In which order should aluminum and copper be placed when making connections?

When making connections between aluminum and copper, placing aluminum over copper is important due to the properties of these two metals. Aluminum has a higher tendency to expand and contract with temperature changes compared to copper. This placement helps ensure that the aluminum does not create a pressure point on the copper, reducing the risk of connections loosening over time due to thermal cycling.

Additionally, the connection must be designed to mitigate corrosion, particularly galvanic corrosion that can occur when dissimilar metals are in contact. By positioning aluminum over copper, you help ensure that the connection is not compromised by electrical and thermal expansion, thereby promoting a more stable and durable joint. This consideration is vital for maintaining the safety and reliability of electrical systems, especially in high-current applications typically encountered by linemen.