Abstract:
A diagnostic testing system for use with two or more lighting systems of the High Intensity Discharge (HID) sports lighting type, wherein two or more lighting systems have their ballasts and diagnostic receptacles combined in a single ballast box at the base of a light pole for diagnostic access. Each lighting system has its own diagnostic receptacle electrically coupled to the other lighting system through a common block supplying power to the multi-system fixture. Each lighting system typically comprises at least one lamp, a ballast, a capacitor, and wiring interconnecting the lamp, ballast, and capacitor. Each diagnostic receptacle includes a continuity plug wired to maintain electrical connection to the common block while it is plugged in, and to cause its associated lighting system to be electrically isolated from the common block when the plug is removed. The diagnostic receptacles are adapted to receive a connector from a handheld diagnostic tester which maintains the electrical isolation from the common block during the diagnostic testing.

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 09/376,111 Aug. 13, 1999 now abandoned, which in turn is a continuation-in-part of U.S. application Ser. No. 08/633,079 filed Apr. 16, 1996 (now issued as U.S. Pat. No. 6,087,834 issued Jul. 11, 2000). 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an apparatus and method for testing the electrical components and wiring contained in a lighting system. 
     BACKGROUND OF THE INVENTION 
     Lighting systems used to illuminate athletic fields such as baseball fields, football fields, soccer fields and the like generally require the installation of light fixtures 20-120 feet above the ground. The light fixtures are often installed in arrays mounted at the top of a support pole. If any light fixture in a lighting array malfunctions, it may be difficult to determine the source of the failure without the use of a crane or ladder capable of reaching the light fixtures. 
     Lighting systems which use high intensity discharge (HID) lamps require the use of ballasts, capacitors, and various wires interconnecting the components of the lighting system. The failure of a lamp, ballast, capacitor, or wire may result in the failure of the lighting system. 
     Current test methods involve disconnecting each component to test them individually or swapping each component in and out of the lighting system to locate any defective components. This procedure requires electrical power to be applied to the system, and/or the use of special meters and the technical specifications for each component in order to determine the operability of each component. Furthermore, these tests may isolate problems in a particular component, but cannot detect problems in the wiring between the components without the use of a crane or boom truck to reach the light fixtures at the top of the pole. 
     Therefore, these previous attempts to locate faults in lighting systems are expensive, time-consuming, and must be performed by an electrician due to the requirement of a live power test. Additionally, the testing of HID lighting systems requires a specialized knowledge not held by all electricians. Thus, previous diagnostic testing systems and methods required a qualified electrician possessing the appropriate knowledge and special meters to test HID lighting systems. 
     SUMMARY OF THE INVENTION 
     The present diagnostic tester provides an apparatus for testing a lighting system having at least one lamp, a capacitor, a ballast, and various wires interconnecting these lighting system components. The diagnostic tester is capable of isolating the particular component or wiring in the lighting system producing the failure of the lamp, including failure of the lamp itself. The diagnostic tester connects to a diagnostic receptacle on a light pole easily accessible from the ground, rather than by a crane. The tests are performed with the lighting system power turned off and therefore may be performed by maintenance personnel, rather than an electrician. Since the power is off, the risk of injury due to electric shock is eliminated. 
     The components of the lighting system are not disconnected to perform the test, thereby making the testing easier, faster, and less expensive. Since the testing is performed at or near ground level, the use of a crane or similar apparatus is not required. Therefore, maintenance costs are reduced by permitting the quick identification of problem components. Additionally, the diagnostic tester permits the pretesting of light fixtures on the ground before installation on the lighting poles. 
     The diagnostic tester includes a connector adapted to operatively engage the diagnostic receptacle. Means are provided in the diagnostic tester for automatically and simultaneously testing the ballast, the capacitor, and the plurality of wires contained in the lighting system which connect the capacitor and the ballast to a single lamp. 
     A multivibrator circuit connected to any illuminatible device is used to test the capacitor and the illuminatible device blinks if the capacitor is functioning properly. A ballast test circuit includes an illuminatible device, such as a light emitting diode, and a driver for indicating whether the primary and the secondary of the ballast is functioning properly. A wiring test circuit includes at least a pair of light emitting diodes, and possibly an optional LED, along which associated drivers for indicating whether the plurality of wires in the lighting system connected between the ballast and the lamp are properly connected. 
     A continuity plug is capable of being inserted into the diagnostic receptacle when the diagnostic tester is disconnected from the diagnostic receptacle. The continuity plug, when inserted into the diagnostic receptacle, interconnects the lamp wiring, the ballast and the capacitor in a normal operable manner for normal operation of the lighting system. 
