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  • Andrew T Schwab 9:30 am on April 14, 2014 Permalink | Reply  

    Your Structured Cable Matters More Than You Know 

    Warning! Boring technical post follows. Read at your own risk.

    I recently contracted with two low voltage (ie. data cabling) contractors to do some cable plant improvements at my school district. I had two goals. First, I wanted to beef up our wireless for the upcoming SBAC testing and rather than pull new cable, I opted to back-pull an existing data drop and have it re-terminated in the ceiling for an Access Point. Lets be real here, wired workstations are on the way out and one data cable connected to a wireless Access Point can support 30+ wireless clients versus one wired desktop (mini-switches not withstanding). Back pulling is faster and cheaper than pulling new cable, especially if your existing pathways are full.

    Pro Tip #1 – When building new construction (or modernizing existing), make sure you spec big enough conduit and straight pathways for future data cabling growth. Nothing sucks more than opening a ceiling tile on a newer building and finding the 2″ conduit packed full of cable and realizing there are a dozen 45 degree turns in a run down a straight wing of classrooms.

    My second goal was focused on outfitting two Project Lead The Way (PLTW) classrooms with dual overhead projectors and AppleTVs. Each classroom had two interactive Eno Boards (before my time so I will skip my IWB rant) and the teachers and students were trying to use them with projectors on carts. You can imagine the shadow puppet possibilities.

    A big constraint on this project was time. I wanted to accomplish all this during our spring break. The PLTW classroom project was the trickiest, having to coordinate with Electrical work and Audio/Video installation. The Access Point back pulls were less time critical. For reasons beyond this post, I decided to use two cabling contractors. Contractor#1 I had worked with before and I new to provide quality work. I had them do the PLTW classrooms. Contractor#2 I had not worked with before but they came recommended by our Wireless Access Point manufacturer, so I decided to give them a try and had them back pull and install the APs.

    Pro Tip #2 – The quality of your cabling depends greatly on the onsite project Lead. It doesn’t matter how good a prior reference is, if the project Lead is different from the reference, your experience could be like a box of chocolates.

    I’m not new to structured cabling. I learned how to make and test cat5e cables in college (yes, college) and I’ve designed and managed the complete rewiring of several campuses over the years. I’ve also upgraded cable plants in some seriously old buildings so I’ve seen the good, the bad and the ugly of cabling. In every instance I’m looking for several things that point to quality cabling installation. I know, most people don’t think of cabling as being “installed”. They just see jacks and think they can plug in and go. Not quite.

    Quick signs of a good install for your cable plant:

    • Labels. If the port labels don’t match the wall plate labels, your installer wasn’t paying attention to detail.
    • Proper wall and ceiling penetrations. You should see sleeves (conduit) and preferably you should see some open space in the conduit. Full conduit is a possible sign that the last few cables pulled through it were pulled a bit too hard.
    • Cable bundles are secured and the cables are straight and well dressed. I once saw a brand new install with easily a hundred cables bundled and zip tied together and not a straight cable in the bunch. It looked like someone had tried to tie wrap spaghetti. Your cable runs should look like one big cable, all running parallel to one another. Not spaghetti.
    • Support. Cable runs need to be properly supported. You should see J-hooks, cable trays or conduit supporting your cable as it is run through the buildings.
    • No sharp bends. You should see nice curved radius corners.
    • No zip ties digging into cables.
    • No unsupported cables hanging in the back of the IDF cabinets. Unsupported cables can work lose from the jack and cause issues down the road. Gravity!

    Why does all this matter. Cat5/6 is what they call UTP or Unshielded Twisted Pair. Each cable is made up of 4 pairs. The twist of the pairs in the cable is what prevents signal cross talk and ensures the rated speed and performance of the cable. When you pull on the cable or step on it or bend it, you mess with the twists in the pairs and this can lead to performance issues. Installers have to follow specific guidelines during installation to ensure they don’t damage the cable’s integrity while they are pulling, wrapping and bending the cable through the building. It’s also why quality installers will test every cable they run with a high end tester to ensure it meets performance specs when they are done. So, next time you step on a network patch cable, think about the twists you’re damaging in the process.

    Pro Tip #3 – Write cable testing into your RFP and have them provide a report on all cable testing. You’ll want it for the warranty.

