Hi Ted, It is not exactly true that if fire enclosure complies with IEC 60950-1 it will also comply with IEC 62368-1, except if you use the statement from clause 4.1.1.
IEC 62368-1 has requirements also for top openings and side openings if fire cone from PIS propagates through the opening, while IEC 60950-1 only required to make 5% projection from the PIS. So openings that were OK for IEC 60950-1 are not necessarily OK for IEC 62368-1. Alternative methods of opening evaluation by fire test are not really practicable in my opinion, especially for the unit with air flow. Best regards, Bostjan On 29. jun. 2016, at 19.33, Ted Eckert <[email protected]<mailto:[email protected]>> wrote: Hello Brian, This is a fairly simplistic view, but it’s the best I can do without copying whole sections of the standards. It takes some time to learn the new standard, but it may be well worth getting a copy to go over if you will be using it in the future. IEC 60950-1 has requirements that go back to the days when transformers and other components were sealed with waxes and varnishes. There are other assumptions based on materials that used to be common but are now rarely used. Many of the fire enclosure requirements were based on the assumption that these materials could melt, catch on fire and drip out of the enclosure. The requirements are partly based on the concept of looking at the failure modes of the past and designing them out. IEC 62368-1 carries over many of the IEC 60950-1 fire enclosure requirements as an option for compliance, but there are options to use other constructional requirements that could give designers more flexibility. Potential ignition sources are determined based on either energy levels or other factors such as arcing. These potential ignition sources must be provided protection, but it can be handled differently. You will need to look at the standard to learn about concepts such as the fire cones. Designers have more options for ways to isolate ignition sources. They can have separation through barriers or distance. It’s not easy to describe, but the designer should be able to do things that were not previously allowed. There are certainly more options that allow for better airflow and cooling that would have been difficult under IEC 60950-1. The IEC 60950-1 requirements are included partly to make it easier to ensure that IEC 60950-1 fire enclosures will meet IEC 62368-1 with! out going through more work. However, if you are willing to do the work, you will see that there is more flexibility in the design options if you use the new requirements over the old. Ted Eckert Microsoft Corporation The opinions expressed are my own and do not necessarily reflect those of my employer. From: Kunde, Brian [mailto:[email protected]] Sent: Wednesday, June 29, 2016 9:24 AM To: [email protected]<mailto:[email protected]> Subject: Re: [PSES] [BULK] Re: [PSES] Fire requirements in standards IBM Ken, My main interest at this time is with the fire enclosure. Our products fall under the 61010-1, and it’s been years since I have read 60950, but I can see where improvements in the constructional requirements in a fire enclosure could be made. It seems our mechanical engineers sometimes struggle to understand the requirements of Fire Enclosure, RF Enclosure, Limit Access for electric shock, etc.. 61010-1 always seems to be lagging so I was hoping to learn as much about future improvements as I can to give more time to train our engineers. Thanks, The Other Brian From: IBM Ken [mailto:[email protected]] Sent: Wednesday, June 29, 2016 11:32 AM To: Kunde, Brian Cc: [email protected]<mailto:[email protected]> Subject: [BULK] Re: [PSES] Fire requirements in standards Importance: Low Hi Brian; Do you mean specifically the changes to the fire enclosure requirements or the overall differences between 60950 and 62368? If it's the latter, ECMA TR/106 might be helpful (but be forewarned, this document compares 60950 to the 1st edition of 62368). The best part is that it's free! http://www.ecma-international.org/publications/files/ECMA-TR/ECMA%20TR-106.pdf On Wed, Jun 29, 2016 at 8:53 AM, Kunde, Brian <[email protected]<mailto:[email protected]>> wrote: This subject is very interesting to me. If I wanted to know more, is getting a copy of 62368-1 worth reading or will I have to wait for the proposed changes to 60950-1 to come out, or what do you recommend? Are the proposed changes quite large or can they be summarized? What are the weak areas of the current construction requirements? I would like to inform our mechanical people as soon as possible of changes like these. Regards, The Other Brian -----Original Message----- From: Richard Nute [mailto:[email protected]<mailto:[email protected]>] Sent: Tuesday, June 28, 2016 3:23 PM To: [email protected]<mailto:[email protected]> Subject: [PSES] Fire requirements in standards > During last TC 108 meeting there was no real consensus > about this topic. Also there was an issue raised that fire > enclosure of some product will fail requirement of new > standard while it was OK for IEC 60950-1 and they will > make a proposal to change the requirement in the standard. This is true. A new standard implies that some aspects of the old standard are inadequate. 62368-1 is better at preventing fires and preventing escape of fires than 60950-1. Changing back to 60950-1 means continued fire incidents. I have said many times that fire is our biggest problem. See the weekly recall list from In Compliance magazine. Best regards, Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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