Abstract:
An electrical continuity tester has a handheld housing having batteries, switch, test bulb, a probe and a power cord having a grounded plug on the end of the power cord. The handheld tester is used to first check that a common grounded outlet is wired properly by closing the switch and observing the test bulb. The test bulb should come on if the grounded outlet is wired properly. After the outlet has been verified, the probe can be used to touch any metal or conductive parts of any electrical device or appliance to verify that the metal part is properly grounded or wired to the hot side of the circuit. The tester&#39;s the cord and plug provides one connection and the probe provides the other connection.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a device for testing electrical continuity in electrical circuitry, and more specifically to a device for detecting proper grounding for all switches, receptacles, light fixtures, and appliances throughout the house or building before electrical power is applied to the house or building.  
           [0003]    2. Description of the Related Art  
           [0004]    Devices that test electrical continuity in electrical circuitry and that also check for proper grounding of electrical devices throughout the house or building often require that the electrical power be applied and turned on to the building or circuit under test. These devices, which sometimes include outlet plug adapters, require the circuit under test to be hot. Therefore, these devices cannot be used to verify the correct wiring of newly constructed houses or buildings by building inspectors or electricians before utility power is applied and turned on. Also, these devices cannot be used to test or diagnose faults due to wear and tear in old circuits when the fault is a short that prevents the circuit breaker or fuse from applying power to the circuit.  
           [0005]    Other known devices can test electrical continuity in circuits that are not connected to a power source, but do not have a convenient means to plug into outlets while probing other circuit devices for proper wiring. Without such a convenient means, the inspector or electrician must use extra long jumper wires having alligator clips on each end, or a string of connected jumper wires having alligator clip ends in order to connect at least one probe of the continuity checker to a more remote device in the circuit. Also, alligator clip ends do not lend themselves to easy attachment to female contacts in outlets, or to grounded metal parts that do not have a shape which can be grabbed by the alligator clips.  
           [0006]    U.S. Pat. No. 3,711,768, issued to Frazin on Jan. 16, 1973, and U.S. Pat. No. 3,775,677, issued to Garrett et al. on Nov. 27, 1973, each show a combined flashlight and continuity checker in one device. Although these devices have light bulb and battery elements and the alligator clips of a continuity checker, it does not have the convenience of a probe and a power cord with grounded plug.  
           [0007]    U.S. Pat. No. 3,753,090, issued to Tomek on Aug. 14, 1973, and U.S. Pat. No. 5,406,207, issued to Shershen on Apr. 11, 1995, and U.S. Pat. No. 6,232,784, issued to Dulasky on May 15, 2001, also show a combined flashlight and continuity checker in one device. Although these devices have light bulb and battery elements and the short stubby probes of a continuity checker, they do not have the convenience of a probe and power cord with grounded plug.  
           [0008]    U.S. Pat. No. 4,041,380, issued to Epstein on Aug. 9, 1977, shows a combined flashlight and continuity checker in one device. Although this device has light bulb and battery elements with the long probe and alligator clip end of a continuity checker, it does not have the convenience of a probe and power cord with grounded plug, as in the present invention.  
           [0009]    U.S. Pat. No. 4,857,826, issued to Graham on Aug. 15, 1989, is continuity circuit checker which requires a circuit to be hot in order to carry out the testing and uses neon light bulbs to carry out the tests.  
           [0010]    U.S. Pat. No. 6,054,849, issued to Collier et al. on Apr. 25, 2000, is continuity circuit checker for checking the continuity of electrical cables and cords having plugs on the ends. Thus the Collier device has many outlets to facilitate the testing.  
           [0011]    It would be desirable to provide a device that can test electrical continuity in building or house circuits when power is not applied to the wiring, and which provides quick, convenient and secure means to make the necessary connections and contacts between the electrical devices in the circuit. It would also be desirable to provide a device that can test electrical continuity in a building circuit that is not restricted by the distance between two testing points.  
