Try section 7 of Bellcore GR-1089-CORE. It allows as much as 200 VDC from tip or ring to ground provided that the current when measured tip to ground or ring to ground does not exceed 10 mA (Class A3). In reality, vendors of central office ISDN typically generate -48VDC 10-20 mA DC for non-span powered circuits, and <-140VDC <135mA DC for span powered circuits. T1 can typically be dry (no DC voltage), -48VDC, or -130/+130 VDC with respect to ground (repeater powering). I am sure there are multiple other schemes, but this is what I am familiar with.
Jim ---------- From: treg-approval To: treg Subject: ISDN and T1 maximum voltage List-Post: [email protected] Date: Wednesday, September 18, 1996 9:06AM Subject: ISDN and T1 maximum voltage Hello fellow TREG'ers, One of my colleagues asked me the following questions and I was unable to provide an answer. I would welcome any help from some one who knows. The question is what is the maximum voltage and current I can expect to get out of a T1 or ISDN line. I know the power isn't very high normally, but how much can the max be? I couldn't find an upper limit. References to the correct standards would be nice. Thanks, Dan Teninty P.E. Senior Design Engineer Product Safety [email protected] FLUKE Corporation Everett, Washington (206) 356-6035 (206) 356-6490 fax
