steve weir wrote: > if we have a big installation, and we use non-isolated connections, like RS-485 shields between rooms, we can be right back to getting really big currents flowing in the shields. Years ago I worked at a plant that had such bad shield current problems between adjacent equipment rooms that ther installations were tied with huge (I mean, 2 inch diameter) jumper cables. Still, the cables were always warm to the touch!!! ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Martin Euredjian eCinema Systems, Inc. voice: 661-305-9320 fax: 661-775-4876 martin@xxxxxxxxxxxxxx ecinema@xxxxxxxx www.ecinemasys.com ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu