Can plastic conduit be used in place of metal in normal above ground housing wiring?

I am installinga hot tub. Can plastic conduit be used in place of metal in such a project?

Depends on the situation, setting, amount of possible physical damage... and most importantly your location and local code requirements.

A reply with a few details would help us help you.

Codes permitting... probably. One thing to consider is PVC doesn't offer a ground... a ground wire will need to be pulled along with the circuit conductors.