The bonding shall be by a clamped, riveted, bolted, or screwed connection; welding, soldering, and brazing materials having a softening or melting point greater than 445°C (833°F). The bonding connection shall penetrate nonconductive coatings, such as paint or vitreous enamel. Except as mentioned in 18.10, bonding around a resilient mount shall not depend on the clamping action of rubber or other nonmetallic material