More words (opinions) on this issue...... The "scope" of IEC 60950 does not establish a lower voltage limit. Section 1.1.1 states "This standard is applicable to mains-powered or battery-powered information technology equipment ....with a rated voltage not exceeding 600V."
Section 1.2.4.3 simply defines Class III equipment as that which protects against electric shock by SELV, i.e. non-hazardous voltages. It does not exclude such equipment, due to other possible hazards. Section 1.2.8.3 defines hazardous voltages as those above 42.4V peak or 60Vdc. Section 1.2.8.4 indirectly defines SELV as circuits meeting these requirements. It is my opinion that "battery-powered" equipment, albeit low voltage, is included in the scope due to the hazards unique to such equipment. The energy stored within the batteries can (and has) resulted in fires within laptop PCs due to an accidental short. The possibility of a burn hazard has already been mentioned. If a Class III ITE device contains no batteries, and is powered by a "limited power source (section 2.11) it requires no fire enclosure (section 4.4.5.2). As such, the only hazards remaining to be avoided are sharp edges etc. This is why it is not mandatory (under the scope), nor practical, to "certify" such devices to IEC 60950. Having said this, there may be other reasons to "certify, e.g. value of agency follow-up services distant (e.g. Far East) factories, customer expectations, and so on. George Alspaugh Lexmark International Inc. --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