     When testing the lighting system, power is first disconnected from the lighting system. The LED&#39;s in the tester are then tested for proper operation. Next, the continuity plug is removed from the diagnostic receptacle and the diagnostic tester is connected to the receptacle. The capacitor is tested and its associated light emitting diode indicates whether the capacitor is functioning properly. Similar tests are performed on the ballast and wiring contained in the lighting system. 
     One of the LEDs in the tester may also be employed for indicating the continuity of a lighting system fuse. In this optional embodiment, a pair of terminals are mounted on the tester housing and are engageable with opposite ends of a lighting system fuse. The terminals are connected across the indicator such that the application of electrical power to the indicator and the terminals will enable the indicator to indicate the continuity or non-continuity of a fuse connected across the terminals by the on or off state of the indicator. 
     In another embodiment in which a lighting system employs a higher wattage lamp which requires the use of a separate ignitor, the diagnostic tester of the present invention may also be employed to test the ignitor by employing the same lighting wiring test procedures described herein. 
     After all tests have been performed, the diagnostic tester is disconnected from the diagnostic receptacle and the continuity plug is reinserted into the diagnostic receptacle. Finally, power is restored to the lighting system. 
     It is becoming increasingly common to mount two or more lighting systems on a single pole with the lighting systems (lamp, capacitor, ballast, and various wires interconnecting them) sharing a single ballast box. Power is often supplied to these dual-system, single ballast box fixtures via a “common block” power and fusing terminal. In a further form of the invention, a dual-system ballast box having a “common block” is provided with two diagnostic receptacles. Each diagnostic receptacle is electrically interconnected with the common block and one lighting system&#39;s lamp, capacitor, ballast, and wiring through a special continuity plug. The manner in which each diagnostic receptacle is wired into its respective lighting system and the common block through the continuity plug provides an automatic isolation of the system from the common block when the continuity plug is removed for testing. This isolation prevents the possibility of backfeed from the other ballast sharing the common block. Backfeed from the untested ballast can result in a false reading with respect to a particular component or wiring in the system being tested. 
     This dual-system, single-box diagnostic receptacle arrangement is tested with a diagnostic tester and connector modified from the single-system receptacle described above. The continuity plug for each dual system receptacle also differs from the single-system plug, and provides automatic isolation of an associated lighting system from the common block. 
     The dual-system receptacles are also useful for high wattage systems which may include extra capacitor and lamp wire connections in the ballast. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various features, advantages and other uses of the present invention will become more apparent by referring to the following description and drawings in which: 
     FIG. 1 is a perspective view of a diagnostic tester and diagnostic receptacle accoriding to the present invention; 
     FIG. 2 is a block diagram illustrating the interconnection of the diagnostic receptacle with various components of a lighting system; 
     FIG. 3 is a schematic diagram showing a continuity plug as used with the present invention and its electrical connections; 
     FIG. 4 is a schematic diagram of the inventive diagnostic tester and the lighting system components being tested; 
     FIG. 5 is a flow chart describing the overall procedure used when testing a lighting system according to the present invention; 
     FIG. 6 is a flow chart describing the procedure followed to determine which component or components of the lighting system are malfunctioning; 
     FIG. 7 is a pictorial representation of a modification to the diagnostic tester of the present invention according to an alternate embodiment of the present invention; 
     FIG. 8 is a partial schematic representation showing a modification to the schematic of FIG. 4 for use in conjunction with the modification depicted in FIG. 7; 
     FIG. 9 is a schematic diagram of an alternate light system circuit which can be tested by the diagnostic tester of the present invention; 
     FIG. 10 is a schematic representation of a dual-system ballast and diagnostic receptacle arrangement, wherein two lighting systems, each with its own ballast, capacitor, lamp and wiring, are provided with diagnostic receptacles contained in a single ballast box having a common block for power supply and fusing; 
     FIG. 10A is a schematic representation of the wiring of a continuity plug for the lefthand ballast and diagnostic receptacle in FIG. 10; 
     FIG. 10B is a schematic representation of the wiring of a continuity plug for the righthand ballast and diagnostic receptacle of FIG. 10; 
     FIG. 11 is a schematic representation of a dual-system ballast and diagnostic receptacle arrangement, similar to that of FIG. 10 but arranged to test a higher wattage fixture in which the ballast is provided with an additional capacitor and lamp connection; 
     FIG. 11A is a schematic representation of the wiring of a continuity plug for the lefthand diagnostic receptacle of FIG. 11; 
     FIG. 11B is a schematic representation of the continuity plug wiring for the righthand diagnostic receptacle of FIG. 11; 
     FIG. 12 is a perspective view of a dual-system ballast box containing two diagnostic receptacles according to the present invention, and a diagnostic tester according to the present invention plugged into one of the diagnostic receptacles in the ballast box; 
     FIG. 13 is a plan view of the pin terminals of the multi-pin diagnostic receptacle of FIG. 12, useful for the embodiments of FIGS. 10 and 11; 
     FIG. 14 is a close up view of the display panel of the diagnostic tester of FIG. 12; 
     FIG. 14A is a schematic diagram of the diagnostic tester of FIG. 14; 
     FIG. 14B is a table showing the connections between the circuit board pins of the diagnostic tester of FIG.  14 A and the connector of the tester; 
     FIG. 15 is an enlarged view of the righthand lighting system of FIG. 10; and 
     FIG. 16 is an enlarged view of the righthand lighting system of FIG.  11 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a diagnostic tester  10  according to the present invention is illustrated. Diagnostic tester  10  includes a housing  14  which contains the circuitry and components of the tester  10 . A push button switch  16  is used to activate the diagnostic tester  10  as described hereinafter. 
