Intellingent three-way and four-way dimmers

• US 20070007826A1
• Filed: 06/06/2006
• Published: 01/11/2007
• Est. Priority Date: 06/06/2005
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Mosebrook, Donald, Steffie, Jamie, Rogan, Christopher, Detmer, Steven, Keagy, Jon
• Granted Patent: US 7,687,940 B2
• Time in Patent Office: Days
• US Class Current: 307/139
• CPC Class Codes: H05B 39/041 the light-intensity of the source H05B39/08 takes precedence
• CPC Class Codes: H05B 39/08 by shifting phase of trigger voltage applied to gas-filled controlling tubes also in controlled semiconductor devices in converters H02M5/00; with regulation G05F1/44
• CPC Class Codes: H05B 39/086 with possibility of remote control
• CPC Class Codes: H05B 47/165 following a pre-assigned programmed sequence; Logic control [LC]
• CPC Class Codes: H05B 47/17 Operational modes, e.g. switching from manual to automatic mode or prohibiting specific operations
• CPC Class Codes: H05B 47/185 via power line carrier transmission
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A smart dimmer switch for control of a lighting load from an AC voltage source can replace any switch in a three-way or four-way lighting control system. The smart dimmer switch can be connected on the line-side or the load-side of a three-way system with a standard three-way switch in the other location. Further, the dimmer switch can replace a four-way switch in a four-way system and is operable to be coupled to two standard three-way switches. The dimmer switch includes either one or two semiconductor switches to control the intensity of the connected lighting load. The dimmer switch preferably includes a sensing circuit for detecting an electrical characteristic (i.e., either a voltage or a current) at a terminal of the dimmer to determine the state of the connected three-way switch(s) or four-way switch. The dimmer switch preferably controls the state of the semiconductor switch in response to either a toggle of any of the other switches in the system or an actuation of a toggle button of the dimmer switch.

Claims

1. A dimmer switch adapted to be coupled to a circuit including a power source, a load, and a single-pole double-throw three-way switch, the dimmer switch comprising:

first, second, and third electrical load terminals;

a controllably conductive device electrically coupled to the first, second, and third load terminals, the controllably conductive device having a conductive state in which the controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load, the controllably conductive device arranged such that when the controllably conductive device is in the conductive state, and the dimmer switch is coupled to the circuit, a current to the load flows between the first terminal and the second terminal or between the first terminal and the third terminal;

a sensing device electrically coupled to at least one of the second load terminal and the third load terminal, the sensing device operable to sense an electrical characteristic associated with the load terminal to which the sensing device is coupled;

a controller operably coupled to the controllably conductive device and to the sensing device, the controller operable to control the controllably conductive device in response to an output of the sensing device in accordance with the electrical characteristic; and

a power supply electrically coupled in shunt electrical connection with the controllably conductive device and operable to provide power to the controller.

2. The dimmer switch of claim 1, wherein the sensing device comprises a current sensing device.

3. The dimmer switch of claim 2, wherein the current sensing device comprises a current transformer.

4. The dimmer switch of claim 3, wherein the current transformer comprises a primary winding and a secondary winding, the primary winding of the current transformer being coupled between the controllably conductive device and at least one of the second and third load terminals, and the secondary winding of the current transformer being coupled so as to provide the output of the sensing device to the controller.

5. The dimmer switch of claim 4, wherein the current sensing device is operable to detect whether a charging current is flowing in the power supply.

6. The dimmer switch of claim 5, wherein the sensing circuit is operable to generate a control signal representative of whether the charging current is flowing in the power supply and the controller is operable to change the controllably conductive device between the conductive and non-conductive states in response to the control signal.

7. The dimmer switch of claim 1, wherein the controllably conductive device comprises a bidirectional semiconductor switch.

8. The dimmer switch of claim 7, wherein the bidirectional semiconductor switch comprises a triac.

9. The dimmer switch of claim 7, wherein the bidirectional semiconductor switch comprises two field-effect transistors in anti-series connection.

