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Publication numberUS3926494 A
Publication typeGrant
Publication dateDec 16, 1975
Filing dateDec 12, 1973
Priority dateDec 12, 1973
Publication numberUS 3926494 A, US 3926494A, US-A-3926494, US3926494 A, US3926494A
InventorsFelix Maillaro
Original AssigneeNarducci Michael C
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Safety electrical male plug having normally recessed manually extendable contacts
US 3926494 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent 1 [111 3,

Maillaro Dec. 16, 1975 [5 SAFETY ELECTRICAL MALE PLUG 2,490,580 12/1949 Colla, Jr 339/45 R HAVING NORMALLY RECESSED 2,918,647 12/1959 Britt 339/74 R 3,754,205 8/1973 Lenkey 339/42 MANUALLY EXTENDABLE CONTACTS Felix Maillaro, Suffern, NY.

Assignee: Michael C. Narducci, Corona, N.Y.

Filed: Dec. 12, 1973 Appl. No.: 424,167


US. Cl. 339/34; 339/45 R Int. Cl. HOlR 13/44; HOlR 13/62 Field of Search 339/42, 45, 74, 75, 34

References Cited UNITED STATES PATENTS 3/1946 Tiffany 339/42 Primary ExaminerRoy D. Frazier Assistant Examiner-Terrell P. Lewis [57] ABSTRACT An electrical male plug having resiliently urged normally recessed contact prongs that are manually movable to an extended position to enable the insertion of the prongs into a conventional electrical outlet.

5 Claims, 6 Drawing Figures US. Patent Dec. 16, 1975 Sheet 10m 3,926,494

llll2 I l G. Z Z6 48 US. Patent Dec. 16, 1975 Sheet 2 of2 3,926,494



SAFETY ELECTRICAL MALE PLUG HAVING NORMALLY RECESSED MANUALLY EXTENDABLE CONTACTS This invention relates generally to electrical connecting devices and more particularly to a novel safety connecting device that prevents children or other inexperienced persons from accidentally receiving an electrical shock when the novel device is attemped to be inserted in a household electrical receptacle.

It is well known that the conventional male plug attached to lamps or other electrical devices is an attraction to children who mimic their parents and try to insert the plug in an available wall outlet. Often, the children hold the exposed metallic prongs while trying to insert the plug in a live receptacle and are able to connect the projecting terminals of the plug to the female live contacts of the receptacle and obviously receive an electrical shock. The present invention precludes such an accidental shock and thus performs a safety function. When utilized by an adult, the present invention readily plugs into a female socket to connect the device to the source of electrical power.

Accordingly, one of the principal objects of the invention resides in the provision of an electrical male plug having retractable connecting means that are normally positioned in retracted relation to insulate the prongs from accidental human contact when partially connected to a conventional electrical wall outlet.

Another object of the invention is to provide in a device of the class described manually operable means to manually extend the electrical connecting means when it is desired to connect the safety plug to an electrical outlet.

Still another object is to provide resilient retractable means that normally position the connecting means within the insulated housing of the safety plug that can be manually compressed to purposely expose the connecting means when desired to connect the safety plug to an electrical female outlet.

A further object is to provide a plug of the class described that has integral friction means to retain the connecting means in a conventional outlet socket and when manually removed from said socket permit the resilient means to withdraw the connecting means within the insulated plug housing.

Other ancillary objects will be in part hereinafter pointed out and will be in part hereinafter apparent.

In the drawing:

FIG. 1 is a plan elevation of a safety plug incorporating the invention with the connecting prongs retracted within the insulated plug housing.

FIG. 2 is a plan elevation with portions of the housing cut away to illustrate the various components in their respective retracted positions.

FIG. 3 is a plan elevation of the plug with the connecting prongs extended in manually held relation prior to insertion in a female electrical outlet.

FIG. 4 is a plan elevation of the safety plug with portions of the housing cut away to illustrate the respective components with connecting prongs extended to make electrical contact with the live electrical outlet, not shown.

FIG. 5 is a side elevation of the safety plug with the prongs extended, and

FIG. 6 is a bottom view of the safety plug.

