Archive for July, 2014

Cabling and De-cabling

The school I work at is 57 years old this year. This means that over the course of the life of the school buildings, lots and lots of cables have been installed for various systems. Discounting electrical cable, there are cables for the computer network, the burglar alarm system, the classroom and corridor intercom system, the old analogue and later PABX phone systems and even some analogue CCTV cables laying around somewhere in the roof.

After a recent venue reshuffle, my colleague and I have had the fairly rare chance to really go wild and rip out as much of the useless cable as we can find in the areas that were reshuffled. We decided not to just cut off the cable at the most convenient spot, but to follow it as much as is practically possible all the way back to its source. This method takes a lot more time but is a much more thorough cleansing than if we just snipped when it vanished from view.

As we’ve followed the cables and opened trunking, it’s become abundantly clear that cable was never ever removed in the past. The phone system in particular is an example. From what I can figure out and from talking to long time members of staff, it appears we once had an analogue phone system from our national phone company. There were no internal extensions, only direct lines all over the show. This meant that the phone company ran a lot of thick multi core cabling all over the show before using one or two pairs for the end jacks. We’ve discovered that many of these thick multi core cables simply taper off to a dead end point.

When the school got a Samsung analogue/digital PABX, the telecoms company that installed it simply ran their floor cables all over the show without removing the older cables first. Hundreds of meters of cable were run to support the Samsung PABX. Often cables were glued on the walls, in door frames or wherever else, often leading to a very messy appearance.

Two years ago, we moved to an Avaya VoIP system, which runs on the existing network cables. Although the telecoms company responsible for that system did rip out quite a bit, they didn’t bother going after the floor cables or anything like that. So for the last 2 years, we’ve been sitting with a lot of dead cable all over the show. When we eventually get to ripping it out, you end up with a pile like this:


That whole pile is either multi core cable from the original phone system, or from the Samsung PABX. We had about 2 other piles of similar size when we cleaned up other venues, though those did include network cables and some power cable as well.

With the removal of so much cable, it becomes possible to install smaller and more compact trunking which not only looks neater, it also leads to easier cable management. Getting cables to stay in place while you hammer the cover back on of a 100mmx40mm piece of trunking is not an easy feat.

When I head back to work after my break, we’ll no doubt continue the hunt for cables and rip out as much of the dead stuff as we can find. I just wish it was easier to recycle these cables than it currently is.

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