Structural Strength

• Plumbing PVC relies on the water contained within it for its structural strength. It must be secured to the side of a building or firmly attached to beams or studs in order to prevent snapping under its weight. It is designed to withstand high internal pressure, typically at least 120 PSI, but is not known for its structural strength.
  
  

Ultraviolet Resistance

• Electrical conduit PVC is designed to be UV resistant. This means it can be exposed to the elements outdoors and not degenerate significantly. This is important in applications, such as outer wall electrical conduit, where water-tightness and tensile strength, after prolonged exposure to sunlight, are a necessity. Plumbing PVC will crack and split when left outdoors in full sunlight for a prolonged period of time.
  
  

Connections

• PVC conduit is typically flared at one end to form a female coupling point. PVC cement can be used with PVC conduit, but it can also be simply fitted together, with gravity holding everything in place, when the application is vertical. Plumbing PVC must be cemented together, and the ends are not flared. Couplers are separate pieces that are added onto plumbing PVC pipe to form joints.
  
  

Pressure Ratings

• PVC conduit typically has significantly lower pressure ratings than plumbing PVC. PVC conduit is intended for cables and wires, not high pressure water or air. As such, PVC conduit should never be used for any application where it will be exposed to high pressures. Cracking, splitting and bursting are very real possibilities and can be dangerous. As well, plumbing PVC should never be exposed to pressures exceeding those that it is rated for.