All construction materials expand and contract with fluctuations in temperature. These temperature changes affect PVC more than traditional materials such as aluminum and steel. For example, the coefficient of thermal expansion for PVC (3.38 x 10-5 in./in./°F) is almost three times as high as for aluminum and six times as high as for steel. Thermal expansion and contraction have a significant effect on long straight runs of conduit. For this application, expansion fittings are used to accommodate changes in length. This prevents potentially harmful thermal stresses in the conduit itself or in any supporting structures. Not only does this help prevent sagging conduit, according to the Canadian Electrical Code (CEC), if the amount of expansion expected due to temperature variance during and after construction is more than 45mm, expansion joints must be used.
- Prevent stress from thermal expansion
- Keep your conduit run up to code