Patent Application
20140340903
1. Field of the Invention
The present invention generally concerns a portable cord, also known as portable cordage, for temporary deployment that attaches, permissibly among other things, temporary work lamps, or lights, along its length, thus nominally a “temporary work light string”.
The present invention particularly concerns (1) the positioning of lamps, or lights, along the length of a temporary work light string, and (2) the management of electrical circuits within a temporary work light string and within any devices, including lamps or lights, that are electrically connected to such temporary work light string.
2. Background of the Invention
2.1 Portable Cords
The present invention will be seen to involve a portable temporary power cord, or cable, that can physically attach and electrically connect along its length, among other things, work lamps.
According to the entry “Portable Cord” appearing circa 2012 in Wikipedia, the free encyclopedia of the Internet, “[a] portable cord, which is also known as portable cordage or flexible cord, is a cable with multiple conductors used for functions requiring flexibility. The cord can be employed for power in a range of applications, such as operating motors in small and large tools, equipment, power extensions, home appliances and machinery.
“Portable cords may be used in commercial, industrial and residential applications. They work well on job sites where resistance to oil, chemicals and abrasion is vital and also perform well in extreme environments—both the heat and the cold, outside or inside. Additionally, some portable cords can be water-resistant or water submersible. Because of their characteristics, portable cords are commonly used in a range of facilities, such as construction sites, mills, mines, sports complexes, or even marinas.
“Although the construction of a portable cord varies depending on the type, a standard cord has at least two stranded copper conductors. The copper stranding, insulation and jacket directly influence the physical properties of the cord.”
The most preferred cord material of the present invention will be seen to be Type SEOW. Continuing in the Wikipedi entry:
“A variety of portable cords, differing in styles, lengths and thicknesses, exist in the marketplace. Common types include Type SJT, SVT, SEOW, SJ, SJOW, SO and SOW. Each has specific applications associated with it. A portable cord is usually made of thermoset, thermoplastic elastomer, or thermoplastic. Thermoset cords have heavy-duty-grade rubber jackets and are extremely sturdy. Thermoplastic elastomer cords have medium-duty-grade thermoplastic elastomer jackets and perform well in cold conditions. Thermoplastic cords have a light-duty plastic compound jacket and thus work for light-duty use.”
The preferred Type SEOE is a Thermoplastic elastomer (TPE). As explained in the 2000 article “Don't Let Your Portable Cord Tie You Up” appearing on the World Wide Web at the Electrical Construction and Maintenance website, “[t]hese cords have medium-duty-grade thermoplastic elastomer jackets. UL designations for these cords are SEOW-A and SJEOW-A. CSA designations for these cords are STW and SJTW-A.
“TPE compounds are lightweight in comparison to the rubber materials . . . [found] in thermoset cords. Approved for indoor and outdoor use, TPE is a better choice than plastic materials for some commercial outdoor construction in northern regions. It performs well in cold temperatures (−50 degrees Celsius/−58 degrees Fahrenheit). You'll see this type of material in some standard extension cords.
“TPE cords resist water, oil, cuts, chemicals, and acid. They also handle exposure to weather, sunlight, and ozone. You can get these in a flame-retardant version. However, the CSA designation for this type of cord (STW) carries no recognition for oil resistance. The agency marks this cable as a “T” type, thermoplastic: a plastic compound.
“Although manufactured like a thermoset product and able to perform in temperatures up to 105 degrees Celsius/221 degrees Fahrenheit, TPE may not stand up in environments where extreme heat and hot oil are factors. When exposed to such circumstances, the cord may disfigure or melt, making it useless.’
2.2 Limitations of Previous Portable Temporary Power Cords
Previous portable temporary power cords attache lamps in fixed positions along the length of the cord, normally at even spacing after an initial interval from the plug that is typically longer than is the space between lamps. Such a construction is, almost by definition, likely unsuitable in detail for the illumination of the interior spaces, or rooms, of a building which rooms are typically not linear, and which are accessed through doors and windows at which points lamps may be inappropriate for, among other reasons, shining in the eyes of persons passing or looking through such portals.
