The lack of properly installed expansion fittings can take a tremendous toll on PVC conduit runs. Why? Because of the effect that thermal expansion and contraction can have on the installation. PVC bodies can be cracked, sag, warp or even break into pieces if expansion fittings are not installed.
The resulting damage can cause conductors to be exposed to sunlight, ice, snow and rain. Interestingly the potential damage is not limited to exterior locations. Interior locations like attics, lofts, barns, sheds or garages can experience seasonal temperature swings that can jeopardize installations as well.
Thermal expansion questions are frequently included on electrical examinations. How would you answer the following question?
Question:
400 feet of PVC conduit is installed above grade outdoors. The warmest temperature the conduit will be exposed to is 120 degrees F. The coldest temperature is -20 degrees F. What will be the expansion of the length of the conduit in inches per 100 feet?
A. 5.07 inches
B. 5.27 inches
C. 5.48 inches
D. 5.68 inches