptacle that has an extended service life at a reasonable cost by using fewer and uncomplicated constituent parts.SUMMARY

[0012] Various examples of the present disclosure can overcome various of the aforementioned and other disadvantages associated with known TR receptacles and offer new advantages as well.

[0013] According to one aspect of various examples of the present disclosure there is provided a tamper-resistant receptacle sub-assembly comprising a body having a bottom surface, a pair of opposing side walls, and an open top; a pair of inclined guide rails on each of said opposing side walls defining a respective track; a spring member disposed in each respective track; a medial spring member; a cam body in contact with said medial spring member; a shutter member disposed in said open top; with said shutter member being configured to travel in said tracks to move said shutter.

[0014] In some forms, the shutter member includes a pair of lateral shoulder members in contact and configured for traveling in said tracks with simultaneous insertion of both the hot and neutral blades of an electrical plug.

[0015] In some forms, the shutter member includes at least one blade opening, whereby lateral movement of said shutter moves said blade opening into a position for allowing a blade to be inserted into said sub-assembly.

[0016] In a presently preferred example the tamper-resistant receptacle sub-assembly has a shutter member that includes a hot blade blocking surface, a neutral blade blocking surface, and a hot blade opening; and also includes a cam body for moving a medial spring and a cam surface; whereby vertical force on both of said hot blade blocking surface and said neutral blocking surface of the shutter causes said shutter to move vertically and laterally through travel along diagonal tracks to allow a hot blade and a neutral blade of an electrical plug to enter said sub-assembly.

[0017] In some forms, the cam surface is curved and the cam block moves laterally by camming force applied vertically to said cam surface to overcome a bias of the medial spring member.

[0018] In a preferred example, the tamper-resistant receptacle sub-assembly is configured such that simultaneous insertion of a hot plug blade and a neutral plug blade causes simultaneous compression of a medial spring and lateral spring members to cause vertical and lateral movement of the shutter.

[0019] In another form, there is a tamper-resistant receptacle sub-assembly that includes a body with a bottom surface, a first side wall perpendicular to the bottom surface, a second side wall parallel to the first side wall, and an open top. First inclined guide rails extend along the first side wall and define a first track. A medial spring member is coupled between the first side wall and a cam body. A shutter member is disposed in the open top. A spring member is disposed in the first track and is connected to the shutter member. The shutter member can travel in the first track to move said shutter member toward the bottom surface against a bias of the spring member.

[0020] In another form, there is a tamper-resistant receptacle sub-assembly that includes a body with a bottom surface, a first side wall perpendicular to the bottom surface, a second side wall parallel to the first side wall, and an open top. First inclined guide rails extend along the first side wall and define a first track. A medial spring member is coupled between the second side wall and a cam body. A shutter member is disposed in the open top. A spring member is disposed in the first track and is connected to the shutter member. The shutter member can travel in the first track to move said shutter member toward the bottom surface against a bias of the spring member

[0021] The disclosure herein should become evident to a person of ordinary skill in the art given the following enabling description and drawings. The drawings are for illustration purposes only and are not drawn to scale unless otherwise indicated. The drawings are not intended to limit the scope of the disclosure. The following enabling disclosure is directed to one of ordinary skill in the art and presupposes that those aspects within the ability of the ordinarily skilled artisan are understood and appreciated.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Various aspects and advantageous features of the present disclosure will become more apparent to those of ordinary skill when described in the detailed description of preferred examples and reference to the accompany drawing wherein:

[0023] FIG. 1 is an elevated exploded perspective view of an example of a TR subassembly according to some aspect of the present disclosure.

[0024] FIG. 2 is a top view of the exploded view of FIG. 1 .

[0025] FIG. 3 is a bottom view of the housing body of FIG. 1 .

[0026] FIG. 4 is a top view of the housing body of FIG. 3.

[0027] FIG. 5 is an elevated perspective view of the shutter member of FIG. 1 .

[0028] FIG. 6 is a bottom perspective view of the shutter member of FIG. 5.

[0029] FIG. 7 is a front elevated perspective view of the cam block of FIG. 1 .

[0030] FIG. 8 is a top perspective view of a partially assembled TR sub-assembly of the TR sub-assembly of FIG. 1 showing the body, cam body and spring members in an assembled position.

[0031] FIGS. 9A-C are cross-sectional views of a 15-Amp plug at the start of insertion into a 15-Amp TR sub-assembly.

[0032] FIGS. 10A-C are cross-sectional views of a 15-Amp plug at partial insertion into a 15-Amp TR sub-assembly.