10. The dimmer switch of claim 1, further comprising:

a communication circuit adapted to receive a message including control information;

wherein the controller is operable to control the controllably conductive device in dependence on the control information.

11. The dimmer switch of claim 10, wherein the communication circuit receives the message via an IR communication link.

12. The dimmer switch of claim 10, wherein the communication circuit receives the message via an RF communication link.

13. The dimmer switch of claim 10, wherein the communication circuit receives the message via a wired communication link.

14. The dimmer switch of claim 1, further comprising:

a communication circuit adapted to transmit a message including feedback information representative of the state of the controllably conductive device and the output of the sensing device.

15. The dimmer switch of claim 14, wherein the communication circuit transmits the message via an RF communication link.

16. The dimmer switch of claim 14, wherein the communication circuit transmits the message via a wired communication link.

17. The dimmer switch of claim 1, further comprising:

a memory coupled to the controller.

18. The dimmer switch of claim 17, wherein the controller is operable to store in the memory state information representative of the state of the controllably conductive device and the output of the sensing device.

19. The dimmer switch of claim 18, wherein the controller is operable to recall the state information from the memory at power up.

20. The dimmer switch of claim 1, further comprising:

a visual display for providing feedback to a user of the dimmer switch.

21. The dimmer switch of claim 20, wherein the visual display comprises a plurality of light-emitting diodes.

22. The dimmer switch of claim 1, wherein the controller comprises a microprocessor.

23. The dimmer switch of claim 1, further comprising:

an actuator;

wherein the controller controls the controllably conductive device in response to an actuation of the actuator.

24. The dimmer switch of claim 1, wherein the load comprises a lighting load and the controller is operable to control the conductive state of the controllably conductive device so as to control a dimming level of the lighting load.

25. The dimmer switch of claim 1, further comprising:

a fourth electrical load terminal; and

a second sensing device electrically coupled to at least one of the first load terminal and the fourth load terminal, the sensing device operable to sense a second electrical characteristic associated with the load terminal to which the second sensing device is coupled;

wherein the controller is coupled to the second sensing device and is operable to control the controllably conductive device in response to an output of the second sensing device in accordance with the second electrical characteristic; and

wherein the controllably conductive device is arranged such that when the controllably conductive device is in the conductive state and the dimmer switch is coupled to the circuit, current to the load flows between the first load terminal and one of the second load terminal and the third load terminal, or between the fourth load terminal and one of the second load terminal and the third load terminal, depending on the output of the second sensing device.

26. A dimmer switch adapted to be coupled to a circuit including a power source, a load, and a single-pole double-throw three-way switch, the dimmer switch comprising:

first, second, and third electrical load terminals;

a first controllably conductive device having a conductive state in which the first controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load, the first controllably conductive device electrically coupled between the first load terminal and the second load terminal such that when the first controllably conductive device is in the conductive state, and the dimmer switch is coupled to the circuit, a current to the load flows between the first load terminal and the second load terminal;

a second controllably conductive device having a conductive state in which the second controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the second controllably conductive device is controlled so as to deliver substantially no power to the load, the second controllably conductive device electrically coupled between the first load terminal and the third load terminal such that when the second controllably conductive device is in the conductive state, and the dimmer switch is coupled to the circuit, the current to the load flows between the first load terminal and the third load terminal;

a controller operably coupled to the first and second controllably conductive devices and operable to cause the first and second controllably conductive devices to be in one of the conductive and non-conductive states; and

a power supply electrically coupled to the first, second, and third load terminals and operable to provide power to the controller.

27. The dimmer switch of claim 26, further comprising:

a first sensing device electrically coupled to the second load terminal and operable to sense a first electrical characteristic associated with the second load terminal; and

a second sensing device electrically coupled to the third load terminal and operable to sense a second electrical characteristic associated with the third load terminal;

wherein the controller is operable to control the first and second controllably conductive devices in response to an output of the first sensing device in accordance with the first electrical characteristic and in response to an output of the second sensing device in accordance with the second electrical characteristic.

28. The dimmer switch of claim 27, wherein the first sensing device is coupled in shunt electrical connection with the first controllably conductive device and the second sensing device is coupled in shunt electrical connection with the second controllably conductive device.