More troublesome than sub-optimal lamp locations are the quite frequent occurrences during construction when more light is needed at a specific location. This entail moving the whole work light string, and all or most of the lamps along it. Reasons for moving the string include so as to prevent the lamps from becoming buried or enclosed or trapped above equipments, avoidance of suspended ceilings and/or of framing and/or of sheet rock, or prevention of capture between walls. The operation of moving an entire light string so as to move and relocate but a single lamp may become labor intensive and may even require the labor of more than one person.
Further, and more seriously, lamps that are located in fixed positions along the length of a temporary power cord most typically cannot be replaced if damaged. The only alternative to discarding the entire work light cord is to cut out a damaged light and splice the cord back together in an improved manner, typically leaving both an undesirable bulge on the cord and dimensional unevenness in the location of lights along the cord. This repair requires materials and time, and is seldom done even by skilled electricians upon their own work light cords.
Finally, existing work light cords are normally connected to but a single electrical circuit, which is normally rated at 20 amperes/This means, as a practical matter, that the largest and longest work light strings are no more than ten 100-watt light bulbs, and 100 feet in length. Moreover, the ability to power additional loads from these work light cords—such as at a receptacle at the end of the cord o by screwing into an Edison socket normally taking an light bulb—is limited. It would be useful if the lengths, current capacities, and/or flexibility (in numbers and in positions of the attachment(s) of electrical loads to a work light cord could be improved.
The present invention contemplates an improvement to a temporary work light string having (1) a flexible electrical cord, or cable, physically mounting and electrically connecting (2) lamps, or lights, along its length wherein the powered lamps are variably positionable, and re-positionable, and readily-replaceable along the length of the cord or cable.
The present invention further contemplates that a temporary work light string should be based on an electrical cord, or cable, containing a plurality of separate electrical circuits, normally two such circuits. Each circuit serves to power those electrical devices, particularly including lamps or lights, to which it is electrically connected.
1. A Work Light String with Variably-Positionable Lamps or Lights
Accordingly, in one of its aspects the present invention is embodied in a work light string having variably-positionable lamps or lights.
The string includes (1) a flexible electrical cord/cable, pluggable to electric power at a one end thereof, physically mounting and electrically connecting (2) a plurality of lamps/lights along its length. The lamps/lights are variably positionable, and re-positionable, and replaceable along the length of the cord/cable at a time after the manufacture thereof, and without severing and splicing the cord/cable.
The cord/cable so performing has both (1) external insulation and (2) internal conductors where the (1) external insulation is penetrable by a pressured metal prong or blade to make electrical contact with an (2) internal conductor.
The (1) penetrable external insulation of the cord cable is preferably self-healing upon the withdrawal of any metal prong or blade so as to squeeze shut any penetrating hole made by the metal prong or blade. the cord/cable having self-healing penetrable external insulation is most preferably Type SEOW.
The variably positionable, re-positionable and replaceable lamps light along the length of the cord/cable preferably include (1) a first-part assembly suitable to hold an electric lamp to which electrical connection is made by a one, first, end of at least two metal conductors within the assembly, screwed to (2) a second-part assembly. The first- and the second-part assemblies defining between them a channel into which the cord/cable is laid. The at least two metal conductors of the first-part assembly terminate at their second ends in at metal prongs/blades that are within the channel and suitably positioned so that when the first- and the second-part assemblies are screwed together then these at least two metal prongs/blades will under compression force penetrate the external insulation of the cord-cable that is positioned within the channel, and will make electrical connection between at least a power, and a ground, electrical circuit of this cord/cable and the lamp.
Since the physical and the electrical connection of the cord/cable to the lamp did not depend upon any properties of the cord-cable, nor of the assemblies, that were unique to the point of connection, then the assemblies, and the held lamp, are variably positionable anywhere along the length of the cord/cable.
The first-part assembly can preferably be unscrewed from the second-part assembly so as to free the cord/cable held between them, and so as to break and electrical connection of the electrical circuits of the cord/cable to the lamp, without damage to either the cord/cable nor the assemblies, leaving both assemblies and cord/cable suitable for reuse.
