First, manufacturers identify which of the product’s energy sources can cause pain or injury (i.e. electrical, mechanical, or thermal) to users, taking into account whether the users are the general public, people who have received instruction or skilled users. Secondly, they assess the effects (painful, injury-inducing, etc) and combustion potential (not likely/possible/likely) of each source. Third, they identify the necessary safeguards (equipment, instructional or installation, for example), and finally test those safeguards using performance or construction-based criteria.