Abstract:
An electrical circuit tracing apparatus wherein uniquely identifiable electrical signals are injected into deenergized electrical circuits at a circuit breaker panel. Once the apparatus is electrically connected to multiple deenergized branch circuits, a user may connect a circuit analysis box to successive electrical outlets. The circuit analysis box contains a readout that indicates the circuit number (i.e., 1-n, where n is the number of branch circuits simultaneously testable by the apparatus to which the particular electrical outlet is connected). If a particular electrical outlet is accidentally connected to more than one branch circuit, all of the circuits to which the analyzer box is connected are identified.

Description:
FIELD OF THE INVENTION 
     The invention pertains to electrical circuit testers and, more particularly, to an apparatus for determining which portion or branch circuit of an electrical power distribution network feeds a particular remotely located electrical outlet. 
     BACKGROUND OF THE INVENTION 
     Electricians, maintenance personnel, homeowners, and other interested persons often need to identify to which circuit breaker a particular electrical outlet is connected. This knowledge is necessary so that a particular branch circuit may be deenergized for maintenance, to deal with an emergency such as flooding of an area, or for other similar reasons. Often, the circuit is identified using two persons, typically equipped with walkie-talkies or similar communications equipment if the distance between the outlet and the breaker box is such that voice communication is impractical. A first person connects a load (e.g., a lamp) to the particular electrical outlet of interest. The second person then sequentially turns circuit breakers off and on until the first person indicates that the lamp or other load is no longer energized. If the circuit breaker associated with more than one outlet must be identified, the lamp or other indicating device must be moved to the second outlet and the process repeated. This procedure is both time consuming and labor intensive. 
     More recently, electrical testers have been developed that connect a signal-emitting device to the outlet being traced. A probe may then be used at the breaker box or similar termination point to identify which conductor in the breaker box carries the signal from the tester. While this procedure may offer a slight improvement over the method discussed hereinabove, it still requires either two people or multiple trips between the breaker box and the outlets when multiple outlets are being traced. One advantage, however, is that power to multiple circuits need not be systematically interrupted, thereby avoiding the need to reset clocks or other devices requiring a reset after power interruption thereto. 
     DISCUSSION OF THE RELATED ART 
     U.S. Pat. No. 5,565,784 for COAXIAL CABLE TESTING AND TRACING DEVICE, issued Oct. 15, 1996 to Lawrence L. DeRenne teaches an apparatus for identifying a number of different coaxial cables emanating from a central location. Up to eight coaxial cables may be terminated at their respective distal ends with a unique terminating device bearing a number between 0 and 7. Each of the terminating devices has a different characteristic impedance. A test apparatus at the central location is sequentially connected to the proximal end of the coaxial cables. Each cable is identified based upon the characteristic impedance of the terminator at the distal end thereof. Open circuits (i.e., coaxial cables having no termination) may also be identified. 
     U.S. Pat. No. 6,466,029 for POWER LINE TESTING DEVICE WITH SIGNAL GENERATOR AND SIGNAL DETECTOR, issued Oct. 15, 2002 to John E. Stroth et al. teaches a circuit identification system wherein a generated signal has a unique identification component. A signal is injected at an outlet in an electrical power distribution network within a building. A receiver at a breaker box is used to identify the circuit to which the transmitter is connected. 
     U.S. Pat. No. 6,525,665 for ELECTRICAL CIRCUIT TRACING DEVICE, issued Feb. 25, 2003 to Thomas M. Luebke et al. discloses another compact device wherein a signal is injected into an electrical power distribution network within a building from an electrical outlet to be traced. A receiver stored within the compact tester may then be used at the breaker box to identify the circuit to which the transmitter is connected. 