The first-part assembly can optionally hold the electric lamp in an Edison screw socket that nominally holds an incandescent light bulb—although other sockets for other bulbs such as of the compact fluorescent and Light Emitting Diode (“LED”) types are eminently suitable. When the Edison screw socket is used (for a bulb of any type) then the electric lamp is replaceable in the first-part assembly by screwing, and the first- and second-part assemblies are replaceable on the cord/cable also by screwing. Accordingly the entire work light string assembles, and disassembles, by screwing. All this screwing is most preferably accomplished solely under force of the hands and fingers.
The second-part assembly preferably further includes a hanger feature that can be used so as to hang (1) all of the second-part assembly, (2) the first assembly and its held lamp to which the second-part assembly is screwed, and (3) a regional portion of the cord/cable held between the first- and second-part assemblies.
This work light can optionally be configured so that its cord/cable contains three electrical conductors side-by-side: one outside conductor being a hot line of a first electrical circuit, the center conductor being an electrical neutral, and the remaining outside conductor being the hot line of a second electrical circuit separate from the first electrical circuit. The two metal prongs/blades of the first-part assembly of the variably positionable, re-positionable and replaceable lamps can be oriented so as to forcibly penetrate the cord/cable insulation, and to make electrical connection with the first electrical circuit only, or can alternatively be oriented so as to forcibly penetrate the cord/cable insulation, and to make electrical connection with the second electrical circuit only. Accordingly (1) the cord/cable contains two separate electrical circuits; and (2) each positionable, re-positionable and replaceable lamp can be electrically connected to either electrical circuit of the cord/cable.
2. A Work Light String with Plural—Normally Dual—Electrical Circuits
In another of its aspects the present invention is embodied in a work light string having plural—normally dual—electrical circuits.
The work light string includes (1) a cord/cable containing a plurality of electrical circuits; and (2) a plurality of lamps along the length of the cord/cable that are electrically connected to at least two different of the plurality of electrical circuits that are within the cord/cable. By this construction an electrical failure in one of the electrical circuits of the cord/cable will not effect those of the plurality of lamps that are electrically connected to any other one or ones of the electrical circuits.
Further, the plurality of lamps are preferably variably positionable, and re-positionable, along the length of the cord/cable.
The cord/cable preferably contains two electrical circuits. This cord/cable containing two electrical circuits preferably has at least three electrical conductors side-by-side: one outside conductor being a hot line of a first electrical circuit, the center conductor being an electrical neutral, and the remaining outside conductor being the hot line of a second electrical circuit separate from the first electrical circuit.
3. A Work Light String with Both (1) Variably-Positionable Lamps or Lights that (2) can be Electrically Connected Upon Plural—Normally Dual—Electrical Circuits
In yet another of its aspects the present invention is embodied in a work light string having variably-positionable lamps or lights that connect to plural—normally dual—electrical circuits.
The preferred work light string includes (1) a cord/cable containing a plurality of separate electrical circuits; and (2) a plurality of assemblies, each holding one or more electric lamps, that are pluggable anywhere along the length of the cord/cable so as to become electrically connected to one of more of the plurality of electrical circuits that are within the cord/cable, one lamp per electrical circuit. By this construction an electrical failure in one of the electrical circuits of the cord/cable will not effect those of the plurality of lamps that are electrically connected to any other one or ones of the electrical circuits.
In detail of construction, the cord/cable pof the work light string most preferably contains two separate electrical circuits in a row: (1) a hot line conductor wire of a first electrical circuit, (2) a center conductor wire that is an electrical neutral, and (3) a remaining outside conductor wire that is the hot line of a second electrical circuit separate from the first electrical circuit. The plurality of assemblies that hold electric lamps are pluggable to this cord/cable containing two separate electrical circuits carried on three wires. The assemblies are so pluggable so that electrical insulation of the cord/cable is temporarily forcibly penetrated to make (1) electrical connection with the first electrical circuit only, or (2) with the second electrical circuit only, or (3) with both the first and the second electrical circuits where each circuit connects to but one electric lamp held by an assembly.
