Table saw with table sensor for sensing characteristic of workpiece

A table saw comprising:

• a table with an upper cutting surface;
• a motor-drive rotatable shaft positioned below the table;
• a blade for cutting a workpiece on the cutting surface, wherein:
• the blade is extendable at least partially above the cutting surface to cut the workpiece on the cutting surface;
• and
• the blade spins when the shaft rotates;
• a detection system for detecting a dangerous condition relative to the blade;
• a reaction system in communication with the detection system for taking a reaction in response to detection of the dangerous condition by the detection system;
• and
• a sensor for sensing a characteristic of the workpiece, wherein an output signal from the sensor is provided to the detection system for use by the detection system in detecting the dangerous condition.