PVC Conduit and Steel Enclosures

Yes... as long as you use a female threaded adapter at the end of the PVC raceway then use a metal nipple that screws into the female adapter and goes into your box. Of course, the metal box would have to be approved for the location in which you wish to use it.

This is true under the Canadian code (see CEC rule 12-1112) and I am more than willing to bet under the NEC as well.

Not sure what the rule is there but here you'd also have to ensure each of those metal boxes was properly earthed as well.

The metal boxes will have to be grounded, but the NEC does not prohibit the use of metal boxes with PVC conduit, and threaded PVC connectors will work. Most contractors do not do it since the small PVC boxes take less labor and result in lower cost. Breaker panels are always metal as far as I have seen and frequently have PVC conduit entering them.

I was a technical rep for an agency selling Egatube in the Bristol UK area 50 years ago back in the mid 1960's for a couple of years. It was pioneering work in those days fighting steel-minded apathy and commercial prejudice against the use of plastic conduit.

The limited range of plastic accessories meant you were forced to use metal accessories. Which gave rise to the argument that metal boxes had to be connected using metal conduit because mixing metal and plastic was not permitted. A load of rubbish! -but a popular ploy that seems to persist today - judging by the question.

If that argument failed, you were warned that any saving in labour would be off-set by the cost of extra earth wires - so why bother! All I can say is that those who were not fooled developed techniques in the use of plastic conduit that gave them a distinct competitive advantage.

I am totally out of touch with today's practice but if nothing has changed then mixing metal and plastic is perfectly acceptable - providing rules on earthing/grounding are observed - I guess.

It is OK as long as a ground wire of proper size is provided and used just as you would for all PVC conduit systems. PVC branches originate at metal boxes, such as a circuit breaker box, they can also terminate that way. Just remember though to run the ground with a grounding wire. Good Luck, Old Salt

Thanks for all the inputs.