If we access the safe DC voltage, 42 Vdc is safe to avoid electrical shock hazard. If we use this voltage to judge if the product needs to comply with the safety standard, it may not be appropriate. We all have learnt that battery-operated products have serious incidents causing injury to the users >from time to time. The current safety standards seem not to take this care too much and most of testing laboratories take the advice from the safety standard: Battery-operated products are outside the scope of the safety standard and is safe to be used without the compliance with safety standard.
Regards, Scott On 03/02/2011 5:42 AM, "Ted Eckert" <[email protected]> wrote: Hello Lauren, IEC 60335-1 defines safety extra-low voltage as not exceeding 42 V between conductors and earth, with a no-load voltage not exceeding 50 V. It also places fairly onerous requirements on the power supply for SELV. It further states that accessible parts are not considered to be live if they are not supplied by SELV with some added conditions. The standard does allow access to higher voltages if they are impedance limited. It isn’t exactly the same as 60950-1, but it has similar intentions. The part 2 documents each cover specific product types. I have only worked with IEC 60335-2-34 for motor compressors and 60335-2-40 for air conditioners. Both of these parts leave the part 1 definition of electrical hazards unchanged. Regards, Ted Eckert Compliance Engineer Microsoft Corporation [email protected] <mailto:[email protected]> The opinions expressed are my own and do not necessarily reflect those of my employer. From: Joe Randolph [mailto:[email protected]] Sent: Wednesday, February 02, 2011 12:44 PM To: [email protected] Subject: Re: 60335 safe DC voltage On 2/2/2011, Lauren Crane wrote: I am in a discussion with a colleague asserting that EN/IEC 60335 provides that a DC voltage up to 120V can be considered safe under dry conditions. Since most other standards I deal with set the limit of safe DC at 60V, I wonder if he has read a typo or if there are other conditions surrounding this level. I do not yet own a copy of 60335 but I know it has *many* parts. Can anyone say if 60335 concept of safe voltage is defined in part 1 or do different appliance types get different treatment in this regard? Hi Lauren: I don't have a copy of 60335, but I know of two instances in EN 60950 where voltages above 60 VDC are not considered hazardous voltages: 1) In a "Limited Current Circuit," voltages over 60 VDC are allowed but there are strict limits on the available current. 2) In a TNV-2 or TNV-3 circuit (targeted at analog phone lines), DC voltages up to 120 VDC are allowed, but there are some restrictions on accessibility. Maybe one or both of these two classifications appears in some form within 60335. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) [email protected] http://www.randolph-telecom.com <http://www.randolph-telecom.com/> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]>
