In a posting dated 1/8/2004, I wrote: > Now I go to Annex ZB and look at the deviations to clause > 6.1.2.2 for Finland, Norway, and Sweden. The exclusions > described here are much more restrictive, limited to > permanently connected equipment or pluggable equipment type > B, used in restricted access locations where equipotential > bonding has been applied. In other words, a telephone > central office or *maybe* the main telephone closet in an > office building. Certainly, no stretch of the imagination > would have this clause include the typical office environment.
Hello All: Okay, I re-read the wording of the Annex ZB deviation to clause 6.1.2.2 of EN 60950-1, and I think I have developed a partial answer to my own question. I see that I missed the word "and" in one place and perhaps misinterpreted the meaning of "and" in a second place. After reading the clause carefully several times, I think it is saying that exclusions are available for four separate cases: 1) Permanently connected equipment. 2) Pluggable equipment Type B. 3) Equipment used in a restricted access location that has equipotential bonding. 4) Equipment that has provisions for a permanently connected protective earthing conductor and is provided with instructions for installation of that conductor by a service person. In the wording of Annex ZB, note that the "and" between cases 3 and 4 could be interpreted to be merging them into a single case, rather than establishing case 4 as a standalone case. So, the liberal interpretation is that case 4 is a viable, standalone option, similar to the 6.1.2.2 text in the main body of the standard except for the specific reference to having a service person install the ground conductor. Even with the reference to the service person, this case provides enough wiggle room to allow the equipment to be used in a normal office environment. The conservative interpretation merges cases 3 and 4 into a single case and pretty much excludes the normal office environment if the AC mains connector is pluggable Type A. I'm still interested to know what other list members think this means for the case I described in my earlier posting. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) [email protected] http://www.randolph-telecom.com This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