29. The dimmer switch of claim 28, wherein the first sensing device comprises a first impedance coupled in series electrical connection between the first load terminal and the second load terminal, and the second sensing device comprises a second impedance coupled in series electrical connection between the first load terminal and the third load terminal;

wherein the controller is responsive to a first voltage produced across the first impedance and to a second voltage produced across the second impedance.

30. The dimmer switch of claim 28, wherein the first sensing device comprises a first optocoupler having an input photodiode coupled in series electrical connection between the first load terminal and the second load terminal, and the second sensing device comprises a second optocoupler having an input photodiode coupled in series electrical connection between the second load terminal and the third load terminal;

wherein the controller is responsive to an output of the first optocoupler and an output of the second optocoupler.

31. The dimmer switch of claim 27, wherein the first and second sensing devices comprise current sensing devices.

32. The dimmer switch of claim 31, wherein the current sensing devices comprise current transformers.

33. The dimmer switch of claim 27, further comprising:

a communication circuit adapted to transmit a message including feedback information representative of the states of the first and second controllably conductive devices and the outputs of the first and second sensing devices.

34. The dimmer switch of claim 33, wherein the communication circuit transmits the message via an RF communication link.

35. The dimmer switch of claim 33, wherein the communication circuit transmits the message via a wired communication link.

36. The dimmer switch of claim 27, further comprising:

a visual display for providing feedback to a user of the dimmer switch.

37. The dimmer switch of claim 36, wherein the visual display comprises a plurality of light-emitting diodes.

38. The dimmer switch of claim 27, wherein the controller is operable to control both the first and second controllably conductive devices to be simultaneously non-conductive so as to deliver substantially no power to the load.

39. The dimmer switch of claim 26, further comprising:

a communication circuit adapted to receive a message including control information;

wherein the controller is operable to control the first and second controllably conductive devices in dependence on the control information.

40. The dimmer switch of claim 39, wherein the communication circuit receives the message via an IR communication link.

41. The dimmer switch of claim 39, wherein the communication circuit receives the message via an RF communication link.

42. The dimmer switch of claim 39, wherein the communication circuit receives the message via a wired communication link.

43. The dimmer switch of claim 26, wherein the first and second controllably conductive devices comprise bidirectional semiconductor switches.

44. The dimmer switch of claim 43, wherein the bidirectional semiconductor switches comprise triacs.

45. The dimmer switch of claim 43, wherein the bidirectional semiconductor switches comprise two field-effect transistors in anti-series connection.

46. The dimmer switch of claim 26, further comprising a memory coupled to the controller.

47. The dimmer switch of claim 46, wherein the controller is operable to store in the memory state information representative of the states of the first and second controllably conductive devices.

48. The dimmer switch of claim 47, wherein the controller is operable to recall the state information from the memory at power up.

49. The dimmer switch of claim 26, wherein the controller is operable to control the first and second controllably conductive devices to be conductive in a complementary basis, such that when the first controllably conductive device is conductive, the second controllably conductive device is non-conductive, and when the second controllably conductive device is conductive, the first controllably conductive device is non-conductive.

50. The dimmer switch of claim 26, wherein the controller comprises a microprocessor.

51. The dimmer switch of claim 26, further comprising:

an actuator;

wherein the controller controls the first and the second controllably conductive devices in response to an actuation of the actuator.

52. The dimmer switch of claim 26, wherein the load comprises a lighting load and the controller is operable to control the conductive states of the first and second controllably conductive devices so as to control a dimming level of the lighting load.

53. The dimmer switch of claim 26, wherein the power supply is coupled to the second terminal through a first diode and to the third terminal through a second diode.

