table 300.5 minimum cover

[acrwc10]

we have a situation where a driveway for heavy vehicles runs in one side of a garage and out the other, making this a drive through garage, slab on grade. the trucks will be parked inside until needed. The building is slab on grade, would it be considered "Under a Building" or "under a driveway or parking lot"? For PVC conduit under the slab.

 

[LarryFine]

The former, in my opinion.

 

[rbalex]

we have a situation where a driveway for heavy vehicles runs in one side of a garage and out the other, making this a drive through garage, slab on grade. the trucks will be parked inside until needed. The building is slab on grade, would it be considered "Under a Building" or "under a driveway or parking lot"? For PVC conduit under the slab.

If I were designing it, I would opt for Column 2, if for no other reason than Columns 4 and 6 are very specific, and your application description doesn't cleanly fit either.

While it doesn't specifically say why, NESC Rule 320.A.3 recommends:

Highways and Streets:
When conduit must be installed longitudinally under the roadway, it should be installed in the shoulder or, to the extent practical, within the limits of one lane of traffic.

This is because cables run in underground raceways parallel to one-way traffic, especially heavy loads, can create an interesting phenomenon. The cables will often attempt to physically migrate in the dominant direction of the traffic. For the OP, this may only be a minor effect (the raceways may not actually, "... be installed, longitudinally under the roadway ..." - or it's very short), so I would definitely consult the AHJ - unless I went with Column 2.

 

[acrwc10]

A little more clarification, not residential, not direct burial cable.
I went with “under the building”, it’s a 5” slab and 5”-6” rock, so it has roughly a foot of cover.

 

[infinity]

we have a situation where a driveway for heavy vehicles runs in one side of a garage and out the other, making this a drive through garage, slab on grade. the trucks will be parked inside until needed. The building is slab on grade, would it be considered "Under a Building" or "under a driveway or parking lot"?

Nothing in your description sounds like a driveway, parking lot, or road. At the end of the day it's still a garage.