What size conduit under deck??

[lelandtampa]

I ran 3" really thin wall white PVC. I was able to stomp it down into the chases in the big box stringers on my 78 MA. I think it's sch. 20 drain pipe.

[wattaway2]

The white schedule 20 pvc can be heated and belt BUT it collapses VERY easily!
It will get you more room inside do to the thinner wall thickness (OD is the same as sch.40) I’ve heard you can fill it with sand to keep it from collapsing but then the sand holds the heat Or you can seal both ends of the pipe so that the heated air inside expands to keep the pipe from collapsing .If you look at an electrical 90 degree bend and compare it to a plumping fitting you can see a major difference. The larger radius is to allow wires to be pulled much easier