WO1994011939A1

WO1994011939A1 - Safety shut-off for modular office panels

Info

Publication number: WO1994011939A1
Application number: PCT/US1993/010972
Authority: WO
Inventors: Russell E. Zemen, Jr.; Robert D. Timmerman
Original assignee: Group Dekko International
Priority date: 1992-11-13
Filing date: 1993-11-12
Publication date: 1994-05-26
Also published as: AU5603994A

Abstract

A safety shut-off switch assembly (22) is provided for deenergizing power supplied to a plurality of wall panels (10 and 12) which are electrically coupled together and configured to form a plurality of office cubicles. The safety shut-off switch assembly (22) includes a relay (50) for electrically coupling a selected wall panel (10 or 12) to a main power entry (51) of the building to provide electrical power to the plurality of electrically coupled wall panels (52), and a circuit for detecting and responding to a signal from a trigger source (36) and for generating an output signal in response to a trigger event. The assembly (22) also includes a deenergizing circuit for opening the relay (50) to shut off electrical power supplied to the plurality of wall panels (10 and 12) upon receipt of the signal from the trigger source (36). A delay circuit (42) is also provided for delaying transmission of the output signal to the deenergizing circuit by a predetermined delay time period.

Description

SAFETY SHUT-OFF FOR MODULAR OFFICE PANELS

Background and Summary of the Invention

The present invention relates to a safety shut- off switch. More particularly, the present invention relates to an assembly for automatically deenergizing or shutting off power supplied to a plurality of electrified wall panels in the event of a catastrophe or emergency during which the wall panels might fall over. Modern offices often use free-standing partitions or wall panels to form individual office cubicles in an open office environment. These cubicles provide a proper working environment while maintaining versatility and mobility for unrestricted office organization and expansion. It is essential that each of the cubicles formed by the wall panels is provided with electrical power. Therefore, various modular wiring systems which permit adjacent wall panels to be coupled together electrically have been developed. Wiring harnesses for electrically coupling adjacent wall panels are well known. Typically, a wiring harness has an elongated metal channel through which electrical conductors run. Electrical power is supplied to the harnesses from a main power supply entry. Harnesses located within adjacent wall panels are electrically coupled so that more than one wall panel can be powered from a single power supply entry.

Problems can arise with the electrified wall panels in the event of an earthquake, tornado, fire or other emergency. Modular wall panels can fall over during a such an emergency situation. This can expose live electrical wires which can create a hazardous condition for workers in the area of the wall panels. In particular, the live electrical wires can create the potential for electrical shock or for fires in the office building. Conventional tip-over protection for modular wall panels includes a break-away wire located within each wiring harness that breaks or disconnects the electrical path through the wiring harness when adjacent wall panels exceed a predetermined relative deflection. When the wire inside the wiring harness breaks, the wall panel is disconnected from the power supply.

In the event of an emergency, the safety shut-off switch of the present invention sounds a loud alarm and a reset/interrupt button is illuminated. A user has up to 2.5 minutes to interrupt the alarm before power to the office panels is disconnected. This delay time is adjustable. After power has been disconnected to the wall panels, the alarm continues to be audible and a locating light on the unit is activated. This light may be designed to flash on and off if desired. Pressing the reset/interrupt button after power is disconnected resets the device and restores power to the wall panels.

Advantageously, the present invention shuts off electrical power supplied to the plurality of wall panels in the event of an emergency. Therefore, the present invention reduces the likelihood that workers in the area of the wall panels will be exposed to live electrical wires if the wall panels fall over during the emergency. According to one aspect of the present invention, a safety shut-off switch assembly is provided for deenergizing power supplied to a plurality of wall panels which are electrically coupled together and configured to form a plurality of office cubicles. The safety shut-off switch assembly includes means for electrically coupling a selected wall panel to a main power entry of the building to provide electrical power to the plurality of electrically coupled wall panels, and means for detecting and responding to a signal from a trigger source and for generating an output signal in response to a trigger event. The assembly also includes means for deenergizing electrical power supplied to the plurality of wall panels upon receipt of the output signal generated in response to the trigger event. The deenergizing means is coupled between the main power entry and the selected wall panel.

