RE: Wiring folks out there?

>1) Stay away from the electrical wiring with your CAT-5 runs.  Not just for
>safety, but if your runs are within 6" or so of AC wiring and run parallel
>to it for any length, the AC resonance can wreak havoc on data integrity.

Most references I've seen suggest a 12" separation between AC and ethernet
for extended parallel runs.  If they need to cross, 90 degree crossings are
preferred.  In a pinch for a short distance (say under 3-4 feet) you can
probably get away with 6" or less spacing between the AC and ethernet.  The
other factor is noise level on the AC line the ethernet is near to.  Big
motors (like vacuum cleaners and washing machines) can produce a lot of
noise on the AC line that may affect other devices, and maybe nearby ethernet.

Some folks have tried fused 120v AC over CAT5's unused pairs to power
wireless access points without experiencing data loss.  (Search the Google
Groups for a discussion about this in 2003 or 2004 and also look for a wiki
page on or linked to from the SWN wiki page.)  I have also tested the 1 amp
fused 120v AC over CAT5 idea, and in my own evaluation no data corruption
occurred.  The low, steady current draw of the wireless APs probably means
the AC line stays relatively clean hence further mitigating the chances of
data corruption.  This said, if someone is thinking of doing fused 120v AC
over CAT5, it may be simply easier and safer for them to use an outdoor
rated extension cord and run that to the location of the outdoor wireless
AP.  What is appropriate to do depends upon the risk assessment of your
various options weighed against the potential benefits.

>2) You are running through walls in a residence. Do yourself (and your
>family) a favor and pay the extra for the Plenum.  It's worth it for safety.

IIRC, plenum rated cable is only need in air-handling spaces.  Risers
(cable runs between floors) have another cable spec.  Plenum rated UTP
needs to be used in suspended ceilings used for air distribution and in air
ducts.  A framed 2x4 stud wall doesn't need plenum cable unless your cable
run will be going through an air handling channel built between the studs.
Lastly it may be cheaper to buy a single 500' or 1000'spool of plenum cable
for all your uses then to buy multiple smaller spools.

>> You shouldn't need shielded cable.  UTP, or Unshielded Twisted Pair,
>> should work just fine.  I suppose if you're going through the walls
>> and you want to make the fire marshall happy you'll want cable that
>> is plenum rated, which costs about 4x as much as regular UTP.

I believe that shielded cable will only provide a benefit if it is grounded
correctly, in order to drain off any stray energy the shield picked up.
Correct grounding requires care so that ground loops are not created and
that differences in ground potential are minimized.  Unless your home is an
high power transmission station or an electrically noisy factory (heavy
electrical equipment with high duty cycles), you probably don't need STP.

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