What is the maximum temperature rise allowed on the nonfire side of a penetration according to T rating?

The correct choice regarding the maximum temperature rise allowed on the nonfire side of a penetration according to the T rating is 325 °F. This rating is part of fire protection standards that detail how firestop systems must perform.

The T rating specifically measures the temperature increase on the nonfire side of a fire-rated assembly when exposed to fire conditions on the fire side. A T rating of 325 °F means that during the fire-test exposure, the temperature on the nonfire side of a penetration cannot exceed this threshold; otherwise, the firestop system is considered inadequate.

Maintaining this temperature limit is critical to ensuring that any barriers designed to prevent the spread of fire remain effective, thus protecting lives and property in the event of a fire. The other temperature rise options exceed the acceptable maximum stipulated in the standards, indicating that if the nonfire side's temperature were to rise above 325 °F, the integrity of the firestop system could be compromised, leading to potential fire hazards.