Slightly different scenario for me a couple of years ago. Hospital remodel, parking lot rearranged with new drive for the fuel truck for the pair of choppers kept on the pads. GC had busted out the concrete curb on both the to-be connected drives, and graded, laid out their rebar and mesh. I had the job of installing the sensing loops for the gate system. It's a twisted pair of 18g copper. Usually I just drive pieces of rebar at the corners and stretch it around the rectangle required. It's actually pretty fussy to make it work, and I always worry about the monkeys pouring the concrete disturbing it. This pour started about 4 AM. I find out later that their remesh was arcing to one of my rebar stakes. Guys all in the mud and working it. The lead man just kicked it away so it wasn't arcing. Found out later that several of the parking lot lights were not on. Tripped breaker. It seems I had driven my rebar right through a conduit carrying 208V out to a section of lights. I did my bit during the day, so it wasn't hot. Dark came and the lights went hot. Before I did any of the stake work I specifically asked about anything being under what was just a grassed over area beside the parking lot. Nothing on the original drawings, nothing on the GC drawings. Now under the concrete is a pierced 2" conduit in the dirt with a 3/8" rebar through it. There were spare conductors in it, so once they figured out which circuit was shorted, they simply abandoned that pair and went to a backup. I had the hospital head guy over all construction out there, also a friend of mine, as I was doing the job and mentioned to him that I hoped nothing was there. He said if ts wasn't on the drawings, it better not be. Short story, I never heard another word about it. I think the plant services guys were embarrassed and probably got a little chewing out over not knowing or telling the GC there was hot conduit there. At least I didn't do the digout, and it wasn't so deep that it would have got the conduit anyway, but I changed my tactics a little. I used much shorter pieces of rebar now. The ones I used were longer than they needed to be. It was handy, and they had to be below finish grade....so down they went. I think the GC would have had to eat it, and he may have, but I didn't. Just glad none of the guys in the mud got zapped. Could have killed someone.