Which metal is used for bonding jumpers when bonding dissimilar metals?

• A. Copper
• B. Aluminum
• C. Zinc
• D. Tin

Answer: (A)

When bonding dissimilar metals, the aim is to create a single, uniform electrical potential and provide a low-impedance path that minimizes galvanic corrosion at metal-to-metal joints. Copper fits this role best because of its excellent electrical conductivity, ductility to form reliable jumpers, and ease of joining to different metals (often with tin plating to further reduce corrosion when aluminum is involved).

Aluminum as a jumper can introduce galvanic issues and is less stable for long, reliable bonds; zinc is highly active and would preferentially corrode, making it unsuitable for a bonding jumper; tin alone lacks the mechanical and conductive characteristics needed for a robust jumper, though copper may be tin-plated to improve corrosion resistance.