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I wasn't raising an issue, Bob.
Dieter was just asking how Ethernet avoided the Telco grounding, and I was explaining "what it is". At least, that's what I intended.
Roger seemed to think I was taking a position of some sort. Look at Dieter's post, then mine.
Cheers,
Larry
-----Original Message-----
From: RDLove [SMTP:rdlove@nc.rr.com]
Sent: Friday, September 15, 2000 12:09 PM
To: 802.3af
Subject: Fw: Static Discharge
I meant to send the attached to all 802.3af. Sorry for the duplicate email to you, Larry.
Best regards,
Robert D. Love
President, LAN Connect Consultants
7105 Leveret Circle
Raleigh, NC 27615
Phone: 919 848-6773
Fax: 720 222-0900
email: rdlove@ieee.org <mailto:rdlove@ieee.org>
----- Original Message -----
From: RDLove <mailto:rdlove@nc.rr.com>
To: Larry Miller <mailto:ldmiller@nortelnetworks.com>
Sent: Friday, September 15, 2000 3:07 PM
Subject: Re: Static Discharge
Larry, thanks for your input. I agree with all you say, but still don't know if this is an issue that needs to be addressed. I would like to hear from other experts on it.
Best regards,
Robert D. Love
President, LAN Connect Consultants
7105 Leveret Circle
Raleigh, NC 27615
Phone: 919 848-6773
Fax: 720 222-0900
email: rdlove@ieee.org <mailto:rdlove@ieee.org>
----- Original Message -----
From: Larry Miller <mailto:ldmiller@nortelnetworks.com>
To: Dieter Knollman <mailto:djhk@lucent.com> ; stds-802-3-pwrviamdi@ieee.org <mailto:stds-802-3-pwrviamdi@ieee.org>
Sent: Friday, September 15, 2000 1:07 PM
Subject: RE: Static Discharge
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@lucent.com]
Sent: Friday, September 15, 2000 9:53 AM
To: stds-802-3-pwrviamdi@ieee.org
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@lucent.com