Learning By Doing

I realized as I started to follow up on my previous post about selecting a cable for use in a temporary data logger field deployment with the DC power supply panel that before I could talk about why I might have selected a certain cable, I probably need to talk about about the general construction characteristics of the cables I was looking at.My own knowledge about building wiring practices started to evolve in the late 1970’s as I became involved with the installation of computer based control systems and it has grown in spurts since then. My most recent learning experience was related to my decision to install a structured wiring system in my house, partly to organize the growing preponderance of wiring that is becoming “standard” in the modern home, (especially the modern home with office) and partly because I like building things and learn a lot by doing.

Here is a picture of the heart of my little home structured wiring system, which will likely give some of you a chuckle if you are professionals (or maybe even if you aren’t).

Structured wire 10

For those who are wondering what you are looking at, the left side is mostly the Ethernet stuff, starting with a patch panel at the top, where the various cables that run out to jacks in the house come into the panel. Below that is a power over wireless adapter that supports my wireless interface point. The black box below that is my router with the cable modem that hooks me up with Comcast below it. The black mass of stuff sitting in the bottom of the panel is just bundled up power cords, and a power supply along with a surge protected power outlet mounted on the bottom of the panel.

The right side has the distribution panel for the cable that coming in from Comcast and going out to our televisions and the cable modem. Below that is the punch-down block where the phone lines come in from QWest and then distribute to the extension locations in the house. At the bottom on the right side are terminal strips that distribute the output from my receiver (both speakers and a zone output) to my office and speakers on our back deck. The zone feature on my receiver is pretty cool and something that I had not paid much attention to, but its really nice. In general terms, it provides a separate, low level output for two zones that are independent of the primary output. To use it, you have to run it through a separate amp, but once you get it set up, the receiver can support two different functions at the same time.  You can even get a wireless remote (which I don’t have) (yet) that lets you control the receiver from the remote location.

The hardware is from a company called OnQ Legrand, a product line I ran into at the local Lowes store.  It has worked very well for me with good documentation (always appreciated by a commissioning practitioner) a nice web site and a knowledgeable and responsive technical support staff.  You can find similar stuff on the SmartHome website and others like it.

I also found a number of good books on the topic including Lan Wiring by James TruLove, that I picked up used at Powells Technical Books a while back for a couple of bucks and a fairly comprehensive, residential wiring oriented guide called Home Cabling Guide that you can download off the internet for about $15.  There also are websites dedicated to the topic.  I found the Structured Home Wiring site to be useful on several occasions.

The bottom lines are that there is a wealth of information out there if you want to try your hand at a project like this.  And, in may case at least, the system seems to work and I sure had fun putting it together and learned a lot by doing it. Before my adventure:

I’d seen but never really understood a punch down block or how they work. It turns out that they are a really fast way to land wires, but there are a lot of details (and a few special tools, darn the luck) required to do it right. And, if you try to cheat, things may not work very well.

I had a fundamental grasp of why you might use twisted pair wiring, but didn’t realize how critical the twists are in terms of the performance of a 100 Mbps Ethernet cable. For instance, if you use cable ties and pull them too tight or use standard cable staples like you might use to run “Romex”, or make nice sharp bends in the cable to turn a corner, you will probably distort the twists which can (I proved it) (unintentionally) severely limit the performance of your cable. Untwisting the wire for a couple of inches to land it has the same effect. Smooth turns, plastic staples shaped to loosely support the cable when driven fully home, and gently snugged up velcro cable ties are much better ways to go.

Kathy and I both enjoyed the music from our “obsolete” receiver but had not really explored some of the features included in it until I looked into running speaker wires down to my office. That’s when I discovered the Multisource feature and now, Kathy can be listening to the CD player and practicing her singing upstairs while I have All Things Considered playing in my office downstairs as I finish up work for the day. Since this is an “obsolete” electronics package, I suspect there are a bunch of even cooler things that you could do if you happen to be in the market for audio equipment and took a few minutes to understand what the oddly named buttons do (don’t be intimidated by the jargon, your grand kids can explain it to you).

I’d always sort of wondered what the IT guys had to do to set up a network. Now I know, and its not so easy as you think; more like “plug and kind of play after a few frustrating false starts” rather than “plug and play”. But having been through it, I’ve gained some insight into the workings of the control networks I use as tools every day in addition to knowing my way around my home network.

After my adventure, I have a lot of practical knowledge and experience, a working “high tech” wiring system in my home and office, and renewed respect for the folks who do that sort of thing professionally. And that’s probably good for everyone when we work together in out in the field.


David Sellers
Senior Engineer – Facility Dynamics Engineering

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3 Responses to Learning By Doing

  1. Teqniqal says:

    “Learning by doing” reminds me of a treatis postes on the company bullitin board about this subject. There was a phrase “Involve me and I will learn” to which someone had drawn a line through the word “Involve” and replaced it with the word “Invoice”. “Invoice me and I will learn.”

  2. Nice post, David. I’m reminded of wiring my first circuits in college lab. Before then, the only experience I had with electricity was flipping switches and replacing batteries and lightbulbs. There’s an awkwardness to physical learning that feels like wading in water up to your chest, which gradually decreases with practice and repetition. Your post also reminds me of “gumption traps” in Zen and the Art of Motorcycle Maintenance, where, before monkey-fisting the head off a stuck bolt, you might as well put the wrench down and figure out a better solution (like buying the special tools needed for working with a punch down block. CHEERS!

  3. felicity says:

    learning by doing is one way the other very gud.and would like to involve myself.thank you.

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