We ground our DS3 connectors at both Xmtr and Rcvr. This is mainly to overcome EMC problems - Emissions/ESD.
Regards, Bandele Jetstream Communications, Inc. badep...@jetstream.com -----Original Message----- From: David Spencer [mailto:dspen...@oresis.com] Sent: Tuesday, August 08, 2000 4:51 PM To: Nebs List Serve (E-mail); TREG (E-mail) Subject: DS3 Grounding for NI to NI Hi All, We have found ourselves in a bit of a quandary over grounding the shields of DS3 connections on our switch. I have the following opinions to date: 1. The DS3 is grounded at the transmitter, always. The Receiver may be grounded or isolated. Selectable is an added feature. 2. Because it is Network Interface (NI) to NI, intra-building, they all get grounded to one another, i.e. bulkhead grounding to frame ground. ANSI T1.102, T1.404, and GR-499 do not give a great deal of guidance. The most applicable is in T1.404, where it says: The shields of the connecting coaxial cables meeting at the NI through the TNC connectors (see 8.2) MAY interconnect the network and CI equipment grounds. Because this is not suitable as the common ground reference, it is necessary that the network and CI equipment be interconnected following appropriate installation procedures consistent with existing safety standards to form the common ground reference. High-frequency pulse isolation transformers may be required at the CI to prevent excessive ground currents in the shields of the connecting cables as shown in figure 5. Figure 5 shows a connection with isolation transformers installed. If the ground loops are not too high (could be an amp or more between frames depending where they are in the building if running a radial ground) I suppose it is not a safety issue. However, when you have multiple DS3's connecting between different frames to your common ground feeder, it seems like it could get ugly as you reinvent the grounding topology. If there is already a mesh network in the building, then I suppose it makes no difference at all. Please advise if you know of any standards, RBOC guidelines/practices/directives, or common practices. This must be a pet issue for someone out there with an opinion. Thanks in advance for your insight! Best Regards, Dave Spencer Compliance Engineer Oresis Communications, Inc. 14670 NW Greenbrier Parkway, Beaverton, OR 97006 * dspen...@oresis.com * http://www.oresis.com * (503) 466-6289 * (503) 533-8233