54. A dimmer switch adapted to be coupled to a circuit including a power source, a load, a first single-pole double-throw switch, and a second single-pole double-throw switch, the dimmer switch comprising:

first, second, third, and fourth electrical load terminals;

a controllably conductive device electrically coupled between the first load terminal and the third load terminal for carrying a load current to the load, the controllably conductive device having a conductive state in which the controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load, the controllably conductive device arranged such that when the controllably conductive device is in the conductive state, and the dimmer switch is coupled to the circuit, a current through the load flows from one of the first load terminal and the second load terminal to one of the third load terminal and the fourth load terminal;

a first sensing device electrically coupled between the first load terminal and the second load terminal and adapted to carry the load current through the second load terminal, the first sensing device operable to sense a first electrical characteristic associated with the second load terminal;

a second sensing device electrically coupled between the third load terminal and the fourth load terminal and adapted to carry the load current through the fourth load terminal, the second sensing device operable to sense a second electrical characteristic associated with the fourth load terminal;

a controller operably coupled to the controllably conductive device and to the first and second sensing devices, the controller operable to control the controllably conductive device in response to an output of the first sensing device and an output of the second sensing device; and

a power supply coupled in shunt electrical connection with the controllably conductive device and operable to provide power to the controller.

55. The dimmer switch of claim 54, wherein the first and second sensing devices comprise current sensing devices.

56. The dimmer switch of claim 55, wherein the first sensing circuit is operable to generate a first control signal representative of whether a first current is flowing through the first current sensing device, and the second sensing circuit is operable to generate a second control signal representative of whether a second current is flowing through the second current sensing device;

wherein the controller is operable to change the controllably conductive device between the conductive and non-conductive states in response to the first control signal and the second control signal.

57. A dimmer switch adapted to be coupled to a circuit including a power source having a hot connection and a neutral connection, a load, and a single-pole double-throw three-way switch, the dimmer switch comprising:

first, second, and third electrical load terminals;

a controllably conductive device electrically coupled to the first, second, and third load terminals, the controllably conductive device having a conductive state in which the controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load, the controllably conductive device arranged such that when the controllably conductive device is in the conductive state and the dimmer switch is coupled to the circuit, a current to the load flows between the first load terminal and the second load terminal, or between the first load terminal and the third load terminal;

a sensing device electrically coupled to at least one of the second load terminal and the third load terminal, the sensing device operable to sense electrical continuity between the hot connection and the neutral connection of the power source through the controllably conductive device and the load;

a controller operably coupled to the controllably conductive device and to the sensing device, the controller operable to control the controllably conductive device in response to an output of the sensing device; and

a power supply electrically coupled in shunt electrical connection with the controllably conductive device and operable to provide power to the controller.

58. A method for controlling a load in a circuit comprising a power source, the load, a dimmer switch, and a single-pole double-throw three-way switch, the method comprising the steps of:

providing first, second, and third electrical load terminals on the dimmer switch;

electrically coupling a controllably conductive device to the first, second, and third load terminals, the controllably conductive device having a conductive state in which the controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load;

sensing an electrical characteristic associated with at least one of the second load terminal and the third load terminal; and

controlling the controllably conductive device in accordance with the sensed electrical characteristic, such that a current through the load flows between the first load terminal and the second load terminal, or between the first load terminal and the third load terminal.

59. The method of claim 58, wherein the step of sensing comprises sensing a current through one of the second load terminal and the third load terminal.

60. The method of claim 59, further comprising the step of:

coupling a current transformer in series electrical connection with at least one of the second load terminal and the third load terminal.

61. The method of claim 60, further comprising the step of:

coupling a power supply in shunt electrical connection with the controllably conductive device;

wherein the step of sensing further comprises detecting whether a charging current of the power supply is flowing through the current transformer.

62. The method of claim 61, further comprising the step of:

generating a control signal representative of whether the charging current is flowing through the current transformer;

wherein the step of controlling the controllably conductive device comprises changing the controllably conductive device between the conductive state and the non-conductive state in response to the control signal.

63. The method of claim 58, wherein the controllably conductive device comprises a bidirectional semiconductor switch.

64. The method of claim 63, wherein the bidirectional semiconductor switch comprises a triac.

65. The method of claim 63, wherein the bidirectional semiconductor switch comprises two field-effect transistors in anti-series connection.