Referring to the drawings in detail, 10 generally designates the safety plug having a housing 12 formed of a conventional insulating material, such as polyethelyne or the like. Extending from the housing 12 is a pair of conductors 14 that are connected to the electrical device, not shown. The pair of conductors 14 freely pass through aperture 16 centrally disposed in the upper wall 18 of housing 12. The individual conductors 14a 0 and 14b pass through respective apertures 20 and 22 in slide member 24 to connect with metallic prongs 26 and 28, respectively.

Prongs 26 and 28 are rigidly secured within slide member 24 and are adapted to project through a pair of apertures 30 and 32 disposed in aligned relation with said prongs and located in the lower wall 34 of insulated housing 12. Slide member 24 is provided with a pair of oppositely extending wing grips 36 and 38 respectively that slideably reside in the respective longitudinal recesses 40 and 42 formed in the diametrically opposite sides 44, 46. Wing grips 36 and 38 extend respectively beyond the housing side-walls 44, 46 to facilitate the manual gripping thereof. Slide member 24 is spring urged against upper wall 18 of housing 12 by means of spring 48. In this fully retracted position, prongs 26 and 28 reside within the housing 12. Manual movement of wing grips 36 and 38 downwardly compress spring 48 and projects prongs 26 and 28 through apertures 30, 32 of bottom wall 34.

When held in this extended position, the safety plug may be inserted in a conventional household electrical outlet. When so inserted, the projections 26a and 28a on prongs 26 and 28 frictionally engage the conventional connectors, not shown, in the household electrical outlet, overcoming the tension of spring 48 and thus retain said safety plug in electrical contact with the outlet electrical supply.

A slight manual pull on the plug 10 separates the plug from the outlet and prongs 26 and 28 automatically retract in housing 12 with slide member 24 urged upwardly to abut upper wall 18 of housing 12. In this relationship and from this safe position, children cannot attempt successfully to connect the safety plug to the electrical outlet and thereby avoid possible damaging electrical shocks.

Obviously, conductors 14a and 14b can'be connected to prongs 26 and 28 respectively by soldering or any other conventional means to electrically connect said prongs to the appliance or device connected by plug 10 and conductors 14 as a means of supplying electricity thereto when said plug is inserted in a conventional household electrical outlet.

It will be noted that lower wall 34 of housing 12 is recessed to provide a rim 35. The configuration of rim 35 is such that the recess will receive the projecting portion of a conventional A.C. outlet, not shown, therein. Thus, a sightless person or, in the absence of light, a person can align the safety plug with a conventional A.C. outlet prior to manually extending prongs 26 and 28 for insertion into the A.C. outlet.

While there has been shown and described but a single embodiment of the invention, it will be understood that modification and changes could be made without departing from the scope of the invention as set forth in the following claims:

The invention claimed is:

1. In a safety plug of the class described, in combination,

a. an insulated housing having an opening in one end thereof, and adapted to receive electrical conductors through said opening; a pair of electrical conductors disposed in said opening; a cylindrical wall extending longitudinally from said one end to an opposite end of said housing; an integrally formed wall extending normal to and substantially closing the portion of the housing adjacent to said opposite end, said integrally formed wall being recessed from said opposite end toward said one end; a pair of spaced openings disposed in said integrally formed wall;

b. a pair of spaced metallic prongs disposed in recessed relation within each of said respective openings in said integrally formed wall and connected to said electrical conductors and electrically insulated one from the other;

e. biasing means urging said metallic prongs within the housing to position the ends of the respective prongs within the pair of openings in the integrally formed wall; and

d. means projecting externally of the housing for moving the recessed metallic prongs from their recessed relation within the integrally formed wall of the housing to an extended relation wherein the metallic prongs extend through the integrally formed wall openings and substantially beyond said opposite end of said housing, said means being manually operable.

2. In a safety plug, as set forth in claim 1:

a. said electrical conductors being free to move jointly with said metallic prongs when said prongs are manually moved from their normally recessed position to their extended position.

3. In a safety plug, as set forth in claim 2:

a. said means comprising a pair of oppositely extending finger grips disposed within and extending through a pair of diametrically opposite recesses formed in said housing;

b. said diametrically opposite recesses each being provided with a barrier portion to limit the movement of the respective finger grips when the metallic prongs are manually extended for insertion in a conventional electrical outlet.