     U.S. Pat. No. 6,577,243 for METHOD AND APPARATUS FOR TRACING REMOTE ENDS OF NETWORKING CABLES, issued Jun. 10, 2003 to John Dannenmann et al. discloses an apparatus that may be attached to each end of a network cable. A signal injected at the first end of the cable is detected by a telltale indicator device at the other end of the cable. The system functions without interfering with the normal operation of the network to which the testing apparatus is attached. The DANNENMANN et al. testing apparatus also provides telephonic communication capability between technicians over the cable network being analyzed. 
     U.S. Pat. No. 6,850,073 for POWER CIRCUIT TESTER APPARATUS AND METHOD, issued Feb. 1, 2005 to Robert T. Elms et al. teaches an apparatus for identifying common wiring errors and for testing ground fault interrupters or other devices using user-selected tests. 
     None of the patents, taken singly or in any combination, is seen to teach or suggest the novel apparatus and method of identifying a circuit interrupter associated with a particular one of a plurality of electrical outlets connected to any one of a plurality of electrical circuits of the present invention. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided apparatus wherein uniquely identifiable electrical signals are injected into a plurality of deenergized electrical circuits at a central location, typically a circuit breaker panel. As used herein, the term circuit breaker is used to represent any electrical circuit-interrupting device, including, but not limited to circuit breakers and fuses. 
     Once the novel device is electrically connected to multiple deenergized branch circuits, a user may move from electrical outlet to electrical outlet and connect a circuit analysis box. The circuit analysis box contains a readout that indicates the circuit number (i.e., 1-n where n is the number of branch circuits simultaneously testable by the apparatus of the invention) to which the particular electrical outlet is connected. If a particular electrical outlet is accidentally connected to two branch circuits, the numbers of both the circuits to which the analyzer box is connected are both identified and displayed. 
     It is therefore an object of the invention to provide an apparatus for identifying a particular circuit breaker feeding a remotely disposed electrical outlet. 
     It is another object of the invention to provide an apparatus for identifying a particular circuit breaker feeding a remotely disposed electrical outlet wherein multiple circuits may simultaneously be injected with uniquely identifiable test signals. 
     It is an additional object of the invention to provide an apparatus for identifying a particular circuit breaker feeding a remotely disposed electrical outlet wherein an analysis box electrically connected at a particular electrical outlet identifies to which of the multiple circuits the outlet is connected. 
     It is a further object of the invention to provide an apparatus for identifying a particular circuit breaker feeding a remotely disposed electrical outlet wherein, when an outlet is connected to more than one electrical branch circuit, each of the more than one branch circuits may readily be identified. 
     It is a still further object of the invention to provide an apparatus for identifying a particular circuit breaker feeding a remotely disposed electrical outlet wherein a safety apparatus protects the apparatus from harm if one or more electrical circuits to which the apparatus is connected accidentally becomes energized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1  is a simplified system block diagram of an electrical circuit identification system of the prior art; 
         FIG. 2  is a simplified system block diagram showing the apparatus of the invention connected to an electrical power distribution network within a building; 
         FIG. 3  is a simplified functional block diagram of one embodiment of the electrical testing apparatus in accordance with the invention; and 
         FIG. 4  is a simplified functional block diagram of a digital readout for use with the electrical testing apparatus of  FIG. 3  in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides an apparatus and method for readily identifying to which of a plurality of deenergized electrical branch circuits within an electrical power distribution network an electrical outlet is connected. As used herein, the term “electrical power distribution network” includes only electrical branch circuits beyond a series of electrical circuit interrupters (for example, circuit breakers disposed in a circuit breaker panel). In a home or other small building, there may be only one such circuit breaker panel, often referred to as a “breaker box” whereas in a larger building, multiple circuit breaker panels (i.e., subpanels) may exist. 
     It is often necessary to deenergize an electrical circuit supplying electrical power to a particular electrical outlet or other load. As used herein, the term “electrical outlet” is intended to include any connector of terminal device providing power to a load, whether the load is pluggable or permanently wired to the electrical branch circuit. Circuit deenergization may be required, for example, to perform maintenance on the circuit, add a new outlet or other load to the circuit, or to respond to an emergency situation involving a branch circuit, etc. 
