Hello Mike, are you about to rip some good ole pvc?

Ok, let me clarify a couple of things. First off, this is a long jig for holding the PVC so it does NOT rotate as you rip. THATS ALL. If you are ripping 200 pieces, like we did at work, this may not be worth the trouble for one piece. Especially if you have diameters where you can cut the whole diameter in one pass on a tablesaw. Make sense? It was only a tip, to show how to cut it STRAIGHT, with no roll. But you cut the jig as well. Once the jig is cut at the tangent point, that piece of support wood is no longer there, but still will support it if you have the side of the PVC tube, clamped to the vertical portion of the jig. Make sense?
USUALLY, we would use "flip lock" clamps, but you could use a couple of small "C" clamps, or just a screw, one at each end of the tube. But MAKE SURE THE CLAMPS WILL CLEAR THE BLADE. Again, depends on the diameter of the tube. Clamp, or screw, right where the PVC touch's the vertical portion of the jig(tangent point). However, the radius of the tubing was USUALLY higher than the fence, which allowed the clamps to clear it when feeding the assmbly through the blade. Otherwise, you have to clamp a piece of flat lumber to the saw to act as a fence, when cutting small diameter stuff. Remember, we were cutting a shitload of this stuff. Or cutting specific ARCS out of it. AND, remember the saw kerf removes an 1/8" of material, so if you needed EXACT halves, like we did sometimes, you waste the other half. Otherwise you only loose a 1/16" each side of the centerline. To do one piece, well I probably should have kept my mouth shut and agreed with STEVE. But you know me. Bla bla bla.

I just HAVE to open my big mouth. Ha! But, it's still a tip no less. My disclaimer was QUALITY of cut.
One other thing too. When you cut small diameter stuff, it looses much of its stiffness. Even 3"
What diameter and length are you dealing with? I've done up to 14" diam, 16 long' with a 3/8" wall. I've also done as small as 1"diam. Large diameters require extra measures. But your probably dealing with 3 or 4", correct. I can't imagine going to this trouble to make a trough only 1 1/2" or thereabouts. But just so I don't bla bla about something that your not even doing, tell me, ok?
I mean, I assume you are ripping the pvc....right? But tell me exactly what your dealing with.
I'll be back if need be. Oh, speaking of tired, oh yea, me too. "Honey do's will wear ya out" Mine was building a fireplace mantle/surround today. Funny how you can spin yer wheels all day and be so tired at the end of it, and not accomplish a damn thing.

Anyway, get back to me and we'll pin it down.
As far as the "L",imagine a ripping jig, the length of a PVC tube. Cut 2 pcs of some material like 1/2" ply, or OSB about a half inch wider than the diameter of the PVC. Nail or screw one piece to the other along one edge to form an "L" , same as "angle iron" or an aluminum extrusion. Now, lay the tubing on the jig right up tight at the inside corner, where both pieces of the jig are touching the "tangents" of the PVC. Does that make sense? Most of the PVC tubing is 10', but the ply is only 8'. So you may end up having to use boards instead if you need it longer than 8'. Also, most of the PVC I worked with came warped. Makes it difficult sometimes. Hence the jig. We would lay the tubing with the "crown" of the warp up against the jig, and pull the ends back and clamp them. No one said this stuff would be easy. Sometimes it is. But try and straighten 12 or 14" warped stuff, and its a real pain in the ass. Soooooo, maybe refer to Steves answer. But then it may roll. Depends on how straight you want it, dig?
But as an aside, exactly why do you want to use a trough? Most of my cableing tiedowns are done with a long piece or pieces of 1/2" metal electrical conduit on standoffs and conduit clamps. I just tie off the cables to it with velcro or cable ties. NO TROUGHS. Except in the floor, and they will be wood floor cavities. But you would have to see my console assembly to understand it.
BTW, see my link to Doug Moffits website? They make a hanging cable/wire management bracket that works pretty good. Like a big plastic "j" hook, from extruded PVC, and cut into 2" wide pieces. You just fasten them to what ever. A desk, fixture, console, wall..you know.
And if the 120v thing threw ya, sorry, I was referring to frederics response on another thread. To him, 120v stuff was small change. I was making an analogy. A bad one.
Whew!, man, I should have bit my tongue.