           [0012]    None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, an electrical continuity tester solving the aforementioned problems is desired.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention is an electrical continuity tester that solves the above problems by providing a handheld housing having batteries, switch, test bulb, a probe and a power cord having a three-prong plug, including a ground prong, on the end of the power cord. The handheld tester is used to first check that an unpowered grounded outlet is wired properly by closing the switch and observing the test bulb. The test bulb should come on if the grounded outlet is wired properly. After the outlet has been verified as wired properly, the probe can be used to touch any metal or conductive parts of any electrical device or appliance to verify that the metal part is properly grounded or properly wired to the hot side of the circuit, when the circuit is unpowered. Usually continuity tests require two connections of a continuity device to be made, but with the present invention the cord and plug provide one connection and the probe provides the other connection. Since the cord and plug are common and the outlets they plug into are available throughout the building or house, the range and reach of the handheld tester probe to the test points on the electrical devices are limitless.  
           [0014]    Accordingly, it is a principal object of the invention to provide an electrical continuity tester that has no restrictions on its ability to test continuity between any two points in a circuit in a building.  
           [0015]    It is another object of the invention to provide an electrical continuity tester that may be used with one hand once plugged into a verified common outlet.  
           [0016]    It is a further object of the invention to provide an electrical continuity tester that can check continuity or proper wiring of a variety of electrical devices in an unpowered building.  
           [0017]    Still another object of the invention is to provide an electrical continuity tester that can check continuity or proper wiring or short in an unpowered building or circuit.  
           [0018]    It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.  
           [0019]    These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a schematic diagram of an electrical continuity tester, showing the manner of connecting the device to various circuits and appliances according to the present invention.  
         [0021]    [0021]FIG. 2 is a perspective view of the electrical continuity tester with cord and grounded plug according to the present invention.  
         [0022]    [0022]FIG. 3 is a detailed schematic of the electrical continuity tester during initial use and setup according to the present invention, the tester housing shown in phantom to show internal components.  
         [0023]    [0023]FIG. 4 is a detailed schematic of the electrical continuity tester testing a four-prong 220-volt electrical appliance outlet according to the present invention.  
         [0024]    [0024]FIG. 5 is a detailed schematic of the electrical continuity tester testing a lamp socket according to the present invention.  
         [0025]    [0025]FIG. 6 is a detailed schematic of the electrical continuity tester testing a ceiling lamp, range-oven, washer-dryer, or other similar appliance, according to the present invention.  
         [0026]    [0026]FIG. 7 is a detailed schematic of the electrical continuity tester testing a multiple switch assembly according to the present invention. 
     
    
       [0027]    Similar reference characters denote corresponding features consistently throughout the attached drawings.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    Referring to FIGS. 1 and 2, the continuity checker  10  has a probe  18 , which is used to provide temporary connection under test to the electrical fixtures and appliances  36 ,  38 ,  40 ,  41 ,  42  and  43 . The connecting line  8  illustrates the metal points on the electrical appliances  36 ,  38 ,  40 ,  41 ,  42  and  43  that the tip of the probe  18  touches while being tested by the electrician who is using the tester  10 . Lines  4  and  6  illustrate some of the ground lines that connect metal parts on the electric range-oven  41 , electric washer-dryer  40 , and switch plate  38  to the ground-neutral bus bar  32  in the power main panel box  28 .  
         [0029]    Main cut off switch or circuit breaker  29  controls electric power and will typically be set in the off position during testing using the tester  10 . Circuit breakers  30  control power to individual circuits throughout the house including circuits for the outlet  34 , switches  38 , light fixtures  42 , light bulb socket  43 , 220 volt, four-prong, female contact, grounded dryer outlet  36 , range-oven  41  and dryer  40 . Line  50  is an example of one of the hot side wirings, which is connected from the switches  38  to the circuit breaker  30  in the main power box  28 . Outlet  34  is the typical 120-volt three-prong female contact grounded outlet used throughout U.S. houses and buildings. Switches  38  control power for further outlets  34  and fixed light fixtures  42 .  
