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Ethernet stuff is not intended to run outdoors like regular telephones. The biggest risk these days is picking up static electricity when the cables are pulled through conduits and wiring troughs. That seems to get worse the better the cabling gets (cat5E and up) due to triboelectricity.
The insulation scheme was chosen to accommodate ground level shifts within building premises wiring (different AC feeds to different boxes). The wiring cables float (up to 2250 VDC) with respect to ALL of these. There has been much discussion in the 802.3af work group on how to handle DC-powered cables. The 802.3 standard defines two environments ("A" and "B") with respect to port-to-port isolation (See 802.3 spec or some of the 802.3af presentations on the IEEE public site).
You are supposed to used fiber optic links if you exit a building. IP phones are supposed to be within a building, with the only wiring going to an Ethernet hub. Wall warts if used are double insulated.
The 2kV caps are not supposed to be leaky.
Larry Miller
-----Original Message-----
From: Dieter Knollman [SMTP:djhk@xxxxxxxxxx]
Sent: Friday, September 15, 2000 9:53 AM
To: stds-802-3-pwrviamdi@xxxxxxxx
Subject: Static Discharge
Hi,
My background is telephony. I'm totally new to 802.3, so please excuse
my ignorance.
One thing that appears strange is the lack of an intentional discharge
path for the potential on the cable.
The only means that I have found is breakdown of the common mode
termination capacitors.
Are these caps with 2 kV rating intended to be leaky?
On POTS line interfaces the Tip lead is typically biased around ground
and serves as a discharge path to earth ground for Analog Sets. Do the
IP Phones require a discharge path via the LAN?
Dieter Knollman
DMTS
Lucent
djhk@xxxxxxxxxx