Section 150.10. Arson in the third degree

1.  A  person  is  guilty  of  arson  in  the  third  degree  when  he
  intentionally damages a building or motor vehicle by starting a fire  or
  causing an explosion.
    2. In any prosecution under this section, it is an affirmative defense
  that  (a)  no  person  other  than  the  defendant  had  a possessory or
  proprietary interest in the building  or  motor  vehicle,  or  if  other
  persons  had  such  interests,  all of them consented to the defendant's
  conduct, and (b) the defendant's sole intent was to  destroy  or  damage
  the  building  or motor vehicle for a lawful and proper purpose, and (c)
  the defendant had no reasonable ground to believe that his conduct might
  endanger the life or safety of another person or damage another building
  or motor vehicle.
    Arson in the third degree is a class C felony.