     A cable  18  extends from diagnostic tester  10  and has a male connector  20  at its terminal end. A ballast box  12 , which forms part of the lighting system to be tested and is typically mounted a short distance; i.e.,  10  feet, above grade on a light pole, includes a female multi-pin diagnostic receptacle  22 . Receptacle  22  is mounted within ballast box  12  and is electrically connected to the various components of the lighting system. Preferably, male connector  20  is a plug-in, quick-release connector which is designed to mate with diagnostic receptacle  22 . However, any other type of connector may be employed in the present diagnostic tester  10 . 
     Diagnostic receptacle  22  may be installed in ballast box  12  at the time of manufacture, or may be retrofitted into an existing ballast box already installed in a lighting system. To retrofit receptacle  22  to an existing ballast box, the receptacle  22  is connected as described below with reference to FIG. 2. A complete lighting installation may include several ballast boxes, with each ballast box having a diagnostic receptacle for each ballast therein. 
     Diagnostic tester  10  is a small hand-held device capable of being carried easily from one test location to another. Tester  10  has an internal power source and performs the tests automatically, thereby requiring only minimal interaction by the operator. 
     Separate illuminatible devices, such as light emitting diodes, (LED&#39;s  24 ,  26 ,  28 ,  30 , and  32 ) are used to indicate whether various components of the lighting system are functioning properly LED  29  is optional, as described hereafter. The function of each LED will be described below with reference to the schematic diagram illustrated in FIG.  4 . Although the present invention is described as utilizing light emitting diodes, it will be understood by those skilled in the art that various other types of indicator and illuminatible devices may be used to indicate proper component operation. Such other devices include various types of lights, meters, of display panels. 
     FIG. 2 illustrates a block diagram of the various components in the lighting system and their electrical interconnection with each other and with diagnostic receptacle  22 . Receptacle  22  is shown having a plurality of electrical connection points representing a plurality of electrical pins in the receptacle  22 . A ballast  33  is connected to pin  7  of diagnostic receptacle  22 . Additionally, ballast  33  is connected to a lamp  40 , and a negative line fuse  46 . A capacitor  34  has a first terminal  36  and a second terminal  38 . First capacitor terminal  36  is connected to pin  2  of diagnostic receptacle  22 , and second capacitor terminal  38  is connected to pin  1  of the diagnostic receptacle. An HID lamp  40  is mounted in lamp socket  42  which is connected to ballast  33  and pin  6  of diagnostic receptacle  22 . An optional resistor  43  is connected across the leads of the socket  42 . A positive line fuse  44  is connected to pin  4  of diagnostic receptacle  22 . Negative line fuse  46  is connected to ballast  33  as well as pin  3  of diagnostic receptacle  22 . 
     When the diagnostic tester  10  is not attached to diagnostic receptacle  22 , a continuity plug  48  is mated with the diagnostic receptacle  22 . FIG. 3 illustrates the electrical connections contained within continuity plug  48 . The pin numbers illustrated in FIG. 3 correspond with and electrically connect with the pin numbers illustrated in FIG. 2 with respect to diagnostic receptacle  22 . In particular, pins  4  and  5  are shorted together, thereby directing power from positive line fuse  44  directly to ballast  33 . Additionally, pins  7  and  2  are shorted together, thus connecting the first capacitor terminal  36  to ballast  33 . Finally, pins  1  and  6  are shorted together, thereby connecting second capacitor terminal  38  to lamp socket  42 . Therefore, when continuity plug  48  is mated with diagnostic receptacle  22 , the lighting system operates in a normal manner. 
