Pre-Wiring Traps to Avoid

I'm in the process of remodeling an older home. I just finished pre-wiring for audio, video, voice, data and security purposes. Several ideas came to mind.

First off, installers working in newer homes should consider what insulation will be installed. Fiberglass batting is still quite common but, more and more, folks are getting sprayed-in foam insulation.

The concept for the homeowner is simple: not only do you have the insulation value, but drafts are generally cut down since the foam tends to seal everything quite nicely.

By taking precautions, here are a couple pre-wiring traps you could avoid.

Dealing with Goo

An installer friend was telling me about an instance where he had pre-wired a home for the works and the insulation sprayer put two passes of insulation in the walls. The Cat 5e wire that he installed had tested fine before the walls were insulated, but after the insulation crew left, one of the runs showed multiple flaws.

Using a TDR tester, he was able to locate the spot on the wire where the flaw occurred, and surgery was performed. The outer jacket of the wire was fine, but when he cut into the cl3 jacket, he found that the inner insulation on the individual strands had melted.

It turns out the insulation gives off a certain amount of heat when it's setting up. When the second coat was applied, it essentially kept the first layer's worth of heat trapped inside the wall where it did its trick.

One solution is to tell the insulators to go easy on the goo. That doesn't always work.

Run Empty Conduit

Perhaps a better solution is to run empty conduit to likely locations, so that the installer can go back in afterward and pull whatever wires might be required. Carlon makes a variety of sizes of tubing for this purpose, and it works very well. It even includes a length of nylon pull-tape in the tube to save the installer time.

The Carlon tubing also provides another benefit: it's probably the most future proof wiring scheme I can think of. Consider that over the past 15 years the industry has offered up composite video, S-video, VGA and its variants, component video and its iterations, DVI and HDMI as wiring alternatives.

I feel a little safer knowing that I've got a plan B in my back pocket when a new format stumbles across the threshold and says "You've got to use me if you want the best picture and or sound."

Running this type of tubing between equipment racks and the demarcation point in the home where the voice, data and cable products enter allows for on-the-fly changes without having to cut through Sheetrock and sprayed-in foam. You'd be well advised to also install that same tubing between the rack and the video display, as well as the rack and the attic and/or basement and between major nodes in the home.

Test your wiring before and after other trades visit the site, and give yourself a way out for the inevitable future modifications coming around the bend.