A fire extinguisher, rated not less than _____________ shall be provided within 50 ft. of wherever more than 5 gallons of flammable or combustible liquids are being used on the jobsite.

The requirement for providing a fire extinguisher rated not less than 10B within 50 feet of where more than 5 gallons of flammable or combustible liquids are being used is based on fire safety regulations that aim to ensure adequate fire protection in environments where flammable materials are present.

A 10B-rated extinguisher is specifically designed to handle fires involving flammable liquids such as gasoline, oil, and solvents. The numeric rating corresponds to the square footage of the fire the extinguisher can effectively manage, indicating that it is suitable for combating larger fires that could arise from ignited flammable liquids.

In contrast, lower ratings like 5A or 15C do not offer the level of protection required for significant quantities of flammable or combustible liquids. Ratings like these would likely be inadequate in addressing the potential hazards associated with a larger fuel load, hence the necessity for a 10B rating in such scenarios. The choice to require this specific rating underscores the importance of selecting equipment that can effectively mitigate risks associated with fire hazards in the workplace.