[0033] FIGS. 1 1 A-1 1 C are cross-sectional views of a 15-Amp plug at full insertion into a 15-Amp sub-assembly.

[0034] FIGS. 12A-B are cross-sectional views of a 20-Amp plug at the start of insertion into a 20-Amp TR sub-assembly.

[0035] FIGS. 13A-B are cross-sectional views of a 20-Amp plug at partial insertion into a 20-Amp TR sub-assembly.

[0036] FIGS. 14A-B are cross-sectional view of a 20-Amp plug at full insertion into a 20-Amp sub-assembly.DETAILED DESCRIPTIONS

[0037] The Figures depict a presently preferred example of a tamper-resistant receptacle sub-assembly for use in a TR receptacle. As depicted, the example is configured for use as a tamper-resistant sub-assembly for use with a 15-Amp or 20-Amp receptacle adapted for receipt of a two-prong or three-prong plug member. However, one of ordinary skill in the art armed with the present specification will readily appreciate that the teachings of the present disclosure may be adapted for any specific type of TR device through routine experimentation, including duplex receptacles, electrical cords, receptacles with USB ports, receptacles with circular or other geometries for the face or prongs, etc.

[0038] Turning back to the Figures, a TR receptacle (not shown) has a tamperresistant receptacle sub-assembly 10 having a housing 20 and a shutter member 40. Disposed in the housing are a cam block 60, a medial helical spring 70, and a pair of lateral helical springs 80A, 80B.

[0039] The housing 20 includes a plastic body 21 having a planar bottom surface 22, an open top 23, and a pair of upwardly extending sides 24A, 24B. In some forms, the bottom surface 22 is generally rectangular and includes a first rectangular opening 25 for allowing passage of an electrical plug hot prong or blade 101 to pass through the bottom 22 of body 21 to engage with the hot electrical contact of a receptacle. The bottom surface 22 also includes a generally T-shaped opening 26 configured for allowing passage of an electrical plug neutral prong or blade 102 to pass through the bottom 22 of the body 21 to engage with the neutral contact of a receptacle. The T-shape includes a parallel opening 27 for 15-Amp plugs and a perpendicular opening 28 for 20-Amp plugs. In some forms, the T-shaped opening includes a second perpendicular opening 29 that serves as clearance for the medial spring 70.

[0040] Upwardly extending sides 24A, 24B each define a pair of corresponding angled rails 30A, 30B that define a respective spring track 31 A, 31 B. In its simplest form, the rails and spring tracks are integral with the sides as part of a singular molded body. At the bottom of the tracks 31 A, 31 B are extended posts 32A, 32B which serve as spring seats or mounts for each of a respective one of the lateral helical springs 80A, 80B. In some forms, the tracks 31 A, 31 B sit at an angle of between 20 and 80 degrees from vertical. In some forms, the angle is about 45 degrees. As elaborated on below, the angle of the of tracks depends on the amount of lateral clearance that is required (and amount of vertical distance available to descend) for a plug blade to be inserted and reach the electrical contact for a given or intended configuration and form factor of the housing.

[0041] In some forms, the neutral end of housing body 21 includes a solid portion 36 on the inside wall of one of the upwardly extending sides 24A and an opposing spring post 37 for mounting a spring on the opposite inside wall of the other upwardly extending side 24B.

[0042] In some forms, disposed in housing 20 and positioned adjacent to the solid portion 36 is a cam block 60 that serves as a ram for the medial spring member 70. Asdepicted, in this example, cam block 60 includes a flat front face 61 with a spring holding post 62 for the medial spring member 70, and a back face 63 with a curved configuration defining a camming surface 64 for creating lateral movement to move block to compress the spring member 70 against the post 37 of the sidewall as will be described in more detail below.

[0043] Disposed in the open end 23 of the housing 20 is a shutter member 40. The shutter member 40 is sized and configured to sit below the hot and neutral plug openings in the face of a TR device. In the depicted example, the shutter 40 is a rectangular, generally flat unitary piece of molded plastic or like material. The shutter 40 has a top surface 41 that includes a planar hot blade blocking surface 42 and a planar neutral blade blocking surface 43. Disposed behind the hot blade blocking surface 42 is a hot blade opening 44 configured for receiving the hot blade 101 of an electrical plug 100. The shutter 40 also defines a downwardly extending hot end flange 46, and a downwardly neutral end flange 47. Extending from an upper area of neutral end flange 47 and beyond its interior is a block stop 48 disposed in a cut out area 49 of neutral end flange 47.

