> dark grey PVC-like conduit (is it actually PVC? I have no idea)
It is.
> I've seen electricians run the same stuff and I knew the glue they use was clear
The solvent ("glue") is more typically grey than clear IME for PVC electrical conduit. For PVC electrical conduit, it's a one-step process (no primer needed).
For PVC water or DWV pipe, it's a two-step (primer and solvent-glue) process; it's the primer that is typically colored and the solvent typically clear. The color in the primer is to facilitate inspection afterwards and the pipes are typically hidden. Electrical conduit is often visible where installed, and there's less tolerance to have the staining from the primer step used in water piping.
That's somewhat incorrect. 90% of PVC pipe is buried in the ground because it can't be in an exposed area "subject to physical damage" which basically limits you to underground or in the ceiling (usually interpreted as over 8 feet above the finished grade). In addition, the NEC requires PVC to be supported every 3 feet whereas EMT only requires support every 10 feet. You'll also see a lot of bending PVC with heat boxes (which often leaves dark patches). As an added bonus, PVC sun rots. PVC pipe and boxes (esp schedule 40) become extremely fragile after a few years in the sun (you can break it by accidentally bumping it).
Running PVC looks unprofessional. It's generally true that if an electrical installation looks good, it is good. If you're running PVC everywhere above ground rather than EMT, you'll be in for a very difficult time when the inspectors arrive.
The glue is not for water-proofing (it's to keep the pipe from breaking apart -- esp during wire pulls). If it's underground, you'll be using THWN (waterproof), so the water doesn't matter. For that reason, no primer is needed. The reason for "electrical glue" is that it's much lower quality and much cheaper (you'll see contractors use whichever glue is cheapest regardless of color).
> [PVC rigid conduit] can't be in an exposed area "subject to physical damage" which basically limits you to underground or in the ceiling (usually interpreted as over 8 feet above the finished grade).
NEC citation for that, please? I see it used outside all the time, including in utility service entrance usage (which I cite because I suspect is overwhelmingly likely to be inspected) and many landscaping applications where it doesn't corrode like EMT. I believe it is suitable for use in such locations where the conduit is identified for that use.
Completely agree that buried PVC is a wet location; that's clear from code and I never argued otherwise nor argued that PVC solvent was for water-tightness in electrical application.
I looked it up (I read the code a lot when working in that field, but that was well over a decade ago now). Physical damage is in 352.10 (F) and 352.20 (C). Support distance is in 352.30.
To be more complete, Schedule 80 is permitted in areas subject to physical damage, but not schedule 40 (much more common). Likewise the AHJ (authority having jurisdiction) has ultimate say. In the area I worked (and in most jurisdictions from what I was told), you had better have a very good reason for exposed PVC outside of service entrances or similar.
EDIT: for sake of thoroughness, At a service entrance, you have overhead and underground. Overhead will be using RMC (rigid metallic conduit) to the meter. You can usually get permission to use PVC from the meter to the outside shutoff (required for non back-to-back panel installations) and can usually run a couple feet of PVC from there to turn under the house. I saw someone run an outside exposed PVC from the panel to the HVAC and it got called immediately (bury, put in the wall, or switch to EMT). With trailer installs, I've seen them permit a jump from the pole to the trailer above ground if a box was built around the PVC at the crossing.
It's worth remembering that the NEC is both a minimum requirement and a suggestion at the same time. The AHJ is given a lot of leeway because the minimum requirement doesn't fit every situation. Likewise, loads of districts use outdated versions of the code (that may not sound big, but things like AFCI (arc fault breakers) in bedrooms still isn't required in a lot of districts because they are on the 199x or early 200x code).
Section 352.12(C) prohibits PVC for installations where
“subject to physical damage” unless identified for such use.
However, the meaning of "subject to physical damage" is supposedly a little loose, and most documents/training I've seen calls a typical vertical outdoor electrical service entry allowed.
You can get clear primer for water PVC. If the inspector trusts you he will let you use it. However if the inspector has any doubts about your abilities he will demand you use the purple stuff (including rip out all your work that is probably perfectly good just so e can see you used the primer). The purple is just a dye, it serves no purpose other than to inform the inspector that you used it.
The reason you don't need primer on electrical is the connection is only required to be mechanically strong - water leaks are just fine. If there is any possibility of water getting into pipe you are required to use wires that have a waterproof insulation.
It is.
> I've seen electricians run the same stuff and I knew the glue they use was clear
The solvent ("glue") is more typically grey than clear IME for PVC electrical conduit. For PVC electrical conduit, it's a one-step process (no primer needed).
For PVC water or DWV pipe, it's a two-step (primer and solvent-glue) process; it's the primer that is typically colored and the solvent typically clear. The color in the primer is to facilitate inspection afterwards and the pipes are typically hidden. Electrical conduit is often visible where installed, and there's less tolerance to have the staining from the primer step used in water piping.