         [0030]    In FIGS. 1 and 2, the continuity checker  10  uses a 15 foot recoilable cord  19  with three-prong grounded plug  20  on its end that is plugged into a three-prong female contact grounded outlet  34 . The three-prong plug  20  has a ground prong  22 , a neutral prong  24  and a hot prong  26  which mate with the female contacts in outlet  34  in only one way. The body of the tester  10  holds a pair of batteries inside a holder, a light bulb or L.E.D.  14 , a lens  16 , a switch  12  and a probe  18 . The switch  12  provides control over the test modes. The lens  16  is a colored or transparent piece, which protects the light source  14 , while allowing the light radiating from light source  14  to be visible. FIGS. 1 and 3 show how a properly wired three prong female contact 120 volt grounded outlet in any U.S. building or house is wired back to elements in the main electrical panel  28  according to the National Electrical Code.  
         [0031]    [0031]FIG. 3 shows a schematic to illustrate the initial test mode that will test continuity and proper wiring of the outlet  34  while no power is applied to the building through the main circuit breaker  29 . The batteries  11  are connected in series between one end of the light  14  and the ground prong  22  which, when mated to the ground female contact in outlet  34 , allows for a circuit path back to the ground bus bar  32 . The other end of the light  14  is connected to the switch  12  and the probe  18 . The other side of the switch  12  is connected to the neutral prong  24 , which is plugged into the neutral female contact in outlet  34 , and which connects back to the ground or neutral bus bar  32 . Thus, current flows from the battery  11 , through the light  14 , through the switch  12 , through the neutral female contact of the outlet  34  through the neutral-ground bus bar  32 , through the ground of the outlet  34  and back to the battery  11 .  
         [0032]    Once the switch  12  is turned on, the plug  20  is plugged into the outlet  34  and the probe  18  is not touching any object or device, the light  14  should come on if the outlet  34  has been wired correctly. When the switch  12  is closed (turned on) the circuit path between the light  14  and the batteries  11  is complete as shown by the arrows shown along the conductor lines. If the light  14  does not come on then the outlet  34  is not properly grounded and there is a break in the circuit. An outlet that tests bad cannot be used by the tester  10  for further tests of other devices.  
         [0033]    Once an outlet  34  has been tested as wired correctly by the above procedure the tester  10  can be used to test further electrical devices. Assuming the outlet  34  is within a range of the length of the power cord  19  to the next electrical device to be tested and the switch  12  is turned off (open), then the user touches the probe  18  to metallic or conductive parts or areas of the electrical devices  36 ,  38 ,  40 ,  41 ,  42 ,  43  that should be grounded, as indicated by the light  14  turning on. When the switch  12  is turned off, and the user touches the probe  18  to metallic or conductive parts or areas of the electrical devices  36 ,  38 ,  40 ,  41 ,  42 ,  43  that should be hot, then the light  14  should remain off.  
         [0034]    In the case of switches  38  in shown FIG. 1, the probe  18  touches the metal screws or metal plate of the switches  38  and the light  14  should come on indicating that the body of the switches  38  are properly wired for ground. FIG. 7 shows the circuit path for current flow from the batteries  11  through the light  14 , through the probe  18 , through the metal parts of the body of the switches  38  to the ground-neutral bus bar  32  to the ground of the outlet  34  through the plug  20  and cord  19  back to the batteries  11 . Current through the open switch  12  on the tester  10  does not flow, so that the light  14  only turns on if there is continuity between the metal screws of the switch  38  face plate and the ground bus bar  32 .  
         [0035]    In the case of light fixtures  42  shown in FIG. 1, the probe  18  touches the grounded metal knob of the fixed light fixture  42  and the light  14  should come on indicating that the light fixture  42  is properly grounded. FIG. 6 shows the circuit path  4  for current flow from the batteries  11  through the light  14 , through the probe  18 , through the metal knob of the light fixture  42  to the ground-neutral bus bar  32  to the ground of the outlet  34  through the plug  20  and cord  19  back to the batteries  11 .  
         [0036]    In the case of electric range-oven  41  or washer-dryer  40  shown in FIG. 1 which have large portions or areas of metal parts that are supposed to be grounded, the probe  18  touches any of the areas of the metal parts of the range-oven  41  or washer-dryer  40  and the light  14  should come on indicating that these devices are properly wired for ground. FIG. 6 shows the circuit path  4  for current flow from the batteries  11  through the light  14 , through the probe  18 , through the metal parts of the range-oven  41  or washer-dryer  40  to the ground-neutral bus bar  32  to the ground of the outlet  34  through the plug  20  and cord  19  back to the batteries  11 .  