[0044] The shutter 40 on its underside 50 includes first and second lateral spring holsters 51 A, 51 B. Each spring holster 51 A, 51 B includes an angular shoulder 52A, 52B with an open interior 53A, 53B having a spring post 54A, 54B defined therein. The holsters 51 A, 51 B are sized and angled to travel within the rails 30A, 30B of tracks 31 A, 31 B. Each holster holds a first end of a respective lateral spring member 80A, 80B with the other end seated on respective posts 32A, 32B at the bottom of each track 31 A, 31 B. As will be appreciated, with this configuration, lateral force applied on the top of the shoulders will compress springs and allow the shutter to descend down the tracks at an angle which serves to provide both horizontal and lateral displacement of the shutter as will be described in more detail below.

[0045] The TR sub-assembly 10 described above is sized and configured to sit beneath the hot and neutral plug openings in the face plate of a TR receptacle. Once assembled and included as part of a TR receptacle, the shutter 40 of the TR subassembly is spring biased via lateral springs 80A, 80B against the underside of the TR receptacle faceplate. As such, the hot blade blocking surface 42 and the neutral blade blocking surface 43 of the top surface 41 of the shutter 40 block the hot and neutralopenings of the faceplate. The spring bias and planar nature of the surfaces ensures that the blade openings (and electrical contacts underneath) are individually inaccessible to a child attempting to insert an object in one of the respective hot or neutral openings. The blocking of the blade openings is maintained by the bias of the shutter 40, unless and until, there is a simultaneous insertion of both the hot 101 and neutral blades 102 of an electrical plug 100 into the TR receptacle.

[0046] Specifically, once biased in the closed position, the insertion of a single blade or object into just the hot blade opening of a TR receptacle will result in direct vertical force being directed downward onto the shutter 40. The angle of the rails 30A, 30B and the shoulders of the shutter prevent the shutter from moving along the track 31 A, 31 B with just vertical forces the shutter will tip in the direction of the force and minimal clearance of the shoulders and track serve as a mechanical stop from traveling and compressing the springs. Accordingly, there will be no access as the shutter’s hot blade blocking surface 42 remains directly under the hot blade opening.

[0047] Likewise, the insertion of a single blade or object into just the neutral blade opening of the TR receptacle will be blocked by the neutral blade blocking surface 43 of the shutter 40. The application of vertical force will not result in movement of the shutter as the rear flange and block prevent pivotable movement while the shoulder and track placement also serve as a mechanical stop to prevent any lateral movement thus keeping the neutral opening (and neutral contact) inaccessible.

[0048] However, upon simultaneous insertion of both the hot 101 and neutral blades 102 of an electrical plug 100 into the hot and neutral opening of the TR receptacle faceplate will result in access to the electrical contacts and the ability for the electrical plug to plug into the receptacle. As shown in connection with a 15-Amp device as in in FIGs. 9-1 1 , with simultaneous insertion of the plug blades, the downward force on the hot blade blocking surface and the neutral blade blocking surface creates dynamic vertical and lateral movement of the shutter. As will be appreciated, as both surfaces are simultaneous receiving vertical force, the shoulders will align in the tracks of the housing on the hot end and the medial spring will receive force from the cam being forced to move do to translation of the downward movement to the lateral direction by camming action of the block. The continued downward and lateral movement of the shutter will continue asthe force is continued to be simultaneously applied by the plug blades 101 , 102 to the hot and neutral blocking surfaces until the plug is fully inserted. Upon retraction of the plug blades, the bias of the spring returns the shutter member to its original position blocking the plug openings.

[0049] In a 20-amp TR device, as shown in FIGS. 12-14, the lateral spring members begin to compress under force as the shoulders being to travel along the tracks as with the 15-amp device. In addition, as the shutter member descends and the downward force in the neutral blade area provides force against the cam surface of the block, the medial spring is compressed. Compression of the medial spring and movement of the block provide clearance for access to the T-shaped opening in the bottom of the housing. At the same time, continued compression of the lateral springs causes the shutter to travel downwardly at an angle towards toward the hot end of the receptacle. The diagonal movement moves the shutter into a position exposing the hot blade opening of the shutter which allows the hot blade to enter the housing via the hot blade opening behind the hot blade blocking surface and to continue travel downwardly until it reaches the hot electrical contact. Likewise, in conjunction with the compression of medial spring, the lateral movement of the shutter removes the neutral blade blocking surface from blocking the neutral blade from descending through the housing.