In the illustrated embodiment, the coupling means includes a relay coupled to the main power entry. The relay is movable from a first closed position to permit the main power entry to supply electrical power to the plurality of wall panels to a second open position to shut off electrical power supplied to the plurality of wall panels by the main power entry. The deenergizing means includes means for moving the relay from the first position to the second position in response to the signal generated in response to the trigger event. The moving means is coupled to the means for detecting and responding to a signal from a trigger source and to the relay. The illustrated embodiment also includes a manual reset switch coupled to the moving means for moving the relay from the second position to the first position to restore electrical power to the plurality of wall panels.

According to another aspect of the present invention, the safety shut-off switch assembly includes means for delaying transmission of the signal generated in response to the trigger event to the moving means by a predetermined delay time period. The delaying means includes an interrupt switch which can be actuated by an operator during the predetermined delay time period to prevent the moving means from moving the relay from the first position to the second position. The delaying means transmits the signal generated in response to the trigger event to the moving means after the predetermined delay time period expires if the interrupt switch was not actuated by the operator. The delaying means is coupled between the means for detecting and responding to a signal from a trigger source and the moving means. The delaying means includes an audible alarm for indicating detection of the signal generated in response to the trigger event.

In the illustrated embodiment, the delaying means includes a counter and a multi-position switch coupled to the counter for setting the predetermined delay time. The switch has an output coupled to the deenergizing means.

Additional objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Brief Description of the Drawings

Figure 1 is a perspective view of the present invention illustrating a safety shut-off switch coupled to a load bearing wall or structural column of a building for shutting off electrical power to a plurality of wall panels adjacent the safety shut-off switch.

Figure 2 is a block diagram illustrating the components of the safety shut-off switch of the present invention.

Figure 3 is a schematic drawing illustrating details of the safety shut-off switch.

Detailed Description of the Drawings

Referring now to the drawings. Figure 1 illustrates adjacent modular wall panels 10 and 12 for dividing an office into a plurality of office cubicles or work stations. Each wall panel 10 and 12 includes a plurality of electrical receptacles 14 for providing electrical power to work stations in the office. Power is supplied to the electrical receptacles 14 from a power supply line 16 through wiring harnesses located in race ways 18 and 20 of wall panels 10 and 12, respectively. Wiring harnesses in adjacent wall panels 10 and 12 are electrically coupled so that a single power supply line 16 can be used to provide electrical power to a plurality of wall panels.

Although only two wall panels 10 and 12 are illustrated, it is understood that a plurality of wall panels may be electrically coupled together and powered by the single power supply line 16. As discussed above, problems can arise with wall panels 10 and 12 in the event of an emergency such as an earthquake, tornado, or fire. Wall panels 10 and 12 are typically not secured to a ceiling of the building. Therefore, wall panels 10 and 12 may fall over during an emergency situation. This can expose electrical wires located in race ways 18 and 20 to workers in the area of the wall panels. Therefore, the present invention provides a safety shut-off switch 22 which shuts off electrical power supplied to the wall panels 10 and 12 through power supply line 16 in the event of an emergency.

Safety shut-off switch 22 of the present invention is coupled to a structural column or load bearing wall 24 of the building by brackets 26. The main power supply entry 27 from the building is coupled to safety shut-off switch at 22 through supply conduit 28. Power supply line 16 is connected to an output of safety shut-off switch 22 to provide electrical power the wall panels 10 and 12. Safety shut-off switch at 22 includes an outer housing 30 and a reset button 31 accessible through outer housing 30 for restoring power to wall panels 10 and 12 after the danger passes. In addition, safety shut-off switch 22 includes a test signal generator 32 and a light 33.

Details of safety shut-off switch 22 are illustrated in Figures 2 and 3. Safety shut-off switch 22 can be activated by any trigger source 36 including an RF signal, a transducer, or a test/panic button. If an RF signal or transducer is used, conversion circuitry is provided for converting the RF signal or transducer output into a DC voltage. Trigger source 36 can be an earthquake detector, a tornado detector, a fire detector, or any other trigger source for generating a signal in response to a trigger event for deenergizing the plurality of wall panels 10 and 12.

Figure 2 illustrates a block diagram of the safety shut-off switch 22 of the present invention. As illustrated in Figure 2, a trigger source 36 generates a signal for deactivating the plurality of wall panels. Trigger source 36 is coupled to a latch 38. Upon receiving the signal from trigger source 36, latch 38 generates a signal to activate an alarm 40. Alarm 40 indicates that the signal from trigger source 36 has been received. In addition, latch 38 is coupled to a delay circuit 42. Delay circuit 42 provides a predetermined time delay before deenergizing the plurality of wall panels. During the predetermined delay time, an operator can reset the switch 22 using a reset/interrupt button 31 to prevent deactivation of the wall panels.

