California ICC UST Inspector Practice Exam 2026 – Your All-In-One Guide to Exam Success!

An automatic shut-off device is designed to enhance safety during the fueling process by preventing overfilling of underground storage tanks. The correct requirement is that the device must stop the flow into the tank when it is filled to no more than 95% of its capacity. This regulation is crucial because it safeguards against potential spills, which can cause environmental contamination and pose safety hazards. By stopping the flow at this threshold, it allows for the expansion of fuel and provides a buffer to account for any unforeseen circumstances such as changes in temperature that might expand the fuel within the tank.

This regulation ensures that storage capacity is not exceeded, thereby maintaining compliance with environmental laws and industry safety standards. The other options may refer to scenarios that do not align with established safety practices or regulations regarding the filling of underground storage tanks.