Todd, There is information (of a sort) <g>. I used to work at GTE, and we designed loops to a "1200 Ohm limit," using various gauges of wire depending on the distance from the CO. So, we can calculate what the "real-life" limits of loop current would likely be, assuming that the telephone had a nominal DC off-hook resistance of 200 Ohms, and the CO used a 200/200 Ohm battery feed (which is universal in the U.S. and Canada--Mexico uses a 400/400 Ohm battery feed in their COs);
the "high average" (assuming a higher voltage on the CO, and a very short loop, so, no loop resistance) would be 52VDC/(200+200+200)=87mA; the "average" (assuming a "medium" loop length of 600 Ohms) would be 52VDC/(200+200+200+600)=42mA the "low average" (assuming a lower CO battery voltage, and a maximum standard loop of 1200 Ohms) would be 48VDC/(200+200+200+1200)=27mA Remember, the internal DC off-hook resistance of the CPE affects that equation--it is typically between 100 and 300 Ohms, more likely 200 Ohms. Also, if the phone line is in rural areas, it is possible that higher voltages would be used with longer loops (higher loop resistance) but the currents would still be about the same at the CPE! - John -------------------------------------------- At 09:48 AM 11/21/96 -0600, you wrote: >Hi Everyone, > >I'm trying to locate statistical information on actual loop current seen on the loop. Is there any information about this distibution with respect to distance from the CO, without going out and actually testing thousands of lines? > >Todd Hurrle Midcom >[email protected] .com >Design Engineer > >---------- >From: Len Goldschmidt[SMTP:[email protected]] >Sent: Wednesday, November 20, 1996 4:50 PM >To: [email protected] >Subject: Re: Part 68, Telco Power Draw > >Hi Roger, > >For loop start, I believe at 48V the nominal current draw is 20mA, max is 70mA. > >>Hey all, >> >>Does anyone know off the top of their heads what is the max power draw >>allowed on the Telco interface according to Part 68. >> >>I guess it is about time I get an updated Part 68! >> >>Thanks, >> >>roger >>[email protected] >> >>"Democracy is the recurrent suspicion that >> more than half of the people are right >> more than half of the time." >> - E. B. White > >______________________________________________________________________________ >Len Goldschmidt Cisco Systems, Inc. \/ [email protected] >Hardware Engineer _/\_ PTT/CES tel: (408) 526-6841 > > > > >Attachment Converted: c:\eudora\attach\RE Part 68, Telco Power Draw > ------------------------------------------------------------------ John Combs, Senior Project Engineer, ITS/TestMark Laboratories Email: [email protected] URL: http://www.testmark.com ------------------------------------------------------------------
