Tires are good enough conductors to allow electrical charge to escape to ground. Keeping the dispenser nozzle in contact with the container at the inlet or with the fuel tank fill tube creates another path by which electrical charge can escape. This is because the dispenser is grounded and the nozzle is bonded to the dispenser through the dispenser hose. When a vehicle or other equipment can't be placed on the ground, a second defense is to fuel more slowly. The slower gasoline flows, the less static electricity is generated.
People usually pour fuel more slowly from a portable container than it is delivered by a dispenser.
Keep nozzle in contact with the container while filling. Do not use a nozzle lock-open device. It is unlawful and dangerous to dispense gasoline into unapproved or improperly labeled containers. Other Safety Information about Containers Approved Containers. Federal, state, and local regulations make it unlawful to dispense gasoline into unapproved or improperly labeled containers.