[0050] Upon full insertion of the plug, the shutter has been vertically and laterally displaced by overcoming the bias of the springs. Upon retraction of the plug, the springs operate to return the TR sub-assembly to the original position blocking access to the hot and neutral blade opening of the TR receptacle. Specifically, as the plug is removed, the lateral springs expand to bias against the posts of shoulders to push the shutter upwards while the medial spring pushes the cam block back to its original position and the neutral blade allows the shutter to travel laterally back to its original position.

[0051] The above examples and similar examples use few parts and are thus easy and cost effective to build. Fewer parts also increase the useful life of the products as there are fewer points of failure. Fewer parts and simple mechanical interaction also increase the lifespan of the products. All of these benefits help to encourage and increase the use, availability, and reliability of these important safety products.

[0052] The above-described example utilized a pair of lateral spring members. A pair of spring members disposed on opposite sides provides the advantage of redundancy and prevents binding non-uniform movement of the shutter. However, one of ordinary skill in the art will readily appreciate that a single lateral spring, or a single centrally disposed angled spring could easily be used in various examples according to the present disclosure. Similarly, while a helical spring member is used for the medial spring (or lateral springs), other types of biasing springs and components could equally be used according to various examples of the present disclosure.

[0053] One of ordinary skill will appreciate that the exact dimensions and materials are not critical to the disclosure and all suitable variations should be deemed to be within the scope of the disclosure if deemed suitable for carrying out the objects of the disclosure.

[0054] One of ordinary skill in the art will also readily appreciate that it is well within the ability of the ordinarily skilled artisan to modify one or more of the constituent parts for carrying out the various examples of the disclosure. Once armed with the present specification, routine experimentation is all that is needed to determine adjustments and modifications that will carry out the present disclosure.

[0055] The above examples are for illustrative purposes and are not intended to limit the scope of the disclosure or the adaptation of the features described herein. Those skilled in the art will also appreciate that various adaptations and modifications of the above-described preferred examples can be configured without departing from the scope and spirit of the disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the disclosure may be practiced other than as specifically described.

Claims

CLAIMSWhat is claimed is:1 . A tamper-resistant receptacle sub-assembly comprising: a body having a bottom surface, a pair of opposing side walls, and an open top; a pair of inclined guide rails on each of said opposing side walls defining a respective track; a spring member disposed in each respective track; a medial spring member; a cam body in contact with said medial spring member; a shutter member disposed in said open top; said shutter member being configured to travel in said tracks to move said shutter member.

2. The tamper-resistant receptacle sub-assembly of claim 1 , wherein said shutter member includes a pair of lateral shoulder members in contact and configured for traveling in said tracks.

3. The tamper-resistant receptacle sub-assembly of claim 2, wherein each lateral shoulder of the pair of lateral shoulders includes a spring post for receiving a respective one of the spring members.

4. The tamper-resistant receptacle sub-assembly of any one of claims 1 to 3, wherein said shutter member includes a blade opening, whereby lateral movement of said shutter member moves said blade opening into a position for allowing a blade to be inserted into said sub-assembly.

5. The tamper-resistant receptacle sub-assembly of any one of claims 1 to 4, wherein said shutter member includes a hot blade blocking surface, a neutral blade blocking surface, and a hot blade opening; and wherein cam body includes spring mount and a cam surface; whereby vertical force on both of said hot blade blocking surface and said neutral blade blocking surface causes said shutter member to move vertically and laterally to allow a hot blade and a neutral blade of an electrical plug to enter said sub-assembly.

6. The tamper-resistant receptacle sub-assembly of claim 5, wherein said cam surface is curved and a cam block moves laterally by camming force applied vertically to said cam surface to overcome a bias of medial spring member.

7. The tamper-resistant receptacle sub-assembly of claim 5 or claim 6, wherein simultaneous insertion of a hot plug blade and a neutral plug blade causes simultaneous compression of medial spring and lateral spring members to cause vertical and lateral movement of said shutter member.

8. The tamper-resistant receptacle sub-assembly of any one of claims 5 to 7, wherein the medial spring is coupled to a spring post on a first side wall of the pair of opposing side walls, wherein a solid portion extends from a second side wall of the pair of opposing side walls, and wherein the cam body proximate to the cam surface is configured to contact the solid portion in a neutral position of the medial spring and move away from the solid portion when the medial spring is compressed.

9. The tamper-resistant receptacle sub-assembly of any one of claims 1 to 8, wherein the spring members are parallel to one another, and each spring member is oriented at a 45 degree angle with respect to the bottom surface, and wherein the medial spring extends parallel to the bottom surface and perpendicular to the pair of opposing side walls.

