dusty wrote:What characteristics of glued plastic conduit make it safer than properly installed metal conduit? Just a question
I readily agree the poorly installed metal conduit is a hazard waiting to happen.
I have more faith in the pvc cement than the compression fittings, and extremely more so than the single screw type. The glue process can be screwed up, but does not involve metal edges and is more apparent.
Think of the plastic conduit the same way as double insulating. The historical safety using grounding connector on the appliance depended on the continuity to ground. Double insulated appliances only rely on the extra layer of 'insulation'.
You run a grounding conductor to satisfy the need of those historical 3 wire appliances. For double insulated appliances the grounding wire is redundant.
Back when EMT was 'evolving' the crush resistance was a concern.(one does not easily 'crush' rigid metal pipe) I have not 'tried' but suspect EMT crushes more easily than pvc. After all EMT
is bendable! One does not bend pvc(without much heat).
So if durability is the desired attribute, use RMC(if you can afford to
):D.
Anyone use Cast Iron water pipe any more? Same for RMC(essentially the same stuff).
A picture that frequently comes to mind when thinking about pipes etc. is one of a local hotel that was being demolished. The pix included several stories of exposed drain pipe with the bath tubs still attached and supported
only by the plumbing. They were CI tubs! Consider that those joints in the
stack were leaded.