     FIG. 4 illustrates a schematic diagram of the diagnostic tester  10  circuit as well as the lighting system components being tested. The left side of the schematic illustrated in FIG. 4 represents the components of the lighting system, and resembles the connections illustrated in FIG.  2 . Capacitor  34  is connected between pins  1  and  2  of diagnostic receptacle  22 . Pin  4  of diagnostic receptacle  22  is connected to positive line fuse  44 , and pin  8  of the diagnostic receptacle is connected to ground. Pins  3 ,  5 , and  7  are connected to ballast  33 , while pins  6  and  3  are connected to lamp  40 . 
     Male connector  20  on diagnostic tester  10  is a multi-pin connector which mates with diagnostic receptacle  22 . Preferably, connector  20  is a quick-release connector for simple connection with receptacle  22 . 
     A 9-volt battery  50  is connected between ground and switch  16 , thereby providing power (indicated by signal VBAT) to the tester circuit when the switch  16  is depressed. The various illuminatible devices or LED&#39;s  24 ,  26 ,  28 ,  29 ,  30  and  32  are biased by their respective drive transistors to a conductive state when VBAT power is applied thereto and the connector  20  is disconnected from the connector  22  on the receptacle  12 . This provides a check of the operability of each LED. 
     Pins  1  and  2  of connector  20  connect with capacitor terminals  36  and  38 . The circuit formed by NAND gates  52  and  54  as well as resistors  56 ,  58  creates a multi-vibrator circuit with capacitor  34 . When capacitor  34  is connected and functioning properly, the multi-vibrator circuit oscillates, thereby causing transistor  60  to turn on and off and causing LED  28  to blink. 
     If LED  28  does not blink, then the capacitor  34  is either defective or improperly connected. The rate at which LED  28  blinks is a function of the capacitance of capacitor  34 . The greater the capacitance of capacitor  34 , the slower LED  28  blinks. If LED  28  blinks extremely fast, capacitor  34  may be defective; i.e., the capacitor  34  may have a reduced capacitance. 
     The ballast continuity is tested using pins  5  and  7  of connector  20 . The circuit connected to pin  5  of connector  20  tests the ballast primary. If the ballast primary is functioning properly, a base current is conducted to transistor  62 , connecting the remainder of the circuit to ground. Therefore, the base of transistor  64  is connected to ground, thereby extinguishing LED  30 . Therefore, if LED  30  is illuminated, the ballast primary is malfunctioning, i.e., an open circuit. 
     Pin  7  of connector  20  is connected through a resistor to the base of transistor  68 , which receives a base current from the ballast secondary. If a base current is present, transistor  68  connects the remainder of the circuit to ground, thereby extinguishing LED  32 . An illuminated LED  32  indicates a malfunctioning ballast secondary. 
     The lamp  40  wiring extends from the ballast  33  and the receptacle  22  up along a light pole, not shown, to a junction connection with leads to the socket  42  in the light fixture. 
     If the lamp wiring is not connected properly, i.e., open at the socket  42 , transistor  76  will conduct through optional resistor  43 , thereby causing transistor  78  to conduct. The activation of transistor  78  causes signal VBAT to be applied to the inputs of NAND gates  80  and  82 . Since the inputs of NAND gates  80  and  82  are wired together as inverters, a logic HI signal is applied to the NAND gate inputs thereby generating a logic LO signal at the output and extinguishing optional LED  29 . Therefore, if LED  29  is off, a lamp socket wiring continuity fault is indicated. Conversely, if LED  29  is illuminated, proper lamp socket wiring is present. 
     In the preferred form, an HC 4011  integrated circuit is used to provide the four NAND gates  52 ,  54 ,  80 , and  82 . The two inputs of each NAND gate are electrically connected together, thereby causing each NAND gate to operate as an inverter. 
     As shown in FIG. 4, the positive power lead is connected through transistor  76  and LED&#39;s  24  and  26  to ground. A fuse  74  is connected to pin  3  of the connector  20  and to the junction of LED&#39;s  24  and  26 . LED  26  is connected through fuse  72  to ground in the receptacle  22 . Thus, LED  24  will be illuminated if the positive lamp wiring is properly connected; but when not illuminated, a short to the negative lead is present. Similarly, LED  26  will be illuminated if the negative lamp wiring is properly connected. When LED  26  is not illuminated a short of the negative wiring to ground is indicated. If both LED&#39;s  24  and  26  are not illuminated at the same time during a test, a short of the positive wiring to ground is present. 
