Which fuel system headers have no requirement to connect a grounding cable during servicing?

The correct answer indicates that tank car offloading does not require connecting a grounding cable during servicing. This is primarily due to the fact that tank car offloading operations typically take place in a controlled environment where the physical setup and the materials involved ensure that static electricity and potential sparks are minimized. The significant safety protocols and mechanisms in place during these operations reduce the risk of ignition from static discharge, hence eliminating the need for a grounding cable.

In contrast, truck loading, truck offloading, and tank car loading involve conditions where the risk of static build-up is higher, and therefore, a grounding cable is necessary to prevent potential electrical discharges that could ignite flammable vapors or fuels. These activities happen in environments that may not have the same level of intrinsic safety features as tank car offloading, demanding additional precautionary measures such as grounding to ensure safe operation.

This distinction highlights the importance of understanding the specific practices and risks associated with various fuel system operations to maintain safety standards correctly.