10. The tamper-resistant receptacle sub-assembly of any one of claims 1 to 9, wherein the bottom surface includes a first opening and a second opening spaced apart from the first opening, and wherein the second opening has a different shape than the first opening.1 1 . The tamper-resistant receptacle sub-assembly of claim 10, wherein the first receptacle has a rectangular shape, and wherein the second receptacle has a T-shape.

12. A tamper-resistant receptacle sub-assembly comprising: a body having a bottom surface, a pair of opposing side walls, and an open top; a pair of inclined guide rails on each of said opposing side walls defining a respective track; a spring member disposed in each respective track; a shutter member disposed in said open top;said shutter member being configured to travel in said tracks to move said shutter member.

13. The tamper-resistant receptacle sub-assembly of claim 12, wherein said shutter member includes a pair of lateral shoulder members in contact and configured for traveling in said tracks.

14. The tamper-resistant receptacle sub-assembly of claim 13, wherein each lateral shoulder of the pair of lateral shoulders includes a spring post for receiving a respective one of the spring members15. The tamper-resistant receptacle sub-assembly of any one of claims 12 to 14, wherein said shutter member includes a blade opening, whereby lateral movement of said shutter member moves said blade opening into a position for allowing a blade to be inserted into said sub-assembly.

16. The tamper-resistant receptacle sub-assembly of any one of claims 12 to 15, wherein said shutter member includes a hot blade blocking surface, a neutral blade blocking surface, and a hot blade opening; whereby vertical force on both of said hot blade blocking surface and said neutral blade blocking surface causes said shutter member to move vertically and laterally in said tracks to allow a hot blade and a neutral blade of an electrical plug to enter said sub-assembly.

17. The tamper-resistant receptacle sub-assembly of any one of claims 12 to 16, wherein the spring members are parallel to one another, and each spring member is oriented at a 45 degree angle with respect to the bottom surface.

18. The tamper-resistant receptacle sub-assembly of any one of claims 12 to 17, wherein the bottom surface includes a first opening and a second opening spaced apart from the first opening, and wherein the second opening has a different shape than the first opening.

19. The tamper-resistant receptacle sub-assembly of claim 18, wherein the first receptacle has a rectangular shape, and wherein the second receptacle has a T-shape.

20. A tamper-resistant receptacle sub-assembly comprising: a body having a bottom surface, a first side wall perpendicular to the bottom surface, a second side wall parallel to the first side wall, and an open top; first inclined guide rails extending along the first side wall defining a first track;a medial spring member coupled between the first side wall and a cam body; a shutter member disposed in said open top; a spring member disposed in the first track and connected to the shutter member; said shutter member being configured to travel in the first track to move said shutter member toward the bottom surface against a bias of the spring member.21 . The tamper-resistant receptacle sub-assembly of claim 20, wherein said shutter member includes a lateral shoulder member in contact and configured for traveling in said first track.

22. The tamper-resistant receptacle sub-assembly of claim 21 , wherein the lateral shoulder includes a spring post for receiving a respective the spring member.

23. The tamper-resistant receptacle sub-assembly of any one of claims 20 to 22, wherein said shutter member includes a blade opening, whereby lateral movement of said shutter member moves said blade opening into a position for allowing a blade to be inserted into said sub-assembly.

24. The tamper-resistant receptacle sub-assembly of any one of claims 20 to 23, wherein said shutter member includes a hot blade blocking surface, a neutral blade blocking surface, and a hot blade opening; and wherein cam body includes spring mount and a cam surface; whereby vertical force on both of said hot blade blocking surface and said neutral blade blocking surface causes said shutter member to move vertically and laterally to allow a hot blade and a neutral blade of an electrical plug to enter said sub-assembly.

25. The tamper-resistant receptacle sub-assembly of any one of claims 20 to 24, wherein the bottom surface includes a first opening and a second opening spaced apart from the first opening, and wherein the second opening has a different shape than the first opening.

26. The tamper-resistant receptacle sub-assembly of claim 25, wherein the first receptacle has a rectangular shape, and wherein the second receptacle has a T-shape.

27. The tamper-resistant receptacle sub-assembly of claim 25 or claim 26, wherein the cam body selectively obstructs access to the second opening.

28. A tamper-resistant receptacle sub-assembly comprising:a body having a bottom surface, a first side wall perpendicular to the bottom surface, a second side wall parallel to the first side wall, and an open top; first inclined guide rails extending along the first side wall defining a first track; a medial spring member coupled between the second side wall and a cam body; a shutter member disposed in said open top; a spring member disposed in the first track and connected to the shutter member; said shutter member being configured to travel in the first track to move said shutter member toward the bottom surface against a bias of the spring member.

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