Its fall and time for a little house-cleaning at work, so I decided to tackle the long-standing issue of old, unused cables left behind from older control systems in our lecture halls. There are several cables, including some RG-59 coax, and a few pieces of 24-conductor twisted pair, all stuffed into a 2" pipe. The pipe goes into the floor, straight down, takes a sharp turn, runs under the floor, and pops back up through the floor in another room. The run is maybe 100 feet, and since we’re on the ground floor, the pipe is embedded in concrete. To the best of anyones knowledge, there are no junction boxes, its just a continuous piece of pipe. The cables in it have been there for at least 30 years, maybe longer.
The first order of business is to pull like hell. I try this a few times, with no luck. Clearly something stronger is called for. Real electricians use something called a ‘cable puller,’ also known as a ‘tugger’. Now I don’t have one of these, but I do have access to any number of devices for amplifying human effort. After considering, and abandoning, a number of ideas (including using a come-along mounted on a sawhorse) I settle on a simple 2-ton engine crane. I wheel the crane over the pipe, lower it, tie a piece of coax onto the hook, and start pumping. The crane boom rises; tension on the cable increases. Pumping the hydraulics gets harder. Soon the boom starts to flex a bit. I keep pumping, and suddenly the system goes slack. But it turns out I HAVEN’T pulled the cable part way out of the pipe. Rather, the coax has simply snapped under the force: insulation, braid, conductor, dielectric and all.
So my question to the assembled minds of the Dope is: what the hell do I do now? I mean, if the amount of force required to SNAP the cable isn’t enough to dislodge it from the pipe, what else can I try? It SHOULDN’T be in there this tightly; I can only imagine that over the last 30 years the insulation on the cables have degraded to the point where they are welded in place. Is there anything that can be done to loosen them up? I could try pulling on the twisted-pair, its probably stronger than the coax. I’m hoping that if I can get one cable free, the others will come out more easily.