The distance combustible materials must be kept from a heat source is closest to which value?

• A. 5 feet
• B. 20 feet
• C. 10 feet
• D. 15 feet

Answer: (C)

Keeping combustibles away from a heat source is about reducing the chance that heat will ignite them. The needed separation depends on how hot the source is and how flammable the materials are, but a practical minimum commonly used in shop safety is around ten feet. Five feet is typically too close for many hot surfaces, where radiant heat can reach nearby materials. Distances like fifteen or twenty feet are larger than the minimum and exceed what’s usually required for standard tasks, but since the question asks for the distance closest to a safe value, ten feet is the best choice. If the heat source is especially hot or the materials very flammable, increase the clearance beyond ten feet.