The length delay time can be selected by an operator as illustrated at block 46. Delay circuit 42 also includes a timing circuit 48 for determining the time at which the signal from the trigger source 36 is passed to relays 50 for deenergizing the power supplied to the wall panels. Relays 50 receive an AC power input from the main power supply of the building as illustrated at block 51. Power from relays 50 is supplied to the plurality of wall panels as illustrated at block 52. When the signal from trigger source 36 is received from delay circuit 42, relays 50 open to break the supply of power to wall panels. When the wall panels are deenergized, a light is illuminated as illustrated at block 53. Details of safety shut-off switch 22 are illustrated in Figure 3. Trigger source 36 is coupled to first and second input terminals of a NAND gate 54 which provides the input of latch 38. An output from NAND gate 54 is coupled to a first input of NAND gate 56. An output from NAND gate 56 is coupled to a first terminal of a 33K resistor 58. The second terminal of resistor 58 is coupled through a 2.2 μf capacitor 60 to ground. The second terminal of resistor 58 is also coupled to first and second input terminals of NAND gate 62. An output from NAND gate 62 is coupled to a second input terminal of NAND gate 56. Preferably, NAND gates 54, 56 and 62 are CD4093 Schmitt- trigger NAND gates available from National Semiconductor. The output from NAND gate 62 provides the output of latch 38.

When the voltage signal from trigger source 36 is below a pre-set low voltage of about 3V, the output from NAND gate 62 is high (logical one) at about 5V DC. If the voltage signal from trigger source 36 is about 3V or higher, the output from NAND gate 62 is a logical zero.

The output from NAND gate 62 is coupled to the reset input at pin 11 of a 14-bit binary counter 64. Illustratively, counter 64 is a CD4020B counter available from National Semiconductor. Counter 64 is used as the delay circuit 42 for the present invention. The reset input of binary counter 64 is normally high, meaning that all the outputs of the counter are low and the clock input is free-running. The clock input frequency is 60 Hz. When counter 62 is triggered by an input from trigger source 36 and latch 38, the reset is low and counter 64 begins counting. The time delay depends upon which output has been previously selected by an operator to be coupled to relay circuitry by a multi-position switch 66. Up to 2.5 minutes of delay may be set for the delay circuit 42. The selected counter output is fed back to the clock input of 14-bit counter 64 through diode 68. This sets the clock input of counter 64 to a constant 5V DC level and also locks the selected output 5V DC.

A timing circuit 70 is provided which generates a 60 Hz clock signal. Line and neutral conductors are connected across primary winding 72 of the transformer 74. End terminal 76 of secondary winding 78 is coupled to ground. End terminal 80 of secondary winding 78 is coupled to a first terminal of a 10K resistor 82. A second terminal of resistor 82 is coupled to the cathode of diode 84. The anode of diode 84 is coupled to ground. The second terminal of resistor 82 is also coupled to the face of transistor 86. Illustratively, transistor 86 is a 2N3904 transistor available from Motorola. The emitter of transistor 86 is coupled to ground. The collector of transistor 86 is coupled through a 100K resistor 88 to a +5V supply voltage. Collector of transistor 86 is also coupled through a 33K resistor 90 to the clock input at pin 10 of counter 64. The output from multi-position switch 66 is coupled to a relay network 92. Specifically, output from multi-position switch 66 is coupled through a 10K resistor 94 to the base of transistor 96. The base of transistor 96 is also coupled through a 33K resistor 98 to ground. Illustratively, transistor 96 is a 2N3904 transistor available from Motorola. The emitter of transistor 96 is coupled through a 33K resistor 100 to ground. The emitter of transistor 96 is also coupled to the base of transistor 102. Illustratively, transistor 102 is a MPS2222A transistor available from Motorola. The emitter of transistor 102 is coupled to ground. The collector of transistor 102 is coupled to a first terminal of light 104. A second terminal of light 104 is coupled to a +20V supply voltage. The collector of transistor 96 is coupled through a 3.3K resistor 106 to a +20V supply voltage. The collector of transistor 96 is also coupled to the base of a transistor 108. Transistor 108 is illustratively a MPS2222A transistor. The emitter of transistor 108 is coupled to the anode of a diode 110. The cathode of diode 110 is coupled to ground. The collector of transistor 108 is coupled to the anode of diode 112. The cathode of diode 112 is coupled to a +20V supply voltage. Illustratively, diodes 110 and 112 are 1N4003 diodes available from Motorola

