[SGVLUG] Buying a spool of ethernet wire - cat5e or cat6? Copper or aluminum? Where? How much?

[Stan Slonkosky]

On Mon, Jul 30, 2012 at 2:14 PM, Dan Kegel <dank at kegel.com> wrote:

> I finally used up my old spool of cat5 (loaning it to
> friends, wiring up my garage, etc.), and
> I need to wire up some network outlets in my new house
> (powerline networking #fail).  So time to buy a new
> spool.
>
> That brings up a few questions:
>
> 1) cat5e, or cat6?  cat5e should be sufficient for gigabit.
>

If you use Cat5e connectors on Cat6 cable it will perform like Cat5e.

There was an interesting interview with Stephen H. Lampen, MultiMedia
Technology Manager at Belden on the now discontinued "This Week in Radio
Tech" podcast on Leo Laporte's TWiT network. He says they sell the jacks,
but not the plugs. While you can attach a Cat5e connector easily enough.
Attaching Cat6 plugs in the field is difficult. Attaching Cat6a plugs is
the most difficult thing they do at the Belden factory, so you can forgot
about doing that in the field. This discussion starts about 38 minutes in:

http://twit.tv/show/this-week-in-radio-tech/111-0

Somewhere in the podcast he mentions that solid wire will always perform
better than stranded though the stranded will probably cost twice as much.
The only reason to use stranded is because you need flexibility.


> 2) Copper, or copper-clad-aluminum?  Aluminum would probably be
> annoyingly stiff.
>
> In a screencast done in May, Mike Pennacchi discusses a problem that they
had setting up for Interop New York a few years ago. They had purchased a
couple of pallet loads of no-name cable and discovered that network signals
made it through but POE did not. They tested arun of cable on which
ethernet worked but the POE did not. They tested a 200' section of it with
a Fluke Networks cable analyzer and found that it had a negative insertion
loss and a negative return loss (e.g., fail). Also each wire had a
resistance between 50 and 55 Ohms. They tested a known good cable of the
same length and found it had both a positive insertion loss and a positive
return loss and the resistance of each wire was about 11.5 Ohms. It turns
out that the cable that they had problems with was copper-clad aluminum.
Mike also mentioned that the bad cable didn't perform as well at lower
frequencies. This would be consistent with the skin effect in which higher
frequency currents mostly flow on the surface of conductors.

This is discussed about 20 minutes into the screencast:

http://www.screencast.com/t/dpqDKx0keB

-- 
Stan Slonkosky
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