Which of the following is NOT a common cause of residential fires?

High humidity is not typically considered a common cause of residential fires. While high humidity can contribute to a range of discomforts and issues within a home, it does not directly lead to ignition or fire incidents.

In contrast, several common fire causes within residences include heating equipment, smoking materials, and electrical malfunctions. Heating equipment, such as space heaters and furnaces, can easily ignite flammable materials if they are not maintained or positioned correctly. Smoking materials, like cigarettes, are a leading cause of fire when they are improperly disposed of or when they ignite combustible items. Electrical malfunctions, including faulty wiring or overloaded circuits, can create sparks and heat that may ignite surrounding materials.

Understanding the common causes of fires helps in creating effective prevention strategies, making it clear that high humidity, although it can create other issues, does not pose a direct risk of fire ignition.