     Referring first to  FIG. 1 , there is shown a simplified system block diagram  100  of a portion of a typical electrical power distribution network undergoing testing in accordance with the prior art. A breaker panel  102  contains circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n , each controlling power flow to a branch circuit. Connected to circuit breaker  104   a  are electrical outlets  106   a ,  106   b ,  106   c . Likewise, connected to circuit breaker  104   b  are electrical outlets  108   a ,  108   b ,  108   c . Outlets  110   a ,  110   b , and  110   c  are connected to circuit breaker  104   c . Finally, outlet  112   a  is connected to circuit breaker  104   n.    
     An electrical signal source  112  is connected to electrical outlet  110   b.    
     A signal probe  114  is provided to determine to which of circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n  signal source  112  is connected. 
     In operation, all circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n  are typically opened to deenergize any electrical circuits of interest. Some embodiments of similar prior art tracing systems may be used with energized circuits. Once signal source  112  is connected to the desired electrical outlet  106   a ,  106   b , . . . ,  112   a , signal probe  114  is used to detect a signal at each circuit breaker  104   a ,  104   b ,  104   c , . . . ,  104   n  at the breaker box  102 . The circuit breaker  104   a ,  104   b ,  104   c , . . . ,  104   n  presenting the highest signal, not shown, to circuit probe  114  is the circuit breaker associated with the selected electrical outlet, in the illustrated case, electrical outlet  110   b  connected to circuit breaker  104   c.    
     This apparatus and the method of testing associated therewith are disadvantageous for several reasons. First, to determine which associated circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n  are connected to several outlets  106   a ,  106   b , . . . ,  112   a , numerous trips between the outlet  106   a ,  106   b , . . . ,  112   a  being traced and the breaker box  102  must be made. Also, each successive circuit breaker  104   a ,  104   b ,  104   c , . . . ,  104   n  must be probed until the desired circuit breaker  104   a ,  104   b ,  104   c , . . . ,  104   n  is located. In electrical wiring installations where cables run in close proximity to one another, it is also possible that similar signals may appear at more than one circuit breaker  104   a ,  104   b ,  104   c , . . . ,  104   n  due to inductive coupling. When this happens, additional testing may be required to definitively identify the correct circuit breaker  104   a ,  104   b ,  104   c , . . . ,  104   n  associated with a particular electrical outlet  106   a ,  106   b , . . . ,  112   a.    
     Referring now to  FIG. 2 , there is shown a simplified system block diagram  200  of a portion of a typical electrical power distribution network undergoing testing in accordance with the apparatus and method of the present invention. 
     A breaker panel  102  contains circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n . Connected to circuit breaker  104   a  are electrical outlets  106   a ,  106   b ,  106   c . Likewise, connected to circuit breaker  104   b  are electrical outlets  108   a ,  108   b ,  108   c . Outlets  110   a ,  110   b , and  110   c  are connected to circuit breaker  104   c . Finally, outlet  112   a  is connected to circuit breaker  104   n . Outlets  104   a ,  104   b , . . . ,  112   a  are connected to respective branch circuits associated with of circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n  as described hereinabove. 
     A multi-output electrical signal generating test apparatus  204  is equipped with output connections  206   a ,  206   b ,  206   c , . . . ,  206   n , each output  206   a ,  206   b ,  206   c , . . . ,  206   n  being connected to a respective one of the branch circuits connected to circuit breakers  104   a ,  104   b ,  104   c , . . . ,  104   n.    
     A digital readout  202  is connected to outlet  110   b  that is, in turn, connected to circuit breaker  104   c.    
