Working in healthcare has given me a new appreciation for following standards. And that's saying a lot, because I've always been a stickler for following the standards.
We had a facility cabled recently where the installers didn't follow the industry standards and didn't follow our specifications. They used electrical staples to secure cables in the attic, had too much jacket stripped off at the terminations, too much wire untwisted, etc. Some of these runs actually certified, but there were lots of dropped packets and the computer would frequently drop off the network altogether. Sure, you had a link light at either end, but there's a hell of a lot more to it than that. The installers were sent back out to re-terminate, remove zap straps and staples, and certify. While you cannot undo physical damage to a cable, the difference was noticeable. Not a big difference in the test results, but from a practical standpoint, the computer stays connected to the network and the transmission errors have dropped way down.
At one of the hospitals there was a cable that we suspect was damaged during some unrelated construction work. The cable had a marginal pass with the certification meter, with return loss being the worst offender. That's a good sign the cable was probably crushed or kinked somewhere in the ceiling. The reflections were causing collision errors which a normal workstation was able to deal with reasonable well. Unfortunately this drop was used for a diagnostic imaging workstation, and the software was very sensitive to latency and transmission errors. Almost every time the software tried to communicate with its server it would time-out.
My point here is that just because something appears to work when you do something like splitting a 4 pair cable for voice and data, or running data over a 3pr Cat3, it doesn't mean it's working very well and it certainly won't work in all situations. It's like using the "boot" many cars have as spare tires. Sure you can get from point A to B, and you can probably get away with driving faster than the rated speed. Nobody here would want to drive on that boot any longer than absolutely necessary. You wouldn't let a tire shop to put 4 of those on your car and tell you it's good enough.
If you're doing something as a professional, you do it in a profession manner. I split a cable for two computers in my house, so yes, I'm very much aware that it is possible. I would NEVER do this for a customer, and I would never let a contractor get away with doing this in one of my facilities. It either gets done properly, or it doesn't get done at all. Even a house built in the 80's can be cabled properly. It just takes the right expertise, tools, time, and materials. If someone isn't willing to pay for the work or the don't want to see any raceway, then perhaps they should stick with wireless.
