PVC conduit with 3/4-inch and 1/2-inch diameters is most commonly used in residential applications. A length of 10 to 20 feet is usually sufficient for any household electrical work. Shorter segments of 3/8-inch gauge flexible styles are usually used to connect motors and machinery where rigid lines are impractical.
Larger diameters allow more wires to be run through one conduit. Industrial and underground installations can call for steel or PVC lines with diameters of 3, 4 or even 6-inches to accommodate all the cables that must be run. These jobs can require 500 feet or longer conduit lengths.Learn more about Electricity