Vehicles carrying inflammable materials usually have metallic ropes touching the ground during motion in order to

Vehicles carrying inflammable materials, such as fuel tankers, accumulate static electricity during motion. This buildup occurs due to friction between the liquid cargo and the tank walls, as well as friction between the vehicle's tires and the road surface [t1, t3]. Since inflammable materials are highly sensitive to sparks, any sudden electrostatic discharge (ESD) could ignite vapors and cause an explosion [t3, t5]. Metallic ropes or chains are attached to the vehicle's chassis and allowed to touch the ground to provide a continuous conductive path [t3, t4]. This process, known as grounding or earthing, ensures that the static charge produced by friction is immediately conducted to the earth, which acts as a vast reservoir that neutralizes the charge [t1, t4]. This prevents the accumulation of dangerous voltage levels and mitigates the risk of fire during transit or loading [t1, t7].