In message
<b87b3216c599564e9071daf63e06e7491eab4b8...@exchange.wonderwarene.com>,
dated Sun, 7 Sep 2014, John Cochran <[email protected]> writes:
Actually I need to meet the standard for outdoor enclosures, UL
60950-22, and clause 6.1 refers back to UL 60950-1 clause 2.2.2 and
2.2.3. The difference is the voltage limits are reduced, due to
contact resistance of the body being reduced when subjected to wet
locations. The clause states the voltage difference under a single
fault must not exceed 30 V ac, without any mention of current. Am I
reading this correctly?
Probably correctly, but not completely. The missing piece is how the
voltage is measured. If the hazard is 'touch current', then 5.1 of
60950-1 applies. However, 6.1 of 60950-22 doesn't seem to recognize that
the voltage present on user-accessible conductive parts may come from a
high-impedance source, so that it is the touch current and not the
voltage that matters.
Maybe Mr. Nute can throw more light on this.
--
OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk
Quid faciamus nisi sit?
John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
-
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