Which condition would likely require the use of expansion joints in conduits?

The need for expansion joints in conduits primarily arises from thermal expansion and contraction. As temperatures fluctuate, the materials that make up the conduit can expand when heated and contract when cooled. This change in dimensions can lead to stress within the conduit system, potentially causing damage such as cracking or misalignment. Expansion joints are specifically designed to accommodate these movements, allowing for the safe and effective operation of the conduit system across varying temperature conditions.

In situations involving heavy rain, high humidity, or exposure to UV light, while all of these factors can affect conduits, they do not inherently create the same level of dimensional change that necessitates the use of expansion joints. Therefore, the consideration of thermal expansion and contraction is critical when determining when to install these joints in a conduit system, making it the definitive condition that requires their use.