Lighting control device for use with lighting circuits having three-way switches

A method for controlling an electrical load in a circuit comprising an AC power source, the load, a lighting control device, and a single-pole double-throw three-way switch, the 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 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, the method comprising the steps of:

• providing a first load terminal on the lighting control device, the first load terminal adapted to be coupled to either the AC power source or the load to which the three-way switch is not coupled;
• providing a second load terminal on the lighting control device, the second load terminal adapted to be coupled to the first fixed contact of the three-way switch;
• providing a third load terminal on the lighting control device, the third load terminal adapted to be coupled to the second fixed contact of the three-way switch;
• coupling a controllably conductive device to the first, second, and third load terminals, such that the controllably conductive device is operable to conduct a load current from the AC power source to the load;
• sensing an electrical characteristic associated with the third load terminal;
• and
• controlling the controllably conductive device in response to the sensed electrical characteristic, so as to control the amount of power delivered to the load by rendering the controllably conductive device conductive to conduct the load current through the second terminal when the three-way switch is in the first state, and by rendering the controllably conductive device conductive to conduct the load current through the third load terminal when the three-way switch is in the second state.

A system for supplying power from an AC power source to an electrical load, the system comprising:

• a single-pole double-throw 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 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 lighting control device comprising:
• a first load terminal adapted to be coupled to either the AC power source or the load to which the three-way switch is not coupled to;
• a second load terminal coupled to the first fixed contact of the three-way switch;
• a third load terminal coupled to the second fixed contact of the three-way switch;
• a first controllably conductive device coupled to the first, second, and third load terminals to conduct a load current from the AC power source to the load;
• and
• a controller operably coupled to the first controllably conductive device for controlling the controllably conductive device, so as to control the amount of power delivered to the load by rendering the first controllably conductive device conductive to conduct the load current through the second terminal when the three-way switch is in the first state, and by rendering the first controllably conductive device conductive to conduct the load current through the third load terminal when the three-way switch is in the second state.