     In operation, the lighting system is tested with the main power off, as shown in FIG. 5 at step  100 . At step  102 , before the tester  10  is connected to the receptacle  22 , switch  16  is depressed to test the operability of all of the LED&#39;s in the tester  10  by applying power to each LED to cause illumination of each operable LED. Next, continuity plug  48  is removed from diagnostic receptacle  22  at step  104 . Next, at step  106 , the diagnostic tester  10  is connected to diagnostic receptacle  22 , causing all diagnostic tests to be performed automatically at step  108 . 
     Depending on the lighting system components which do not pass the diagnostic tests, one or more LED&#39;s on the diagnostic tester will indicate a faulty component or faulty wiring by an “on” or “off” state as described above and as shown in FIG. 1 on the face of the tester  10 . If the diagnostic tester  10  indicates that all tests have passed, but one or more lamps in the lighting system are not functioning properly, this indicates that the lamp is at fault. 
     Thus, the tester  10  determines a lamp fault by process of elimination; i.e., if all other components and wiring are functioning properly, then the lamp must be the defective component. 
     At step  110 , the defective component or components are replaced or repaired. At step  112 , the diagnostic tester  10  is removed from diagnostic receptacle  22 , and continuity plug  48  is reinserted into the diagnostic receptacle at step  114 . Finally, at step  118 , main power to the light fixtures in the lighting system is turned on. 
     FIG. 6 is a flow chart which illustrates the procedure followed to determine which component or components of the lighting system are malfunctioning. In FIG. 6, step  120  corresponds to step  106  in FIG.  5 . 
     Similarly, step  146  corresponds to step  112  in FIG.  5 . Steps  122 - 144  are an expanded depiction of steps  108  and  110  in FIG.  5 . At step  120 , which corresponds to step  106  in FIG. 5, the diagnostic tester  10  is connected to the diagnostic receptacle  22 . Step  122  tests the lamp wiring, step  124  tests the capacitor, step  126  tests the ballast primary, and step  128  tests the ballast secondary. Although steps  122 - 128  are illustrated as four separate steps, these tests are performed simultaneously by the diagnostic tester  10 . As shown in FIG. 4, separate test circuits are provided to test each component of the system, thereby permitting simultaneous testing of the lighting components. The results of all diagnostic tests are indicated by the LED&#39;s on the diagnostic tester  10 . 
     At step  130  the operator determines whether the lamp wiring test passed by observing LED&#39;s  24 ,  26  and/or optional LED  29 . If LED  24  is illuminated or “on” the positive wire is properly connected. However, an off or not illuminated state for LED  24  indicates that the lamp positive wire is shorted to the negative wire. LED  26  provides a similar indication of the operability of the negative lamp wire, but with an off state indicating a short to ground. An “off” or non-illuminated state of both LED&#39;s  24  and  26  indicates that both that the positive wire is shorted to ground. If LED  29  is illuminated or on, then the lamp socket leads have continuity. If LED  29  is not illuminated, then there is a fault in the lamp leads at the lamp socket. If any part of the lamp wiring test did not pass, then the lamp wiring is repaired at step  132 , and the testing procedure is completed at step  146  by removing the diagnostic tester  10  from the diagnostic receptacle  22 . If the lamp wiring test passed at step  130 , then the operator next determines whether the capacitor test passed at step  134 . 
     If the capacitor  34  is functioning properly, LED  28  blinks on and off. If LED  28  does not blink, or blinks extremely fast, then the capacitor  34  is faulty. If the capacitor test did not pass, then the capacitor  34  is replaced at step  136 , and the testing is completed at step  146 . 
     If the capacitor test passed at step  134 , then the operator next determines whether the ballast primary test passed at step  138 . LED  30  is off if the ballast primary is functioning properly. If LED  30  is illuminated, then the ballast primary is open. If the ballast primary test failed, the ballast  33  is replaced at step  140 . 
     If the ballast primary test passed, then the user next determines whether the ballast secondary test passed at step  142 . If LED  32  is off, then the ballast secondary is functioning properly. An illuminated LED  32  indicates that a fault exists in the ballast secondary. If the ballast secondary test failed, then the ballast  33  is replaced at step  140 , and the lighting tests are completed. 
     If the ballast secondary test passed, and the lighting system is still inoperative, then the lamp  40  is replaced at step  144 , and the testing is completed at step  146 . Thus, the lamp  40  is tested by process of elimination. As shown in FIG. 6, the wiring, capacitor, ballast primary, and ballast secondary are tested first to determine proper operation. If any one or more of these components fail their respective test, then that particular component is repaired or replaced. If a lighting system is not functioning properly, but all four of the above-mentioned tests passed, the lamp  40  is determined to be at fault and is replaced. Therefore, if the lighting system is not working and all components except the lamp  40  are functioning properly, the lamp  40  must be the malfunctioning component in the lighting system. 
