A colleague has stumped me with the following question. ================== A supplier of a Photovoltaic panel cited IEC 61140 (Protection against electric shock – Common aspects for installation and equipment) as referencing a "safe" voltage to be as high as 120 Vdc. This is puzzling because UL 1703 (Flat-Plate Photovoltaic Modules and Panels) appears to define the electric shock threshold at 30 Vdc. How can electric shock threshold for UL 1703 be set at 30 Vdc, but IEC 61140 considers the upper "safe" limit to be 120 Vd.c.?
*************************************************************************************************************** IEC 61140 - Protection against electrical shock - common aspects for installation and equipment Section 7.4 Class III Equipment Equipment relying on limitation of voltage to ELV values as provision for basic protection and with no provision for fault protection. 7.4.1 Voltages 7.4.1.1 Equipment shall be designed for a maximum nominal voltage not exceeding 50V a.c. or 120 V d.c. ripple free. ... NOTE 2: According to clause 411 of IEC 60264-4-41, class III equipment is accepted only for connection to SELV and PELV systems. ***************************************************************************************************************** Any ideas on the rational behind this difference? Regards, Lauren Crane Product Regulatory Analyst Corporate Product EHS Lead Applied Materials Inc. Austin, TX 512 272-6540 [#922 26540] - external use - Save paper and trees! Please consider the environment before printing this e-mail.
