Can I use Schedule 40 PVC to protect a 4 AWG grounding electrode conductor (wire from main panel to grounding electrode) where exposed to physical damage (a few feet between the panel and the ground rods)?
Per the section 250.64 of the 2014 NEC, it looks like I can use schedule 40 because it lists "rigid polyvinyl chloride conduit (PVC)" without specifying the schedule. In other sections of code, it is usually very specific about the use schedule 80 where wire is exposed to physical damage. Also, the inclusion of "cable armor" in section 250.64 as a means of protection from physical damage is a possible indicator that this section of code is relaxed since I otherwise understood cable armor to be prohibited for use where protection from physical damage is required (see heading "Question #3" in this answer).
Ideally, I would use EMT since I am most used to working with it when I need conduit or a raceway, however the additional requirements to bond metallic raceways at their termination for a grounding electrode conductor adds additional hassle/fittings that I would rather not deal with. Therefore, I am looking at the non-metallic conduit options and I am having a tougher time finding schedule 80 PVC in sizes less than 1 1/4" at local stores while schedule 40 PVC is plentiful in a variety of sizes.
Below Quotation is from NFPA-70:2014; The 2014 National Electrical Code
250.64 Grounding Electrode Conductor Installation.
(B) Securing and Protection Against Physical Damage. Where exposed, a grounding electrode conductor or its enclosure shall be securely fastened to the surface on which it is carried. Grounding electrode conductors shall be permitted to be installed on or through framing members. A 4 AWG or larger copper or aluminum grounding electrode conductor shall be protected if exposed to physical damage. A 6 AWG grounding electrode conductor that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection if it is securely fastened to the construction; otherwise, it shall be protected in rigid metal conduit RMC, intermediate metal conduit (IMC), rigid polyvinyl chloride conduit (PVC), reinforced thermosetting resin conduit (RTRC), electrical metallic tubing EMT, or cable armor. Grounding electrode conductors smaller than 6 AWG shall be protected in (RMC), IMC, PVC, RTRC, (EMT), or cable armor. Grounding electrode conductors and grounding electrode bonding jumpers shall not be required to comply with 300.5.