66. The method of claim 58, further comprising the step of:

receiving a message including control information;

wherein the step of controlling the controllably conductive device comprises controlling the controllably conductive device in response to the control information.

67. The method of claim 66, wherein the step of receiving the message comprises receiving the message via an IR communication link.

68. The method of claim 66, wherein the step of receiving the message comprises receiving the message via an RF communication link.

69. The method of claim 66, wherein the step of receiving the message comprises receiving the message via a wired communication link.

70. The method of claim 58, further comprising the step of:

transmitting a message including feedback information representative of the state of the controllably conductive device and a result of the step of sensing.

71. The method of claim 70, wherein the step of transmitting the message comprises transmitting the message via an RF communication link.

72. The method of claim 70, wherein the step of transmitting the message comprises transmitting the message via a wired communication link.

73. The method of claim 58, further comprising the step of:

storing in a memory state information representative of the state of the controllably conductive device and the sensed electrical characteristic.

74. The method of claim 73, further comprising the step of:

recalling the state information from the memory at power up.

75. The method of claim 58, further comprising the step of:

providing feedback to a user of the dimmer switch via a visual display.

76. The method of claim 75, wherein the visual display comprises a plurality of light-emitting diodes.

77. The method of claim 58, wherein the step of controlling the controllably conductive device further comprises controlling the controllably conductive device in response to an actuation of an actuator of the dimmer switch.

78. The method of claim 58, wherein the load comprises a lighting load and the step of controlling the controllably conductive device further comprises controlling the conductive state of the controllably conductive device so as to control a dimming level of the load.

79. The method of claim 58, further comprising the steps of:

providing a fourth electrical load terminal on the dimmer switch; and

sensing a second electrical characteristic associated with at least one of the first load terminal and the fourth load terminal;

wherein the step of controlling the controllably conductive device further comprises controlling the controllably conductive device in accordance with the sensed second electrical characteristic.

80. A method for controlling a load in a circuit comprising a power source, the load, a dimmer switch, and a single-pole double-throw three-way switch, the method comprising the steps of:

providing first, second, and third electrical load terminals on the dimmer switch;

electrically coupling a first controllably conductive device between the first load terminal and the second load terminal, the first controllably conductive device having a conductive state in which the first controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the controllably conductive device is controlled so as to deliver substantially no power to the load, the first controllably conductive device arranged such that when the first controllably conductive device is in the conductive state, a current through the load flows between the first load terminal and the second load terminal;

electrically coupling a second controllably conductive device between the first load terminal and the third load terminal, the second controllably conductive device having a conductive state in which the second controllably conductive device is controlled so as to deliver a desired amount of power to the load and a non-conductive state in which the second controllably conductive device is controlled so as to deliver substantially no power to the load, the second controllably conductive device arranged such that when the second controllably conductive device is in the conductive state, the current through the load flows between the first load terminal and the third load terminal; and

controlling the first and second controllably conductive devices between the conductive state and the non-conductive state.

81. The method of claim 80, further comprising the steps of:

sensing a first electrical characteristic associated with the second load terminal; and

sensing a second electrical characteristic associated with the third load terminal;

wherein the step of controlling the first and second controllably conductive devices comprises controlling the first and second controllably conductive devices in accordance with the sensed first electrical characteristic and the sensed second electrical characteristic.

82. The method of claim 81, further comprising the steps of:

coupling a first sensing device in shunt electrical connection with the first controllably conductive device for sensing the first electrical characteristic; and

coupling a second sensing device in shunt electrical connection with the second controllably conductive device for sensing the second electrical characteristic.

83. The method of claim 82, wherein the first sensing device comprises a first impedance coupled in series electrical connection between the first load terminal and the second load terminal, and the second sensing device comprises a second impedance coupled in series electrical connection between the second load terminal and the third load terminal;

wherein the step of controlling the first and second controllably conductive devices comprises controlling the first and second controllably conductive devices in accordance with a first voltage produced across the first impedance and a second voltage produced across the second impedance.