         [0037]    In the case of a light fixture socket  43  shown in FIG. 1, the probe  18  touches the grounded metal screws of the light socket  43  and the light  14  should come on indicating that the light socket  43  is properly wired for ground. FIG. 5 shows the circuit path  4  for current flow from the batteries  11  through the light  14 , through the probe  18 , through the metal screws holding the light socket  43  through the ground-neutral bus bar  32  to the ground of the outlet  34  through the plug  20  and cord  19  back to the batteries  11 . Then, the probe  18  is held to touch the brass colored rectangular hot contact in the light socket  43  as shown in FIG. 1 and the light  14  should stay off indicating the correct wiring of the hot side wiring of the light socket  43 . FIG. 5 shows the circuit path for current flow from the batteries  11  through the light  14 , through the probe  18  (touching the hot line) though the hot line  50  to stop and go no further than the circuit breaker  30 .  
         [0038]    In the case of a grounded 220 volt dryer outlet  36  as shown in FIG. 1, the probe  18  touches the grounded female contact or screw of the grounded 220 volt dryer outlet  36  and the light  14  should come on indicating it is properly wired for ground. FIG. 4 shows the circuit path  4  for current flow from the batteries  11  through the light  14 , through the probe  18  (dotted line  18 ), through the grounded female contact or screw of the ground dryer plug  36  through the ground-neutral bus bar  32  to the ground of the outlet  34  through the plug  20  and cord  19  back to the batteries  11 .  
         [0039]    Then, the probe  18  is held to touch the neutral female contact or screw in the grounded dryer outlet  36  as shown in FIG. 1 and the light  14  should be on indicating the correct wiring of the neutral line  7  in the dryer plug  36 . FIG. 4 shows the circuit path  7  for current flow from the batteries  11  through the light  14 , through the probe  18  (touching the neutral line) though the ground-neutral bus bar  32  to the ground of the outlet  34  through the plug  20  and cord  19  back to the batteries  11 . The two hot side wirings  50  can also be tested in the same manner as mentioned above with respect to FIG. 5 by touching the probe  18  to the two hot side female contacts in the outlet  36 .  
         [0040]    As one of ordinary skill in the art, including electricians, building inspectors and electrical engineers, can see, the advantage to the present invention is the handheld device  10  and its one long power cord  19  and plug  20  to test an infinite variety of electrical devices in the building before power is applied, or when power is disconnected, or when power is not turned on. Thus, the user of the tester  10  does not have to rely on jumper cables or wires that are strung together and have alligator clip ends that are often inconvenient or which easily come loose. The three-prong plug  20  and cord  19  of the tester  10  can even be extended by conventional extension cords. Also, adaptors for alligator clips to hold on to the female contacts of other kinds outlets do not have to made because of the long probe  18  on tester  10 .  
         [0041]    In the case of outlets or switches, cover plates never have to be removed to check for proper grounding, since the probe tip  18  can touch the smallest area of metal part even if it is the screw in a plastic cover plate. Such operations with the probe  18  and long power cord  19  are one-handed avoiding two-handed situations when the alligator clips are not securely attached or have long pulls on their wire. The one-handed operation and probe  18  free the inspector or electrician to test all the metal areas on large electrical appliances  40 ,  41  such as stoves, ovens, washers, dryers, furnaces, main circuit panel boxes, etc. even when the metal areas are separated by plastic areas.  
         [0042]    The tests with the probe  18  and tester  10  allow for further tests to show correct wiring of the hot wire of the electrical devices while utility power is not applied. Thus, the device of the present invention can be used with all the conveniences as mentioned above during the testing and locating of a short in the wiring or devices connected in the circuit when the power is removed and cannot be applied because of the short.  
         [0043]    [0043]FIGS. 1 and 2 show how a properly wired three prong female contact 120 volt grounded outlet in any building is wired back to elements in the main electrical panel  28  according to the NFPA (National Fire Protection Association)  70 , NEC (National Electrical Code). The tester of the present invention also provides pass-fail testing of the proper grounding of electrical devices according to the NEC (National Electrical Code). The NEC is a set scientifically and consensus based codes and standards having a long list of organizations on the code making panel.  
         [0044]    It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.