At a local factory here, I recently installed 3 x 630mm2 Al conductors in PVC conduit and laid it nicely in fine sand (called crusher dust here), laid a heavy duty warning strip over the top of it at half trench depth, all well and good I thought when it was back-filled. I now find out this morning that the guy excavating a trench for the storm-water drains, dredged up my warning strip and conduit in one fowl swoop, even when told by one of the builders on site there were cables buried in the area where he was digging. Luckily, these cables (singles actually) haven't been livened yet, as they aren't required, as the 2nd stage of the factory hasn't taken place yet and I am still waiting on the switchboard to be fabricated. But, I was supposed to be going on holiday today for 3 weeks, something tells me that won't be happening. I got there this afternoon and all I saw was a big orange curve sticking out of the ground and stripped aluminium cables sticking out of the conduit. Believe me guys, I was nearly in tears, I put a LOT of work into that pull and to see it like that was devastating. What do I do from here though?, do I get the lot dug up and start again?. The conduit (glued PVC) has obviously come apart further down the trench. With the size of conductor involved, I don't feel comfortable with jointing it either, considering it will be carrying something like 400-700A per core. What would you do?.
That's an eerily similar story to a situation that we encountered a few years ago. We were contracted to bury a telephone cable at a new high school that was under construction. The Friday before we started the job (the following Monday), I stopped by to survey the conditions. We only had one potential crossing of existing PVC (4 X 2") containing #4 cables for tennis court lighting. They were newly-installed and about 5' deep in the ground. I mean they were so deep that I got nervous getting close to the edge of their open trench!
Knowing how deep they were, I told my installers to just keep it shallow when crossing that spot. Monday came along, they started trenching at a pretty good pace. When they got to the conduit crossing, the trench had already been backfilled and compacted. They planned to use the trencher just to break the surface of the soil and then dig that part by hand. As soon as the trencher's blade hit the ground, it pulled up all four conduits and broke them. They were now less than one inch in the ground!
The electrical contractor demanded that we pay them for the damage. We refused and were promptly sued. Our argument was that these conduits were not buried at the proper depth per NEC and that even a simple sign or fence post could have easily caused the same damage.
It turns out that we had major heavy rains over the weekend. The general contractor brought in an emergency grading crew on Sunday to deflect the grade & improve runoff. They forgot to tell anyone that this had occurred.
When we went to court, we countersued the GC citing that it was their responsibility to inform the EC that they would need to move their conduits. They had also neglected to tell us about this, even though their superintendent was right there when be damaged the conduits. The EC ended up winning against us, but we ended up winning our countersuit against the general contractor. The judge simply told them to work it out between themselves.