Can a light bulb start a fire? Absolutely! Any kind of light bulbs, from fluorescent to incandescent to halogen, can cause fires if they are not used correctly. Here are the specific features on common household light bulbs that can potentially lead to fire.
If a light bulb is used too often, then its bottle wiring (the wires you see inside the bulb) can turn brittle because of the excess heat. This is especially possible when the wattage that is being demanded of the bulb exceeds the wattage of the bulb itself. Of course, those brittle wiring conditions can lead to the bulb catching fire. To prevent this, do your best to not run any light bulb more than it needs to be run. For pet heat lamps, there are special light bulbs that can handle the wattage; invest in those bulbs, because they will be able to keep up with the demand.
When a light bulb is located inside a glass lighting fixture, it is at risk of catching fire. The main reason for this is that the heat is not able to dissipate as well; the enclosure traps some of the heat, and it can build up to the point of the bulb overheating and catching fire. To minimize the risk, choose a bulb that matches the wattage specification on your lighting fixture (this should be printed on the box, or even on the fixture itself).
When a light bulb is running constantly, and it is connected to a fixture that is powered by the wires inside your walls and ceilings, that is a big fire risk. Often, the bottle wiring of a common light bulb cannot handle the high wattage that is coming through the infrastructure wiring. To reduce the risk of fire, do not leave any overhead lights inside the home on overnight. If you are going out of town, do not leave the indoor lights on the entire time (instead, invest in home automation so you can control your lights with your smartphone!).
How can a light bulb start a fire? As you can see, there are several possibilities. Minimize your risk of fire by following these tips for light bulb safety.