I am the author of that wire table. As an interesting aside, you will find that if you multiply the max current by the ohms/1000' for any given wire size you will come up with 24 volts as the voltage drop. To get lower voltage drop, go to a thicker wire gauge. Fr. Thomas McGahee ----- Original Message ----- From: "Mitch Miller" To: Sent: Friday, April 05, 2002 10:26 AM Subject: Re: [PIC]:RS485 supply > On Fri, 5 Apr 2002, Micro Eng wrote: > > > Speaking of CAT5....how much current at 5V can you push thru it? > > Well, according to > http://www.pupman.com/listarchives/1998/April/msg00222.html, 24 gauge wire > (Cat 5 is 24 gauge, isn't it?) should not exceed 0.9214 amps, and says it > has a resistance of 25.7 ohms / 1000'. So ... for a 1000' RS-485 line, > you're going to lose about 24V just to wire loss ... Ouch! Guess that > also makes a pretty good heater! (21 Watts of loss to heat). > > -- Mitch > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body