Re: subfeeds
Installing PVC underground and protecting it from physical damage is a "judgement" call. If the inspector thinks the installation needs protection from physical damage, then he can request schedule 80. I would always call ahead for the "judgement" call. I have seen where some require sand in the trench and then allow schedule 40.
300.5(F) is where they will "hang their hat".
When I inspect a trench, it is easy to see if the backfill contains a lot of rock. If so, then I ask for the contractor to remove the larger rocks, and fill or fill first with some soil or sand then backfill. I have not seen this as a problem in our area, as most contractors have been doing this since before I became an inspector.
"300.5
(F) Backfill. Backfill that contains large rocks, paving materials, cinders, large or sharply angular substances, or corrosive material shall not be placed in an excavation where materials may damage raceways, cables, or other substructures or prevent adequate compaction of fill or contribute to corrosion of raceways, cables, or other substructures.
Where necessary to prevent physical damage to the
raceway or cable, protection shall be provided in the form of granular or selected material, suitable running boards, suitable sleeves, or other approved means."
