I use red heat lamps BUT they are firmly wired in place and set so even if my absent minded hubby leaves the lid open they can't start a fire. He once set a lit infared bulb to one side as he worked on a lizard tank and before I realized what he'd done the side of the tank literally exploded from the hot bulb pressing againsth the glass. Thankfully no one, even the lizard, was hurt, though my Hubby had to buy anohter expensive custom tank.
The closest I've come to a fire was my cat sleeping in top of the brooder and getting hot enough to start some fur scorching.