Methods to detect when a human body contacts a predetermined portion of a machine are disclosed. The methods distinguish contact with a person from contact with other materials. The methods are particularly applicable in woodworking equipment such as power saws to detect contact between a person and the blade of the saw. Woodworking machines and memory devices for use in woodworking machines having safety systems designed to detect a dangerous condition between a human and a dangerous portion of the woodworking machine and to trigger some action to mitigate the dangerous condition are also disclosed.