Movable metal items may be connected to earth via the bonding bar using the type of clamps and cables illustrated. The clamp should be designed to grip the container securely and to bite through any paint or rust layers. As a mechanical device, it should be approved for use in the appropriate Potentially Explosive Atmosphere zone. Cable cores and connections should be strong enough to avoid damage from repeated movement as the clamp is brought to and from the container.
CLC/TR 50404 states that: There are items of equipment such as drums, funnels and trolleys, which cannot be permanently connected to earth through the main plant structure ....... To allow for this suitable temporary earthing connections should be used (11.3.1.2).