4. In a safety plug as set forth in claim 3:

a. said cylindrical wall and said integrally formed wall in said housing forming a recess to define a predetermined rim configuration that is adapted to overlie the conventional electrical outlet and align the metallic prongs when they are extended with the complimentary apertures in the conventional electrical outlet.

5. in a safety plug, as set forth in claim 4:

a. said prongs being provided with means for frictionally engaging conducting elements in the conventional electric outlet to retain said prongs in ex tended relation after said prongs have been inserted in the electrical outlet.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2396901 *Jan 2, 1943Mar 19, 1946Lockheed Aircraft CorpDetachable plug
US2490580 *Feb 18, 1946Dec 6, 1949Colla Jr Nicholas EElectrical connection plug
US2918647 *Dec 14, 1956Dec 22, 1959Britt Thomas OElectrical connectors
US3754205 *May 19, 1971Aug 21, 1973Lenmark Enterprises IncProtected connector plug
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4045106 *Feb 17, 1976Aug 30, 1977Borg John PAutomatic electrical plug release
US4080029 *Mar 10, 1976Mar 21, 1978St Fort RaymondPlug lock
US4105968 *Apr 13, 1977Aug 8, 1978The Raymond Lee Organization, Inc.Electrical tester having retractable prongs and a retractable test rod for indicating presence of a voltage
US4228343 *Dec 29, 1977Oct 14, 1980Schick IncorporatedCollapsible cordless electric hair curling appliance
US4593960 *Mar 27, 1985Jun 10, 1986Amp IncorporatedPower entry connector
US4695925 *Sep 30, 1986Sep 22, 1987Mitsubishi Denki Kabushiki KaishaIC card
US4697070 *Mar 26, 1986Sep 29, 1987Omron Tateisi Electronics Co.Contact lens sterilization device
US5082450 *Nov 5, 1990Jan 21, 1992Warren Sr Charles CSafety plug with ground lock and prong locks
US5085591 *Nov 5, 1990Feb 4, 1992Warren Sr Charles CSafety plug with prong locks
US5393237 *Sep 22, 1993Feb 28, 1995William J. RoyElectric plug locking device
US6139349 *Jul 24, 1998Oct 31, 2000Osram Sylvania Inc.Electrical connector with tactile feedback
US6422883 *Apr 4, 2001Jul 23, 2002Piet Leopold Margriet CoolsTrigger activated ejecting system for electrical plugs
US6913475 *Dec 18, 2003Jul 5, 2005Powertech Industrial Co., Ltd.Electric plug
US7131852 *Aug 30, 2005Nov 7, 2006Sercomm CorporationRetractable plug of power supply
US8366462 *May 10, 2012Feb 5, 2013Powertech Industrial Co., Ltd.Retractable power plug
US9040822 *Mar 12, 2012May 26, 2015Ricardo Nieto LopezSafety device for live electrical wire
US9362669 *Jan 29, 2013Jun 7, 2016Oh Jung KimOutlet unit facilitating plug separation, and multi-outlet device using same
US20050106912 *Dec 18, 2003May 19, 2005Powertech Industrial Co., Ltd.Electric plug
US20120220150 *May 10, 2012Aug 30, 2012Powertech Industrial Co., Ltd.Retractable power plug
US20120228025 *Mar 12, 2012Sep 13, 2012Ricardo Nieto LopezSafety Device for Live Electrical Wire
US20120270435 *Apr 12, 2012Oct 25, 2012Jeramy HaleElectrical safety plug with grip wings for electrical plugs and data cord plugs
US20150140845 *Jan 29, 2013May 21, 2015Oh Jung KimOutlet unit facilitating plug separation, and multi-outlet device using same
EP2590269A1 *Oct 29, 2012May 8, 2013Integration Technique et Cablage (ITEC)Equipped electric conductor
U.S. Classification439/131, 439/159
International ClassificationH01R13/44, H01R13/447
Cooperative ClassificationH01R13/4538
European ClassificationH01R13/453H