I ran into this situation a couple of years ago.
I got a ticket for "PC won't communicate with network" in one of my stores. I go in and perform the usual checks–continuity only–on the drop and patch cables, check the switch port, the whole nine yards. Everything checks good, but the PC won't connect reliably from that drop. I'm thinking I have a bad NIC, so I take the PC to another drop, hook it up, and it works fine. Take the PC back to its original location, it works. WTF? Then it goes down again.
I keep checking stuff, then decide I'm going to tone the line out, mostly because I'm stuck on what else to do. I plug the toner in one end and go back to listen at the other. Sounds great...no, wait, what the h3ll is that noise?
Up into the ceiling to trace the line and see if I can find out what the problem is. I locate the UTP at the top of the wall, and give it a tug to see where it goes. It's almost guitar-string tight. I break out the floodlight and follow the cable back across the ceiling tiles to the walk-in cooler, where the cable is stretched tight across the top of the condenser motor! Every time the condenser starts, down goes the link.
Check behind the wall plate for the drop, looking for a service loop, nothing. Check upstairs, nothing. It's bow-string taut even up there. I spent the next hour up and down the ladder, tracing that cable and looking all over for anything resembling a service loop. There isn't one; that cable is taut from end to end. We wound up telling the customer they would have to have a new drop pulled.
Don't know who pulled it, but hopefully that id10t is not still pulling cable. I don't mind him laying it across the motor, but to not leave a service loop in case of problems?
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