     Once the diagnostic tester  16  is connected to the diagnostic receptacle, the diagnostic tester  10  performs all tests automatically and simultaneously. The diagnostic tester  10  does not require any user input or user intervention, other than determining the status of the various LED&#39;s in the diagnostic tester  10  during testing. 
     It should also be noted that even though the present diagnostic tester  10  has been described as simultaneously testing each of the ballast  33 , the capacitor  34  and the lamp wiring, the diagnostic tester  10  can also be constructed to test any one or two of these components. 
     The diagnostic tester  10  of the present invention may also be modified to perform additional tests. As shown in FIGS. 7 and 8, the diagnostic tester  10  may be used to test the continuity of the fuses  44  and  46  used in the lighting system circuit. As is conventional, such fuses  44  and  46  are typically of the “midget” type and have two opposed conductive end caps or contacts. As shown in FIG. 7, a pair of terminals  81  and  83  are mounted on the housing of the diagnostic tester  10  at any convenient location. Thus, although the pair of terminals  81  and  83  are shown as being mounted on the top of the housing, it will be understood that the pair of terminals  81  and  83  may also be mounted on the bottom or any other surface of the housing. The terminals  81  and  83  are connected across the optional indicator or LED  29  as shown in FIG.  8 . 
     In use, the terminals  81  and  83  are engaged with opposite conductive ends of a fuse  44  or  46 . The “push-to-test” push button  16  is then depressed to supply power to the transistors  76  and  78 , shown in FIG. 4, and to the NAND gates  80  and  82  shown in FIGS. 4 and 8. If the fuse connected across the terminals  81  and  83  has continuity, the LED  29  will be in a non-illuminated state. However, if the fuse is defective or open, the LED  29  will be illuminated thereby providing indication of a defective fuse. It should be noted that the fuse test is conducted while the connector  18  is disconnected from the ballast box  12 . 
     The diagnostic tester  10  may also be used to detect the operability of an ignitor  90  shown in FIG. 9 which is used with a higher wattage lamp  40 ′, such as a 2000 watt lamp. Such a higher wattage lamp will require a capacitor  34  and a higher wattage ballast  33  which are interconnected with fuses  44  and  46  as shown in FIG.  9 . It will also be understood that a second series connected ballast  33  and capacitor  34  may be connected in parallel with the ballast  33  and capacitor  34  shown in FIG.  9 . 
     As the leads of the lamp  40 ′ are connected to the lamp post and common terminals of the ignitor  90 , the diagnostic tester  10  can also test the operability of the ignitor  90  in the same manner as the test described above for testing proper wiring of the lamp leads. The lamp socket connections are connected to the connector pins  3  and  6  as shown in FIG.  4  and can provide an indication of the operability or non-operability of the ignitor  90  by performing the same lamp wiring test described above. Thus, if the ignitor has failed, typically by shorting to ground, the lamp connection will be open causing transistors  76  and  78  to conduct as shown in FIG.  4  and described above. Conduction of transistor  78  through the NAND gates  80  and  82  causes the optional LED  29  to remain off when a continuity fault is present or to remain illuminated when proper ignitor  90  operation is detected. 
     Referring now to FIGS. 10-16, an embodiment of the invention is disclosed for diagnostic testing of multiple lighting systems installed on a single pole, and in particular for situations where two or more ballasts are contained in a single ballast box and share a “common block” for power supply and fusing in a manner which is known to those skilled in the art. 
     Referring first to FIG. 10, a first embodiment of a multiple-system diagnostic receptacle arrangement according to the invention is illustrated for a lower-wattage, “single ended” lamp fixture in which two lighting systems, each with its own lamp, ballast, capacitor and wiring, share a power supply through a common block and have their ballasts and diagnostic receptacles contained in a single ballast box on a light pole. FIGS. 10,  10 A and  10 B schematically represent the wiring for the two lighting systems, their respective diagnostic receptacles, and their continuity plugs. 
     Each lighting system in FIG. 10 is similar to that shown in FIG. 2, comprising an HID lamp  200 , a ballast  210 , one or more capacitors  220 , a power supply  230 , fuse  240  connected to the “hot” power wire, a multi-pin diagnostic receptacle  250 , and a mating continuity plug  260 . Each system is grounded at  270 . 
     Unlike the lighting system in FIG. 2, the two lighting systems in FIG. 10 share both a ballast box and their power supply through a common block at  230 . Use of the common block simplifies the main power disconnect and fusing for the lighting systems. 