Relay network 92 includes four normally open relays 114, 116, 118, and 120. The anode of diode 112 is coupled to the negative (-) input terminal of relay 116. The cathode of diode 112 is coupled to the (+) positive input terminal of relay 116. All the negative (-) input terminals of relays 114, 116, 118 and 120 are coupled together. All the positive (+) input terminals of relays 114, 116, 118 and 120 are also coupled together.

Power is supplied to an input side terminal 122 of each relay 114, 116, 118 and 120 from a main power supply of the building. Power is output from relays on line 124 to various selected wall panels in the building. Each of the fpur relays 114, 116, 118 and 120 can power a series of wall panels. During normal operation, power is supplied to relays 114, 116, 118 and 120 to close the normally open relays and supply power to the wall panels.

When the output from trigger source 36 indicates that an emergency situation has occurred, the output from NAND gate 54 is a logical zero and the output from NAND gate 56 is a logical one. The output from NAND gate 56 is coupled through a 3.3K resistor 126 to the base of transistor 128. Illustratively, transistor 128 is a MPS2222A transistor. The emitter of transistor 128 is coupled to ground. The collector of transistor 128 is coupled to a first terminal of light 130. The second terminal of light 130 is coupled to a +20V supply voltage. The collector of transistor 128 is also coupled to a first terminal of a 270 ohm resistor 132. A second terminal of resistor 132 is coupled to the anode of Zener diode 134. The cathode of Zener diode 134 is coupled to a +20V supply voltage. The second terminal of resistor 132 is also coupled a first terminal of an alarm buzzer 136. A second terminal of alarm 136 is coupled to the +20V supply voltage. When trigger source 36 indicates an emergency situation, the output from NAND gate 62 is low, thereby triggering the reset of counter 64. Counter 64 then begins counting until a predetermined delay time set by multi- position switch is met. After the predetermined delay time, a +5V supply voltage is supplied to base of transistor 96. During the delay time set by switch 66, an operator can depress reset switch on 138 in order to prevent the safety switch 22 from shutting off power to the plurality of wall panels. Reset switch 138 is a normally open switch. When switch 138 is depressed, terminals 140 and 142 of switch 138 are coupled to ground. Terminal 142 of switch 138 is coupled through a 1M resistor 144 to ground. Terminal 142 of switch 138 is also coupled to the first terminal of a IK resistor 146. A second terminal of resistor 146 is coupled to both inputs of NAND gate 62. When reset 138 is pressed, a logical zero is supplied to the input of NAND gate 62. Therefore, a logical one or high output is provided to the reset of counter 64 which stops the counter and prevents the +5V supply voltage from being delivered to the base of transistor 96.

If reset switch 138 is not pressed during the predetermined delay time, the +5V supply voltage is supplied to the base of transistor 96 after the predetermined time delay expires. This causes light 104 to illuminate. In addition, current is drawn through diode 112 and transistor 108 so that current no longer supplied to relay 116. Therefore, each of the normally open relays 114, 116, 118 and 120 move from a closed position to the normally open position. This breaks the power supply from the supply line to deenergize the plurality of wall panels. By deenergizing the power supply to the wall panels after trigger source 36 indicates an emergency or test situation, the safety shut-off switch 22 of the present invention reduces the likelihood that live wires will be exposed if the wall panels should happen to fall over during the emergency.

From the preceding description of the preferred embodiment, it is evident that the objects of the invention are obtained. Although the invention has been described and illustrated in detail, it is understood that the same is intended by way of illustration and example only, and is not be taken by way of limitation. The spirit and scope of the invention are to be limited only by the terms of the appended claims.

Claims

1. A safety shut-off switch assembly for deenergizing power supplied to a plurality of wall panels which are electrically coupled together, the safety shut- off switch assembly comprising: means for electrically coupling a selected wall panel to a main power entry of the building to provide electrical power to the plurality of electrically coupled wall panels; means for detecting and responding to a signal from a trigger source and for generating an output signal in response to a trigger event; and means for deenergizing electrical power supplied to the plurality of wall panels in response to the output signal generated in response to the trigger event, the deenergizing means being coupled between the main power entry and the selected wall panel.