This work light string has a number of advantages. The assemblies and their held electric lamps can be so plugged anywhere along the length of the cord/cable. The assemblies so plugged may subsequently detached from the cord/cable whereupon the penetrated insulation of the cord/cable is self-healing and closes the penetration holes, leaving each and all of the cord/cable and the assemblies with their contained electric lamps suitable for re-use. Finally, a failure of a one electrical circuit does not cause failure of the electric lights of the work light string that are electrically connected to the other circuit, making that redundancy in lighting is provided by the work light string.
These and other aspects and attributes of the present invention will become increasingly clear upon reference to the following drawings and accompanying specification.
A preferred embodiment of a work light string 1 with variably positionable, re-positionable and replaceable lamps 12 in accordance with the present invention is shown in diagrammatic view in
The work light string 1 consists of a cable 11 proceeding from a first-end standard three-prong male electrical connector, or plug, 112B as to attach along its length a number of lamps—of which exemplary lamps 12A, 12B, . . . 12N are shown—to finally optionally terminate in a standard three prong female electrical connector, or plug, 113B. The cable 11 can electrically connect to, and communicate power ever but a single electrical circuit, but can alternatively connect to, and communicate electrical power over, two separate electrical circuits, as will be illustrated in conjunction with
In detail, when multiple electrical circuits are carried on the cable 11 then (1) a first electrical circuit is carried on internal conductors N (neutral) and L1 (line 1) of cable 11, meanwhile that (2) a second electrical circuit carried on internal conductors N (neutral) and L2 (line 1). An exemplary layout of these internal conductors L1, N and L2 will be shown in
Continuing in
Referring now to
The shaft of the bridal ring 121 may optionally be threaded, and received into a complimentary screw bore (not show) in the aperture where it passes through the top assembly 122. Still further alternatively, the shaft of the bridal ring 121 that is internal to the top assembly 122 may optionally be surrounded by a coil spring (not shown) acting to force the bridal ring 121—which is then not threaded, and which slips freely through the bore at the top of top assembly 122—down into middle assembly 123 and against the cable 11. These possible variations only show that a mechanical engineer can devise many alternatives to force the cable 11 and its conductors into the insulation-piercing metal pieces 1231, 1232 of the bottom assembly 123.
The bridal ring 121 of the top assembly 122 also serves as a convenient hanger of the lamp 12.
By this two-step screwing action the internal conductors 1231, or N; and 1232, or L1; that are within the cable 11 (which is within the groove of the middle assembly 123) are progressively forced by the base of the bridal ring 121 so as to ultimately make physical and electrical contact between these conductors and the insulation-piercing metal pieces 1231, 1232 of the bottom assembly 123. Then, in turn, these insulation-piercing metal pieces 1231, 1232 make electrical contact to the base and side of an Edison screw socket 1233 located at the base of middle assembly 123. An electric light bulb 125 (shown in phantom line for not being a part of the work light string 1 of the present invention) is positioned within a cage 124 (which may be of a snap-open, screwed or other type as is conventional), and screwed into the Edison socket 1233.
To recapitulate, the assembly of a preferred embodiment lamp 12 of a work light string 1 in accordance with the present invention is shown in
Notably, with power safely off, the bridal ring 124 may be loosened in the top assembly 122, and the top assembly 122 may be unscrewed from the bottom assembly 12 so as to loose the cable 11 unharmed and barely marked because its insulating cover is self-sealing. The entire lamp 12 may then be (1) set aside for re-use later, or (2) installed to a new position along the cable 11, as desired.
Diagrammatic views of alternative single- and dual-circuit embodiments of the cord of the preferred work light string in accordance with the present invention are shown in
A dual-circuit three-conductor electrical cable 111b running between a dual-circuit electrical jack 112b and an dual-circuit electrical plug 113b is shown in
Finally, a dual-circuit three-conductor electrical cable 111c now running betweenm, at a one end, the dual-circuit electrical plug 111c and, at the other end, dual-circuit electrical pigtails 111c1, 111c2, 111c3 is shown in
According to these variations, and still others within the skill of a practitioner of the electrical circuit and cord arts, the present invention should be considered in accordance with the following claims, only, and not solely on accordance with those embodiments within which the invention has been taught.
