I've been using thinwall DWV plastic (Sch 30 or even 20) and excepting

for the static electricity annoyance(*) works fine as well.



(*) But it's no worse than the flex plastic, either...

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Read Puckers reply about Bill Pentz idea of aluminum tape. I have it run inside and outside every run and fitting with a complete circuit from one end to the other. You can see it in my pics. I make sure the connecting screws pass through it as well. I connect a copper wire to it at the end with an alligator clip that can be attached to the machine. I haven' had even a hint of a shock, even in the places where the terminus has lost the clip or wire and just having the tape throughout causes enough diffusion it just never builds any static.