Hi Joe:
IEC 60335-1 (2013 edition) defines a Class III product as not having any voltage exceeding SELV. SELV is defined in 335 as 42 volts rms and no-load voltage as 50 volts rms (3.4.2). Your 60 volts exceeds the 42 volts SELV limits between conductors, but does not exceed 42 volts to earth (because the product is battery-powered and has no connection to earth). So, your product is Class II. Since the 60-volt circuit is internal, chances are the construction is double-insulated. I assume the product (and the 60 volts) is not connected to earth. If this is the case, then, for an electric shock, the body must contact both poles of the 60 volts at the same time. But, both poles are insulated from accessible conductive parts - TWO insulations! Both must fail at the same time. Voila, double insulation! Touch current (leakage current in the 335 standard) does not apply because it is measured to a pole of the supply (13.2). Since your product is not connected to the supply, leakage current is not measurable. However, two electric strength tests are required, one from the battery (500 volts) and the other from the 60 volts (1000 volts) to accessible parts or foil wrapped about non-conductive parts (Table 4). If you measure the pole-to-pole leakage current of the 60-volts, chances are the 1,500-ohm load will stop the generator so the current will be near zero. This may demonstrate a protective impedance in accordance with 8.1.4. The 60-volt supply may not be "live." As with leakage current, the 8.1.4 measurements are made to one pole of the supply, which, as before, means that the current is not measurable. Maybe this discussion is of some help, Rich From: Joe Randolph <j...@randolph-telecom.com> Sent: Thursday, January 9, 2020 1:32 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Touch current in IEC 60335-1 for Household Appliances I've been asked to review a handheld product for compliance with the 2009 edition of IEC 60335-1 (Household Appliances). This is not a standard that I normally work with, but it's the one I have been asked to use. A question has come up regarding touch current. While the appliance is powered from a 3V battery, there is an internal circuit that steps this up to more than 60 volts. I'm finding that clause 3.3.12 of the 2009 edition of 60335-1 has some confusing wording about whether the presence of the internal 60 volt circuit would prevent the product from being treated as a Class 3 appliance, and would instead force it to be treated as a Class 2 appliance. My take on what clause 3.3.12 meant to say is that for a Class 3 appliance, accessible parts must comply with clause 8.1.4. Clause 8.1.4 allows non-SELV voltages on accessible parts, provided that a "protective impedance" is used. This is what seems reasonable to me, but it's not quite what clause 3.3.12 literally says. The present language is a bit self-contradicting. I've looked at how IEC 60950-1 and IEC 62368-1 treat the topic of touch currents, and both standards (particularly IEC 62368-1) seem to have a more modern and comprehensive treatment of touch current than the 2009 edition of IEC 60335-1. I'm curious to know whether there is any effort underway to update the touch current requirements in IEC 60335-1 to be more similar to what now appears in IEC 62368-1 for ITE and Audio/Video products. It would be helpful to know whether any relevant changes are in the pipeline. I'm aware that a 2016 edition of IEC 60335-1 has been published, but it's my impression that the touch current requirements are the same as those in the 2009 edition. Thanks, Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 (USA) j...@randolph-telecom.com <mailto:j...@randolph-telecom.com> http://www.randolph-telecom.com - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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