Joe, Following fast on the heals of my earlier reply, you can perhaps understand that equipment that is professionally installed is expected to be earthed if required (otherwise the installer could hardly be called 'professional'!).
Similarly, it is expected that an industrial socket to EN60309 (pluggable Type B) will be installed so that its earth connection is connected to the building's earth. Point 3 is for the Central Office of telecoms centres. Again, in such premises it is expected that a 'proper' earth connection will be available. For equipment powered from station office batteries, this is generally a sub-set of 1. Point 4 is not applicable in Europe, as can be seen by looking at EN 60950-1 clause 6.1.2.2, where you will see that it has been removed as a Common Modification. Basically, it is considered that a label on the equipment telling the user to get the equipment professionally installed does not provide an adequate degree of safety (due to the likelihood of such a notice being disregarded). I hope that this is now the end of this topic, but if not I'm more than happy to provide PAID consultation!!! Regards, Richard Hughes www.safetyanswers.ltd.uk Joe Randolph wrote: > > 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 > 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
