Worth reading by anyone who is interested in understanding more about
practical aspects of protection against electric shock and the setting of
acceptable limits.

This 2010 discussion paper gives extremely valuable insight into factors
which affect the setting of safety standards for electric shock and how
acceptable voltage/current/waveform  combinations are established. Having
looked through this I feel far happier than I was previously about recent
changes in regulatory limits.

http://www.ifmqs.com.au/images/CTL%20presentation%20Peak%20TC+attachments.p=
df



      Russell McMahon

   Abstract:

IEC 60990, 'Measurement of touch current and protective conductor current',
provides the details needed to properly implement Touch Current measurement=
s
in products.
In this standard under the discussion of measurement to touch
current it states: Of the responses, perception/ reaction and let-go are
related
to the peak value of touch current and vary with frequency.  Traditionally,
concerns for electric shock have dealt with sinusoidal waveforms, for which
rms
measurements are the most convenient.  Peak measurements are more
appropriate for non-sinusoidal waveforms.
This comment has always been intended to be used by knowledgeable electrica=
l
engineers or other professionals involved
in the development and use of  technical standards for evaluation of
equipment with reference to electric shock.
The expectation has always been that invoking the IEC 60990
Touch Current measurement circuits and methods would involve common sense
and that the proper measurement would
be based upon the waveshape.
A comparison of the implementation of this Touch Current measurement in
several standards is discussed in this paper.
--=20
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