Vijay, I have posted my opinions within brackets [ ] in your note below. "Wani, Vijay (V)" <vwani%[email protected]> on 04/20/2002 08:38:51 PM Thank you all for your valuable input. i apologize for late reply. i ordered a copy of EN60950:2000. (thanks, Chris, George and constantin) and now, it is getting much clearer. however, i have some questions and would appreciate any comment. as per EN60950:2000, 4.7.2.1: 1. Except where method 2 of 4.7.1 is used exclusively, or as permitted in 4.7.2.2, the following parts are considered to have a risk of ignition and, therefore, require a FIRE ENCLOSURE: - components in PRIMARY CIRCUITS; So if i am interpreting Rich and Scott's e-mail right (great explanation), i do not need FIRE ENCLOSURE, if primary circuit is supplied by a Limited Power source. For an existing device, how do i know whether the primary circuit is supplied by a Limited Power source? are cell-phones, PDA's typically supplied by Limited Power Source? [The type devices you list are typically battery powered. The output of batteries can often be totally unlimited, thus fire hazards. However, a current limiting device may be used to obtain a "limited power source". One way to determine what is the case is to buy the product and test the battery power to the conditions for limited power source.] as per 4.7.3.4 2. Inside FIRE ENCLOSURE, materials for components and other parts, (including MECHANICAL and ELECTRICAL ENCLOSURE located inside FIRE ENCLOSURS) shall comply with on of the following: - be of FLAMMABILITY CLASS V-2 OR FLAMMABILITY CLASS HF-2; OR - pass the flammability test described in clause A.2; or - meet flammability requirements of a relevant IEC component standard which includes such requirements. Does this mean; if i have an enclosure inside a FIRE ENCLOSURE, than it has to be V-2 eventhough there are no safety hazards resulting from complete disapperance of the enclosure? [Simple answer is "yes". There are exeptions listed immediately following the text you included above, e.g. parts mounted on materials of flammability class V-1.] thank you. vijay wani ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ 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://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
