03/523724 DC : DRAFT JUNE 2003

1 Scope and object
2 Normative reference
3 Definitions
  3.1 General Definitions
      3.1.1 longitudinal current: Current flowing lengthwise
             through the trunk of the human body such as from
             hand to feet
      3.1.2 transverse current: Current flowing across the trunk
             of the human body such as from hand to hand
      3.1.3 internal impedance of the human body (Zi): Impedance
             between two electrodes in contact with two parts of
             the human body, neglecting skin impedance
      3.1.4 impedance of the skin (Zs): Impedance between an
             electrode on the skin and the conductive tissues
             underneath
      3.1.5 total impedance of the human body (ZT): Vectorial
             sum of the internal impedance and the impedance of
             the skin
      3.1.6 initial resistance of the human body (RO): Resistance
             limiting the peal value of the current at the moment
             when the touch voltage occurs
      3.1.7 dry condition: Condition of the skin of the surface
             area with regard to humidity of a person being at
             rest under normal indoor environmental conditions
      3.1.8 waterwet condition: Condition of the skin of a surface
             area of contact being exposed for one minute to water
             of public water supplies (average resistivity rho =
             3500 omegacm, ph = 7 to -9)
      3.1.9 saltwet condition: Condition of the skin of a surface
             area of contact being exposed for one minute to a
             3% solution of a NaCl in water (average resistivity
             rho = 3500 omegacm, ph = 7 to 9)
      3.1.10 deviation factor FD: is the total body impedance for
             a given percentile rank of a population divided by the
             total body impedance ZT for a percentile
             rank of 50% of population at a given touch voltage
   3.2 Effects of sinusoidal alternating current in the range 15
       Hz to 100 Hz
       3.2.1 threshold of perception: Minimum value of current
             which causes any sensation for the person through
             which it is flowing
       3.2.2 threshold of reaction: Minimum value of current which
             causes involuntary muscular contraction
       3.3.3 threshold of let-go: Minimum value of current at which
             a person holding electrodes can let go of the electrodes
       3.3.4 threshold of ventricular fibrillation: Minimum value
             of current through the body which causes ventricular
             fibrillation
       3.2.5 threshold -current factor F: Relates the electric
             field strength (current density) in the heart for
             a given current path to the electric field strength
             (current density) in the heart for a current of equal
             magnitude flowing from left hand to feet
       3.2.6 vulnerable period: Covers a comparatively small part
             of the cardiac cycle during which the heart fibers
             are in an inhomogeneous state of excitability and
             ventricular fibrillation occurs if they are excited
             by an electric current of sufficient magnitude
   3.3 Effects of direct current
       3.3.1 total body resistance (R[T]): Sum of the internal
             resistance and the resistances of the skin
       3.3.2 d.c./a.c. equivalence factor (K): Ratio of direct
             current to its equivalent r.m.s value of alternating
             current having the same probability of inducing
             ventricular fibrillation
       3.3.3 upward current: Direct current through the human
             body for which the feet represent the positive
             polarity
       3.3.4 downward current: Direct current through the human
             body for which the feet represent the negative
             polarity
4 Electrical impedance of the human body
  4.1 Internal impedance of the human body (Z[I])
  4.2 Impedance of the skin (Z[S])
  4.3 Total impedance of the human body (Z[T])
  4.4 Initial resistance of the human body (Z[O])
  4.5 Value of total impedance of the human body (Z[T])
      4.5.1 Sinusoidal alternating current 50/60 Hz for
            large surface areas of contact
      4.5.2 Sinusoidal alternating current 50/60 Hz for
            medium and small surface areas of contact
      4.5.3 Sinusoidal alternating current with frequencies
            up to 20 kHz
      4.5.4 Direct current
  4.6 Values of the initial resistance of the human body (R[O])
  4.7 Effect of current on the skin
5 Effects of sinusoidal alternating current in the range
  15 Hz to 100 Hz
  5.1 Threshold of perception
  5.2 Threshold of reaction
  5.3 Immobilisation
  5.4 Threshold of let-go
  5.5 Threshold of ventricular fibrillation
  5.6 Other effects of current
  5.7 Description of time/current zones
  5.8 Application of heart-current factor (F)
6 Effects of direct current
  6.1 Threshold of perception and threshold of reaction
  6.2 Threshold of immobilisation and threshold of let-go
  6.3 Threshold of ventricular fibrillation
  6.4 Other effects of current
  6.5 Description of time/current zones
  6.6 Heart Factor
Annex A Measurements of the total body impedance Z(T) made on
        living human beings and on corpses and the statistical
        analysis of the results
Annex B Influence of frequency on the total body impedance Z(T)
Annex C (normative)
Total body resistance (R[T]) for direct current
Annex D (informative)
Examples of calculation of Z[T])
Annex E (normative) - FIGURES
Annex F (informative)
Bibliography
Clause 4
Clause 5
Clause 6

IEC 60479-1 TS Ed.4.0