2. The assembly of Claim 1, wherein the coupling means includes a relay coupled to the main power entry, the relay being movable from a first closed position to permit the main power entry to supply electrical power to the plurality of wall panels to a second open position to shut off electrical power supplied to the plurality of wall panels by the main power entry.

3. The assembly of Claim 2, wherein the deenergizing means includes means for moving the relay from the first position to the second position in response to the output signal generated in response to the trigger event, the moving means being coupled to the means for detecting and responding to a signal from a trigger source and to the relay.

4. The assembly of Claim 3, further comprising a manual reset switch coupled to the moving means for moving the relay from the second position to the first position to restore electrical power to the plurality of wall panels.

5. The assembly of Claim 3, further comprising means for delaying transmission of the output signal generated in response to the trigger event to the moving means by a predetermined delay time period.

6. The assembly of Claim 5, wherein the delaying means includes an interrupt switch which can be actuated by an operator during the predetermined delay time period to prevent the moving means from moving the relay from the first position to the second position, the delaying means transmitting the signal generated in response to the trigger event to the moving means after the predetermined delay time period expires if the interrupt switch was not actuated by the operator, the delaying means being coupled between the means for detecting and responding to a signal from a trigger source and the moving means.

7. The assembly of Claim 5, wherein the delaying means includes an audible alarm for indicating detection of the signal from the trigger source.

8. The assembly of Claim 5, wherein the delaying means includes a counter and a multi-position switch coupled to the counter for setting the predetermined delay time, the switch having an output coupled to the deenergizing means.

9. A safety shut-off switch assembly for deenergizing power supplied to a plurality of wall panels which are electrically coupled together, the safety shut- off switch assembly comprising: a relay for electrically coupling a selected wall panel to a main power entry of the building to provide electrical power to the plurality of electrically coupled wall panels, the relay being movable from a first closed position to supply electrical power to the wall panels to a second open position to shut off electrical power supplied to the wall panels; means for detecting and responding to a signal from a trigger source and for generating an output signal in response to a trigger event; means for moving the relay from the first closed position to the second open position in response to the output signal generated in response to the trigger event, the moving means being coupled to the means for detecting and responding to a signal from a trigger source and to the relay; and means for delaying transmission of the output signal generated in response to the trigger event to the moving means by a predetermined delay time period. 10. The apparatus of Claim 9, wherein the delaying means includes an interrupt switch which can be actuated by an operator during the predetermined delay time period to prevent the moving means from moving the relay from the first closed position to the second open position, the delaying means transmitting the output signal generated in response to the trigger event to the moving means after the predetermined delay time period expires if the interrupt switch is not actuated by the operator, the delaying means being coupled between the means for detecting and responding to a signal from a trigger source and the moving means.

11. The apparatus of Claim 9, wherein the means for detecting and responding to a signal from a trigger source comprises a latch coupled between the trigger source and the delaying means, the latch being turned off by the signal from the trigger source to start the predetermined delay time period.

12. The apparatus of Claim 9, wherein the delaying means includes an alarm for indicating detection of the signal from the trigger source. 13. The apparatus of Claim 9, further comprising means for automatically resetting the apparatus after a temporary loss of power at the main power entry.

14. The apparatus of Claim 9, further comprising a manual reset switch coupled to the moving means for moving the relay from the second position to the first position to restore electrical power.

15. The apparatus of Claim 9, wherein the delaying means includes a counter and a multi-position switch coupled to the counter for setting the predetermined delay time, the switch having an output coupled to the moving means.

16. A safety shut-off switch apparatus for deenergizing power supply to a plurality of wall panels electrically coupled together, the safety shut-off switch apparatus comprising: means for electrically coupling a selected wall panel to a main power supply of the building to provide electrical power to the plurality of electrically coupled wall panels, the coupling means being coupled between the main power entry and the selected wall panel; means for detecting and responding to a signal from a trigger source and for generating an output signal in response to a trigger event; means for deenergizing electrical power supplied to the plurality of wall panels in response to the output signal generated in response to the trigger event; and a delay circuit for delaying transmission of the output signal generated in response to the trigger event to the deenergizing means by predetermined delay time period.