     In the illustrated embodiment of FIG. 10, diagnostic receptacles  250  and their continuity plugs  260  are twelve-pin receptacles and plugs. This requires modification to the diagnostic tester  10  and its nine-pin connector  20  of FIG. 1 to accommodate the additional terminals and wiring, in particular the common block isolation feature described below. 
     It will also be understood by those skilled in the art that the number of pins in diagnostic receptacle  250  and plug  260  can vary depending on the wiring and components for a given lighting system. 
     The pin-receiving terminals in receptacle  250  can be assigned “numbers”, as can the mating pins in the continuity plug. It will be apparent from FIGS. 10,  10 A and  10 B that lefthand and righthand receptacles  250  and lefthand and righthand continuity plugs  260  are mirror images of one another for purposes of the drawing, but in an actual ballast box installation they will have the same left-right, up/down order and orientation of terminals and pins so that the diagnostic tester connector may be plugged into each in identical fashion. 
     The following description of the function and structure of one diagnostic receptacle  250  and associated continuity plug  260  applies equally to the other lighting system sharing common block  230  in the ballast box. 
     Referring to FIGS. 10 and 15, the wire connections between the various components of the lighting system (ballast, capacitors, lamp, fuse, common block) and the diagnostic receptacle  250  are schematically illustrated. Terminals  1  and  7  of the diagnostic receptacle are crimped together, reserved for use with higher wattage lamps as will be described below. Terminal  2  is connected to the voltage output of the ballast. Terminal  3  is connected to the common block  230 . Terminal  4  is connected to the ballast capacitor terminal. Terminal  5  is open. Terminal  6  is connected to one terminal of the capacitor  220 . Terminal  8  is connected to the fuse  240 . Terminal  9  is connected to the other terminal of capacitor  220 . Terminal  10  is connected to the lamp socket. Terminal  11  is connected to ground. Terminal  12  is connected to a common terminal at the ballast. Also, lamp  200  is connected to a common terminal at the ballast via line  201 . 
     As illustrated, each continuity plug is provided with “jumper” wires or other electrical connections between respective pairs of pins in the multi-pin array. As best shown in FIG. 15, there is a jumper between pins  8  and  2 ; between pins  6  and  4 ; between pins  9  and  7 ; between pins  10  and  1  and; between pins  12  and  3 . These jumpers in the illustrated embodiment comprise short loops of wire crimped or otherwise electrically secured to two of the pins. Pins  11  and  5  are open for purposes described below. 
     It will be understood from the foregoing that continuity plug  260  connects the various components and wiring of the lighting system when the continuity plug is inserted in diagnostic receptacle  250 . For example, the jumper between pins  4  and  6  in continuity plug  260  electrically interconnects terminals  4  and  6  of diagnostic receptacle  250 , thereby connecting one terminal of capacitor  220  to the ballast. 
     The above-illustrated and described wiring and jumper arrangement for the diagnostic receptacles  250  and their continuity plugs  260  provides an automatic isolation of each ballast  210  and its associated lighting system components from the common block  230  upon removal of continuity plug  260  from receptacle  250 , by breaking the electrical connection between terminals  3  and  12 . Combined with the wiring of the diagnostic tester connector  20 ′ and the circuitry of the diagnostic tester  10 ′ (best shown in FIGS.  14 A and  14 B), the ballast and associated lighting system being tested is isolated from common block  230  and the other lighting system in the ballast box. This feature is important because it prevents feedback or false readings from the ballast/lighting system not being tested. 
     In operation, each lighting system sharing common block  230  in FIG. 10 is tested in the same manner as depicted above with reference to FIGS. 1-9, in particular FIG.  5 . The main power is first turned off to common block  230 , such that both lighting systems sharing common block  230  are without power. Before the tester is connected to the receptacle, the tester itself is tested for operability of all of the LED&#39;s. Next, one of the continuity plugs  260  is removed from its receptacle  250 , automatically isolating that receptacle and lighting system from common block  230 . The diagnostic tester  10  is then connected to the open diagnostic receptacle  250 , causing all of the diagnostic tests of which the tester is capable to be performed automatically as described above. Isolation of the lighting system being tested from common block  230  and the untested lighting system sharing the common block is maintained throughout the diagnostic testing. 
     Depending on the lighting system components which do not pass the diagnostic tests, one or more LED&#39;s on the diagnostic tester will indicate a faulty component or faulty wiring by an “on” or “off” or blinking/flashing state as described above. If components or wiring are found to be defective, they are replaced or repaired. It will be understood that the procedure followed to determine which components of the lighting system being tested are malfunctioning is the same as that described in FIG. 6 above. The diagnostic tester is then removed from receptacle  250 , and continuity plug  260  is reinserted into the diagnostic receptacle. 
