Which material should be used for bonding jumpers between dissimilar metals?

• A. Aluminum
• B. Copper
• C. Steel
• D. Nickel

Answer: (B)

When bonding jumpers between dissimilar metals, you want a conductor that provides a reliable, low-resistance path and resists corrosion in mixed-metal joints. Copper fits this role best because it has excellent electrical conductivity, is easy to form into jumpers, and can be readily plated or coated to protect joints with other metals. This keeps voltage drop low and connections durable, even when the jumper touches different metals like aluminum or steel.

Aluminum, while lighter, doesn’t conduct as well as copper and is more prone to forming insulating surface oxides and galvanic interactions with other metals unless heavily treated. Steel has lower conductivity and is more susceptible to corrosion, making it a poorer choice for a bonding jumper. Nickel offers good corrosion resistance but has higher resistivity and cost than copper, making it less ideal for a jumper.

So, copper is the best choice for bonding jumpers between dissimilar metals.