84. The method of claim 82, wherein the first sensing device comprises a first optocoupler having an input photodiode coupled in series electrical connection between the first load terminal and the second load terminal, and the second sensing device comprises a second optocoupler having an input photodiode coupled in series electrical connection between the second load terminal and the third load terminal;

wherein the step of controlling the first and second controllably conductive devices comprises controlling the first and second controllably conductive devices in accordance with an output of the first optocoupler and an output of the second optocoupler.

85. The method of claim 81, wherein the step of sensing a first electrical characteristic comprises sensing a first current through the second load terminal and the step of sensing a second electrical characteristic comprises sensing a second current through the third load terminal.

86. The method of claim 81, further comprising the step of:

transmitting a message including feedback information representative of the states of the first and second controllably conductive devices, the sensed first electrical characteristic, and the sensed second electrical characteristic.

87. The method of claim 86, wherein the step of transmitting the message comprises transmitting the message via an RF communication link.

88. The method of claim 86, wherein the step of transmitting the message comprises transmitting the message via a wired communication link.

89. The method of claim 81, further comprising the step of:

providing feedback to a user of the dimmer switch via a visual display.

90. The method of claim 89, wherein the visual display comprises a plurality of light-emitting diodes.

91. The method of claim 81, wherein the step of controlling the first and second controllably conductive devices comprises controlling both the first and second controllably conductive devices to be non-conductive so as to deliver substantially no power to the load.

92. The method of claim 80, further comprising the step of:

receiving a message including control information;

wherein the step of controlling the first and second controllably conductive devices comprises controlling the first and second controllably conductive devices in accordance with the control information.

93. The method of claim 92, wherein the step of receiving the message comprises receiving the message via an IR communication link.

94. The method of claim 92, wherein the step of receiving the message comprises receiving the message via an RF communication link.

95. The method of claim 92, wherein the step of receiving the message comprises receiving the message via a wired communication link.

96. The method of claim 80, wherein the first and second controllably conductive devices comprise bidirectional semiconductor switches.

97. The dimmer switch of claim 96, wherein the bidirectional semiconductor switches comprise triacs.

98. The dimmer switch of claim 96, wherein the bidirectional semiconductor switches comprise two field-effect transistors in anti-series connection.

99. The method of claim 81, further comprising the step of:

storing in a memory state information representative of the states of the first and second controllably conductive devices, the sensed first electrical characteristic, and the sensed second electrical characteristic.

100. The method of claim 99, further comprising the step of:

recalling the state information from the memory at power up.

101. The method of claim 80, wherein the step of controlling the first and second controllably conductive devices comprises controlling the first and second controllably conductive devices to be conductive in a complementary basis, such that when the first controllably conductive device is conductive, the second controllably conductive device is non-conductive, and when the second controllably conductive device is conductive, the first controllably conductive device is non-conductive.

102. The method of claim 80, wherein the step of controlling the first and second controllably conductive devices further comprises controlling the first and second controllably conductive devices in response to an actuation of an actuator of the dimmer switch.

103. The method of claim 80, wherein the load comprises a lighting load and the step of controlling the first and second controllably conductive devices further comprises controlling the conductive states of the first and second controllably conductive devices so as to control a dimming level of the lighting load.

104. The method of claim 80, further comprising the step of:

coupling a power supply from the first load terminal to the second load terminal through a first diode and to the third terminal through a second diode.

105. A system for supplying power to a load from a power source comprising:

a single-pole double-throw (SPDT) three-way switch comprising a first fixed contact, a second fixed contact, and a movable contact adapted to be coupled to either the power source or the load, the SPDT three-way switch having a first state in which the movable contact is contacting the first fixed contact and a second state in which the movable contact is contacting the second fixed contact; and

a dimmer switch comprising;

a first load terminal adapted to be coupled to either the power source or the load to which the SPDT three-way switch is not coupled to;

a second load terminal coupled to the first fixed contact of the SPDT three-way switch;

a third load terminal coupled to the second fixed contact of the SPDT three-way switch;

a first controllably conductive device electrically coupled such that when the first controllably conductive device is in a conductive state, a desired amount of power is capable of being delivered to the load, and when the first controllably conductive device is in a non-conductive state, substantially no power is capable of being delivered to the load;

a controller electrically coupled to the first controllably conductive device and operable to control the first controllably conductive device; and

a power supply electrically coupled in shunt electrical connection with the first controllably conductive device and operable to provide power to the controller;

wherein when the SPDT three-way switch is in the first state, the controller is operable to control the first controllably conductive device such that a current to the load flows through the second load terminal when the first controllably conductive device is in the conductive state; and

wherein when the SPDT three-way switch is in the second state, the controller is operable to control the first controllably conductive device such that the current to the load flows through the third load terminal when the controllably conductive device is in the conductive state.