    Back to my tale of two cable installers. Contractor#1 took their time and did things right. They tested every cable and ask when they had questions, suggesting solutions that met my needs and did not necessarily make things easier for them. The lead on the project was very detail oriented and customer focused. They ran into obstacles but never blamed my existing cabling or pathways (although they could have) and got the job done with little supervision from me or my team required. I am confident that when I plug in a device to the ports they ran, they will work (or my device is bad).

    Contractor#2 started off on a Sunday with minimal supervision. By the end of Monday it became clear that we had been sent the C team. Questions were not being asked and the solutions chosen were easy for the installers but did not solve our issues. Some of the issues that came up:

    • Back pulling the shortest cable in the room to avoid having to pop the raceway off and un tape the cable.
    • Mounting APs vertically on the wall instead of horizontally on the surface so they wouldn’t have to get into the soffits.
    • Running cable next to fluorescent light fixtures (never, ever run your cable anywhere near fluorescent lights and always cross power at 90 degrees. Never run parallel to power. Even twists in the pairs can’t protect against that kind of interference)
    • No consistency in AP orientation from site to site.
    • APs not being mounted on T-Bar in drop ceiling rooms because of “weight concerns”.
    • Repeatedly being told our current cable infrastructure was crap, which it may well be but we walked the job, they shouldn’t be using that as an excuse for doing crap work.
    • It went on and on.

    Pro Tip #4 – Be as specific as possible in what you want and how you want things done and then check in on a new lead often to make sure they are doing what you want. Problems caught early can be fixed early and ensure they don’t continue to be repeated. If they won’t listen to you or give you BS reasons why they can’t do it, escalate immediately.

    After some high level intervention and a second crew being dispatched, contractor#2’s lead appeared to be back on tack but I had to dedicate time and resources for oversight every day because I no longer trusted him to do the work the right way. Worse, the schedule was thrown off due to backtracking to sites to fix prior work and my team was distracted from their primary goal of upgrading four sites to VoIP (busy week).

    I spent some time with contractor#2’s Lead on Saturday watching him work. I discovered that the only cable testing he had been doing was plugging in an un-configured Access Point to an un-configured switch. So we know the power pair works but who knows about the data pairs. I guess we’ll see when we go to turn up the APs. I also found out that they had not been redressing the back pulled cables in the IDFs. (we had them terminate the back pulled cables into new patch panels, eliminating potential finger pointing at our old panels when it comes time to light them up). This is something that isn’t visible unless you are looking for it and it left the cables under strain (remember gravity!).

    Bottom line is I now have to task one of my people with checking everything contractor#2 touched so we can generate a punch list for them to come back and fix. I suspect it will be extensive. With contractor#1, I’ll do a spot check here and there but I’m confident we’re good to go. Of course on the first job that Lead did for me I checked everything, but now that I know he does good work, I don’t need to be as concerned.

    Pro Tip #5 – Walk your campuses and look at the cable. You should know pretty quick what condition it is in and where you can expect issues. Address them before you buy new equipment or deploy new network services like VoIP or you will wish you had.

    Why does all this matter? Well, I’ve walked into many situations where cabling is an after thought. Where it is obvious the lowest bidder or Joe Bob and his cousin have wired a school. In those situations, I know there can’t be reliable network service without constant firefighting by the IT department, which is always a losing battle. I’ve seen districts buy brand new networking equipment and plug it into total crap cable plants and expect performance, reliability and stability to improve. Ain’t going to happen. Your cable plant, structured cable, the wires in the wall, are THE MOST IMPORTANT THING in your network. Cable is the foundation upon which all else it built. Don’t skimp on the cable or the contractors and most importantly know what good cable looks like.

    Got any cable horror stories? Id’ love to hear them.


    • Urko Masse 6:34 pm on April 14, 2014 Permalink | Reply

      Great post!
      Lots of small tips to build a checklist for any cabling work that you may need to get done in the future.

  • Andrew T Schwab 8:30 am on April 7, 2014 Permalink | Reply  

    Why 1:1 Isn’t Optional 

    Recently I had the pleasure of listening to a 3rd grade teacher who implemented 1:1 in November talk about how her class and her student’s have been transformed by student access to technology and the Internet in just a few months time. Awesome.


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