     Referring now also to  FIG. 3 , there is shown a simplified functional block diagram of the inventive electrical signal generating test apparatus  204 , generally at reference number  300 . Electrical signal generating test apparatus  204  consists of a signal generator  302  and a unique address generator  304 . Outputs of signal generator  302  and unique address generator  304  are connected to input of a modulator/mixer  306 . 
     The output of modulator/mixer  306  is connected to the input of a sequencer  308 . Sequencer  308  has a plurality of outputs  310   a ,  310   b ,  310   c , . . . ,  310   n . Respective sequencer outputs  310   a ,  310   b ,  310   c , . . . ,  310   n  are connected to inputs to driver/isolator circuits  312   a ,  312   b ,  312   c , . . . ,  312   n . Output of drivers  312   a ,  312   b ,  312   c , . . . ,  312   n  form, respectively, outputs  206   a ,  206   b ,  206   c , . . . ,  206   n  as shown in  FIG. 2 . 
     A timer/controller  314  is operatively connected to unique address generator  304  and sequencer  308  to synchronize the switching of outputs  310   a ,  310   b ,  310   c , . . . ,  310   n  to match a correct unique address being generated by unique address generator  304 . 
     Referring now also to  FIG. 4 , there is shown a simplified functional block diagram  400  of digital readout  202  adapted for connection to one of electrical outlets  106   a ,  106   b , . . . ,  112   a . Digital readout  202  has an input connection  402 , typically terminating in a standard plug, not shown, for interconnection with a standard duplex or similar electrical outlet  110   b.    
     Input connection  402  is connected to the input of an interface and protection circuit  404 . The output of interface and protection circuit  404  is connected to a decoding circuit  406 . The output of decoding circuit  406  is, in turn, connected to the input of a display driver circuit  408 . 
     The output of display driver circuit  408  is connected to a numeric display  410 . While four digits are shown on numeric display  410 , it will be recognized that more or fewer digits may be utilized to accommodate and uniquely identify the maximum number of channels of electrical signal generating test apparatus  204 . It will be further recognized that other indicating means, for example, a series of LEDs, not shown, or other similar indicators may be used in place of numeric display  410  to indicate the channel to which digital readout  202  is connected. Consequently, the invention is not limited to the digital display chosen for purposes of disclosure. Rather, the invention includes any and all display technologies capable of uniquely indicating the channel to which digital display  204  is connected. 
     In the example chosen for purposes of disclosure, only four output circuits  206   a ,  206   b , . . . ,  206   d  are shown. It will be recognized that any number of outputs may be provided to meet a particular operating circumstance or environment. For example, an 8-output device may be suitable for typical home and small building testing. Devices having 16, 32 or more outputs may be useful for circuit tracing in industrial and commercial environments. Consequently, the invention in not considered limited to the four outputs chosen for purposes of disclosure but rather includes any number of outputs. 
     It will be further recognized that many technologies may be used to transmit uniquely identifiable signals across a plurality of channels. For example, a digital signal having a unique address encoded therein may be sent. Analog technologies using varying modulation frequencies, frequency shift keying, or many other technologies are believed to be known to those of skill in the art to implement the electrical testing apparatus  204  and digital readout  202  of the present invention. Consequently, specific technical details are not further discussed herein. 
     In an alternate embodiment of the novel apparatus of the present invention, a carrier current-based implementation may be used to trace energized circuits. One well-known implementation of a carrier-current communications is the so-called X10™ system. In the X10 system, household electrical wiring is utilized to send digital data between X10 devices. The digital data is encoded onto a 120 kHz carrier which is transmitted as bursts during the relatively quiet zero crossings of the 50 or 60 Hz AC alternating current waveform. One bit is typically transmitted at each zero crossing. The digital data consists of an address and a command sent from a controller to a controlled device. By sending unique X10 commands on each implemented channel of the novel signal generating test apparatus  204 , the remote digital readout  202  may readily identify the channel (i.e., the branch circuit of the electrical power distribution network) connected to the electrical outlet currently connected to the digital readout  202 . 
     Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
     Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.