     At this point the testing procedure differs from that described above with reference to FIGS. 1-9. Rather than turning on main power to the fixture, the other continuity plug  260  is removed from the other diagnostic receptacle  250  associated with the common block, and the previously untested lighting system associated therewith is tested in identical fashion. 
     After the second continuity plug  260  is returned to its diagnostic receptacle  250 , main power to the lighting systems is turned back on. 
     Referring now to FIGS. 11,  11 A and  11 B, a slightly different pair of lighting systems and diagnostic receptacles is illustrated for a higher wattage (e.g., 2000 watt) lamp example. In the systems of FIG. 11, the lamp schematically illustrated is a “double-ended” commercially available lamp known to those skilled in the art, with wiring at both ends to accommodate an extra capacitor and lamp output from the ballast. In the lower wattage (e.g. 1500 watt) system of FIG. 10, the extra wires from terminals  1  and  7  are simply crimped together to form a closed loop; when the receptacle is used for a 2000 watt lamp, the crimped wires from  1  and  7  can be uncrimped and connected to the extra capacitor and lamp wire ballast terminals as shown in FIG.  11 . In the illustrated embodiment, ballasts  210  in FIG. 11 represent commercially available ballasts manufactured by Advance, which come pre-wired with four-wire (FIG. 10) or six-wire (FIG. 11) ballast connections depending on the bulb type and wattage. 
     The continuity plugs  260  for the 2000 watt array are identical to the continuity plugs  260  used in the 1500 watt lamp array of FIG.  10 . Only the wiring of the diagnostic receptacles has been changed, and only with respect to the crimped wires between terminals  1  and  7  in the receptacle. Otherwise, the operation of the diagnostic tester and the method for determining whether any of the components or wiring is faulty is identical to that described with reference to FIGS. 5 and 6 and FIG. 10 above. The only difference is the fact that there is an extra capacitor and lamp wire whose function needs to be checked, and this is achieved by simply uncrimping the wires from diagnostic receptacles  1  and  7  and tapping them into the ballast at the appropriate terminals. 
     It will also be understood in FIG. 11, that isolation of the common block upon removal of the continuity plugs is identical to the system illustrated in FIG.  10 . 
     Referring now to FIGS. 12-14, an actual dual-system ballast box according to the invention is illustrated generally at  12 ′ and is shown mounted a light pole  13  within ladder height from the ground (e.g., ten feet). FIGS. 12 and 14 also show a modified diagnostic tester  10 ′. Diagnostic tester  10 ′ is a modified tester  10 ′ similar to the tester in FIG. 1 contained in a convenient carrying case  11 , preferably formed from a suitable plastic, with a compartment for cable  18  and a modified diagnostic connector  20 ′. 
     In the modified diagnostic tester  10 ′ of FIG. 14, LED indicator lights  24 ′,  26 ′,  28 ′,  29 ′,  30 ′, fuse terminals  81 ′,  83 ′, and push-to-test button  16 ′ generally correspond to like reference numerals in FIG.  1 . As in FIG. 1, the test results will cause the same pattern of lighting effects on the face of tester  10 ′, with the exception that the “ballast primary” and “ballast secondary” LED indicator lights  30 ,  32  in the tester of FIG. 1 have been combined into one LED indicator light  30 ′ in tester  10 ′ of FIG.  14 . 
     Referring to FIGS. 14A and 14B, the circuitry and pin connections of diagnostic tester  10 ′ and connector  20 ′ are illustrated schematically to show the differences relative to the circuitry and pin connections in diagnostic tester  10  of FIG.  4 . 
     Accordingly, with the invention as shown in FIGS. 10-16, the ballasts and diagnostic receptacles for multiple lighting systems can be combined in a single box, with a common block power and fusing arrangement, and with the main power off can be individually tested with a diagnostic tester such as  10 ′ with assurance that the lighting system being tested is isolated from the common block and any possible backfeed from the other lighting system in that box. 
     It will be understood by those skilled in the art that while particular receptacle and continuity plug wiring arrangements for particular lighting systems have been illustrated in FIGS. 10 and 11 for purposes of explanation, and a particular diagnostic tester  10 ′ has been illustrated for the particular receptacle and continuity plug arrangements of FIGS. 10 and 11, those skilled in the art will be able to apply the multi-system, single ballast box, multiple diagnostic receptacle, common block isolation invention to different lighting systems with different wiring and components. These and other modifications will be apparent to those skilled&#39;in the art now that we have disclosed the specific embodiments of our invention.