17. The apparatus of Claim 16, wherein the delay circuit includes an interrupt switch which can be actuated during the predetermined delay time period to prevent transmission of the output signal generated in response to the trigger event to the deenergizing means. 18. The apparatus of Claim 16, wherein the means for detecting and responding to a signal from a trigger source comprises a latch coupled between the trigger source and the delay circuit. 19. The apparatus of Claim 16, wherein the coupling means includes a relay coupled to the main power entry, the relay being movable from a first position to permit the main power entry to supply electrical power to the plurality of wall panels to a second position to shut off electrical power supplied to the plurality of wall panels by the main power entry.

20. The apparatus of Claim 16, wherein the delay circuit includes a counter and a multi-position switch coupled to the counter for setting the predetermined delay time, the switch having an output coupled to the deenergizing means.

21. The apparatus of Claim 16, wherein the deenergizing means further includes a switch coupled to a relay for opening the relay in response to a signal from the delaying means.

AMENDED CLAIMS

[received by the International Bureau on 1 April 1994 ( 01.04.94) ; original claim 17 cancelled; original claims 9 and 16 amended; claims 18-21 unchanged but renumbered as claims 17-20 other claims unchanged (4 pages) ] position to restore electrical power to the plurality of wall panels .

9. A safety shut-off switch apparatus for deenergizing power supplied to a plurality of wall panels which are electrically coupled together, the safety shut- off switch apparatus comprising: a relay for electrically coupling a selected wall panel to a main power entry of the building to provide electrical power to the plurality of electrically coupled wall panels, the relay being movable from a first closed position to supply electrical power to the wall panels to a second open position to shut off electrical power supplied to the wall panels; means for detecting and responding to a signal from a trigger source comprising at least one of an earthquake detector, a tornado detector, and a fire detector and for generating an output signal in response to a trigger event; means for moving the relay from the first closed position to the second open position in response to the output signal generated in response to the trigger event, the moving means being coupled to the means for detecting and responding to a signal from a trigger source and to the relay; and means for delaying transmission of the output signal generated in response to the trigger event to the moving means by a predetermined delay time period.

10. The apparatus of Claim 9, wherein the delaying means includes an interrupt switch which can be actuated by an operator during the predetermined delay time period to prevent the moving means from moving the relay from the first closed position to the second open position, the delaying means transmitting the output signal generated in response to the trigger event to the moving means after the predetermined delay time period expires if the interrupt switch is not actuated by the operator, the delaying means being coupled between the means for detecting and responding to a signal from a trigger source and the moving means.

12. The apparatus of Claim 9, wherein the delaying means includes an alarm for indicating detection of the signal from the trigger source.

13. The apparatus of Claim 9, further comprising means for automatically resetting the apparatus after a temporary loss of power at the main power entry.

16. A safety shut-off switch apparatus for deenergizing power supply to a plurality of wall panels electrically coupled together, the safety shut-off switch apparatus comprising: means for electrically coupling a selected wall panel to a main power supply of the building to provide electrical power to the plurality of electrically coupled wall panels, the coupling means being coupled between the main power entry and the selected wall panel; means for detecting and responding to a signal from a trigger source and for generating an output signal in response to a trigger event; means for deenergizing electrical power supplied to the plurality of wall panels in response to the output signal generated in response to the trigger event; and a delay circuit for delaying transmission of the output signal generated in response to the trigger event to the deenergizing means by predetermined delay time period, the delay circuit including an interrupt switch which can be actuated during the predetermined delay time period to

A FMΠFO SHEET (ARTICLE 19) prevent transmission of the output signal generated in response to the trigger event to the deenergizing means, thereby maintaining the supply electrical power to the plurality of electrically coupled wall panels.

17. The apparatus of Claim 16, wherein the means for detecting and responding to a signal from a trigger source comprises a latch coupled between the trigger source and the delay circuit.

18. The apparatus of Claim 16, wherein the coupling means includes a relay coupled to the main power entry, the relay being movable from a first position to permit the main power entry to supply electrical power to the plurality of wall panels to a second position to shut off electrical power supplied to the plurality of wall panels by the main power entry.

19. The apparatus of Claim 16, wherein the delay circuit includes a counter and a multi-position switch coupled to the counter for setting the predetermined delay time, the switch having an output coupled to the deenergizing means.

20. The apparatus of Claim 16, wherein the deenergizing means further includes a switch coupled to a relay for opening the relay in response to a signal from the delaying means.

AMENDED SHEET (ARTICLE 19]