PVC conduit is most commonly used in underground applications, often between the utility transformer and the electrical meter on a property. A lot of times PVC is run through and stubbed up through concrete slabs into locations where walls will later be built.
There is a difference between PVC Pipe and PVC Conduit. Plumbers use pipe, and fill it with pressurized water. The pipe is tested for pressurization, whereas electrical PVC conduit is not tested for pressure or leaks. The intent of PVC conduit is not to hold pressure in, it’s to allow the conductors a safe raceway to live in that minimizes exposure to damage and degradation.
PVC conduit uses glue to hold the ends of adjacent pieces and fittings together. Once set the glue makes it extremely difficult to get two pieces of PVC conduit apart. Especially where primer is used. The benefit of using primer on PVC conduit, before applying glue, is that the primer allows for a reaction to take place which melts the two pieces of PVC together. Creating, essentially a weld. Wheras not using primer, simply sticks one piece to the other. Either way is fine, there are no code stipulations on the use of primer with PVC conduit, however the intent of using PVC is to limit moisture to the conductors as much as possible – especially when using conductors who’s insulation is not rated for exposure to high levels of moisture.
PVC conduit has similar fittings to all of the other types of conduits (couplings, male and female adaptors, and elbows) however there is an added accessory called an “expansion joint” that is used to help the conduit automatically adjust to wide changes in temperature. PVC conduit is quite flexible when introduced to heat, and if installed on a wall in Texas, it will start to bend and sag over time. Expansion joints aid the conduit in being able to flex in this situation.