Rigid PVC Conduit (Type PVC)

PVC will not corrode, which is why it owns the underground and wet-location market. But it moves a lot with temperature, so long exposed runs need expansion fittings or they will buckle.

Because the pipe is not a conductor, you must pull a separate equipment grounding conductor. I have seen too many PVC jobs where somebody forgot that the plastic will never carry a fault.

When it applies

Rigid PVC is the go-to raceway for underground, wet, and corrosive locations where steel would rust out. It resists chemicals and moisture, but it moves with temperature, so long runs need expansion fittings sized to the expected change. And because the conduit itself is nonconductive, you must run a separate equipment grounding conductor inside it.

Common mistakes

• Omitting expansion joints on long exposed runs, so the conduit bows or pulls apart at the couplings across a hot afternoon.
• Assuming the raceway grounds the system. It does not, so an equipment ground has to be pulled with the circuit.
• Solvent-welding joints dirty or in the cold without letting them cure before the pull.

In the field

On a long south-facing wall I calculate the thermal movement and set the expansion coupling accordingly. Skip that and you will hear the conduit creaking apart within a season.