Without expansion joints what issue can occur at busbar connections?

• A. Without expansion joints there could be excessive movement on busbar connections which can cause them to loosen and have high resistance
• B. Expansion joints are purely cosmetic
• C. Busbars become waterlogged
• D. Current capacity decreases without joints

Answer: (A)

The main concept here is that metal connections in busbar assemblies must tolerate thermal and mechanical movement. When current flows, temperatures rise and parts expand; as they cool, they contract. If there are no expansion joints to absorb this movement, the stress concentrates at the busbar connections. Over time, that can cause the connections to loosen. A loose connection raises contact resistance, which generates more heat and can lead to further loosening, arcing, or failure.

So the best answer emphasizes that without expansion joints, excessive movement at the connections can loosen them and create high resistance. Expansion joints aren’t cosmetic, busbars aren’t made waterlogged by the absence of joints, and while poor contact from a loose connection can affect performance, the direct issue described here is the mechanical loosening and the resulting increase in resistance.