106. The system of claim 105, wherein the first controllably conductive device is electrically coupled between the first load terminal and the second load terminal such that when the first controllably conductive device is in the conductive state, a current to the load flows between the first load terminal and the second load terminal;

wherein the dimmer switch further comprises a second controllably conductive device having a conductive state in which the second controllably conductive device is controlled such that a desired amount of power is capable of being delivered to the load and a non-conductive state in which the second controllably conductive device is controlled such that substantially no power is capable of being delivered to the load, the second controllably conductive device electrically coupled between the first load terminal and the third load terminal such that when the second controllably conductive device is in the conductive state, current to the load flows between the first load terminal and the third load terminal.

107. The system of claim 106, wherein the dimmer switch further comprises:

a first sensing device electrically coupled to the second load terminal and operable to sense a first electrical characteristic associated with the second load terminal; and

a second sensing device electrically coupled to the third load terminal and operable to sense a second electrical characteristic associated with the third load terminal;

wherein the controller is operable to control the controllably conductive device in response to an output of the first sensing device in accordance with the first electrical characteristic and in response to an output of the second sensing device in accordance with the second electrical characteristic.

108. The system of claim 107, wherein the controller is operable to determine whether the SPDT three-way switch is in the first state or the second state in response to the outputs of the first and second sensing devices.

109. The system of claim 108, wherein the dimmer switch further comprises a memory coupled to the controller.

110. The system of claim 109, wherein the controller is operable to store in the memory state information representative of the states of the first and second controllably conductive devices and the state of the SPDT three-way switch.

111. The system of claim 110, wherein the controller is operable to recall the state information from the memory at power up.

112. The system of claim 108, wherein the dimmer switch further comprises a communication circuit adapted to transmit a message including feedback information representative of the states of the first and second controllably conductive devices and the state of the SPDT three-way switch.

113. The system of claim 108, wherein the load comprises a lighting load and the dimmer switch further comprises a visual display for providing to a user of the dimmer switch feedback information representative of a dimming level of the lighting load, the feedback information dependent on the states of the first and second controllably conductive devices and the state of the SPDT three-way switch.

114. The system of claim 107, wherein the controller is operable to control both the first and second controllably conductive devices to be non-conductive when the load is not powered.

115. The system of claim 106, wherein the first and second controllably conductive devices comprise bidirectional semiconductor switches.

116. The system of claim 106, wherein the dimmer switch further comprises a communication circuit adapted to receive a message including control information;

and

wherein the controller is operable to control the first and second controllably conductive devices dependent on the control information.

117. The system of claim 106, wherein the controller is operable to control the first and second controllably conductive devices to be conductive in a complementary basis, such that when the first controllably conductive device is conductive, the second controllably conductive device is non-conductive, and when the second controllably conductive device is conductive, the first controllably conductive device is non-conductive.

118. The system of claim 105, wherein the dimmer switch further comprises a sensing device electrically coupled to at least one of the second load terminal and the third load terminal, the sensing device operable to sense an electrical characteristic associated with the load terminal to which the sensing device is coupled;

wherein the first controllably conductive device is arranged such that when the first controllably conductive device is in the conductive state, a current to the load flows between the first load terminal and the second load terminal, or between the first load terminal and the third load terminal.

119. The system of claim 118, wherein the controller is operable to determine whether the SPDT three-way switch is in the first state or the second state in response to the output of the sensing device.

