POE networking, what's the range?

perryh at pluto.rain.com perryh at pluto.rain.com
Sat Oct 7 20:38:46 PDT 2006

> > The garage and the house are over 1/10 of a mile apart?
> yeah. it's not a car garage.
> I don't plan to string cable at all. Cable is already in place
> for all the electric stuff.

IOW the cat5 between the buildings is already in place?  In that
case, and supposing whoever put it in knew what s/he was doing,
the safety issues should have been taken care of.

There's still the matter of the 100m distance spec, but as others
have mentioned that is not a hard and fast rule in practice.
I have personally seen 10Base-2 (RG58 coax) work very well on a
segment that was well over twice the 200m maximum length specified
for that technology.  If 10/100Base-T are equally robust, you might
get by with a 200m run (esp. if you run only 10Mb over cat5, which
is capable of handling 100Mb, and/or if nothing else in the same
collision domain has anywhere near a maximum-length run).

I would guess that POE might still have problems, separate from
the Ethernet signal-distance limits, due to power loss in the
wiring.  The POE-powered device would likely have been designed
to allow for the loss in 100m of the cat 5 pair that's being used
to supply the power.  You've got about twice that distance, thus
about twice the voltage drop at any given current consumption.

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