120. The system of claim 119, wherein the sensing device comprises a current sensing device.

121. The system of claim 120, wherein the current sensing device comprises a current transformer.

122. The system of claim 119, wherein the dimmer switch further comprises a memory coupled to the controller.

123. The system of claim 122, wherein the controller is operable to store in the memory state information representative of the state of the first controllably conductive device and the state of the SPDT three-way switch.

124. The system of claim 123, wherein the controller is operable to recall the state information from the memory at power up.

125. The system of claim 119, wherein the dimmer switch further comprises a communication circuit adapted to transmit a message including feedback information representative of the state of the first controllably conductive device and the state of the SPDT three-way switch.

126. The system of claim 119, wherein the load comprises a lighting load and the dimmer switch further comprises a visual display for providing to a user of the dimmer switch feedback information representative of a dimming level of the lighting load, the feedback information dependent on the state of the first controllably conductive device and the state of the SPDT three-way switch.

127. The system of claim 118, wherein the first controllably conductive device comprises a bidirectional semiconductor switch.

128. The system of claim 118, wherein the dimmer switch further comprises a communication circuit adapted to receive a message including control information;

and

wherein the controller is operable to control the first controllably conductive device dependent on the control information.

129. The system of claim 105, wherein the controller comprises a microprocessor.

130. The system of claim 105, wherein the dimmer switch further comprises an actuator;

wherein an actuation of the actuator causes the controller to control the first controllably conductive device.

131. The system of claim 105, wherein the load comprises a lighting load and the controller is operable to control the conductive state of the first controllably conductive device so as to control a dimming level of the lighting load.

132. The system of claim 105, wherein the first terminal of the dimmer switch is coupled to the power source and the movable contact of the SPDT three-way switch is coupled to the load.

133. The system of claim 105, wherein the first terminal of the dimmer switch is coupled to the load and the movable contact of the SPDT three-way switch is coupled to the power source.

134. A system for supplying power to a load from a power source comprising:

a first single-pole double-throw (SPDT) three-way switch comprising a first fixed contact, a second fixed contact, and a first movable contact adapted to be coupled to the power source, the first SPDT three-way switch having a first state in which the first movable contact is contacting the first fixed contact and a second state in which the first movable contact is contacting the second fixed contact;

a second SPDT three-way switch comprising a third fixed contact, a fourth fixed contact, and a second movable contact adapted to be coupled to the load, the second SPDT three-way switch having a third state in which the second movable contact is contacting the third fixed contact and a fourth state in which the second movable contact is contacting the fourth fixed contact; and

a dimmer switch comprising a first load terminal coupled to the first fixed contact of the first SPDT three-way switch, a second load terminal coupled to the second fixed contact of the first SPDT three-way switch, a third load terminal coupled to the third fixed contact of the second SPDT three-way switch, and a fourth load terminal coupled to the fourth fixed contact of the second SPDT three-way switch;

wherein the dimmer switch is operable to control the power delivered to the load.

135. The system of claim 134, wherein the dimmer switch further comprises:

a controllably conductive device having a conductive state in which the controllably conductive device is controlled such that a desired amount of power is capable of being delivered to the load and a non-conductive state in which the controllably conductive device is controlled such that substantially no power is capable of being delivered to the load;

arranged such that when the controllably conductive device is in the conductive state, a current to the load flows between one of the first load terminal and the second load terminal and one of the third load terminal and the fourth load terminal;

a first sensing device electrically coupled to at least one of the first load terminal and the second load terminal, the sensing device operable to sense a first electrical characteristic associated with the load terminal to which the first sensing device is coupled;

a second sensing device electrically coupled to at least one of the third load terminal and the fourth load terminal, the sensing device operable to sense a second electrical characteristic associated with the load terminal to which the second sensing device is coupled; and

a controller electrically coupled to the controllably conductive device and operable to control the controllably conductive device in response to an output of the first sensing device and an output of the second sensing device.

136. The system of claim 135, wherein the controller is operable to determine whether the first SPDT three-way switch is in the first state or the second state in response to the output of the first sensing device and whether the second SPDT three-way switch is in the third state or the fourth state in response to the output of the second sensing device.