A Five-Part Resistor-Capacitor Network for Measurement of Voltage and Current Levels Related To Electric Shock and Burns

ABSTRACT This paper discusses the development of a five-part equivalent body impedance and reaction network which can be used to more accurately relate leakage current and voltage measurements to electric shock than do conventional methods. Measurements of body impedance were made on people over a frequency range of 30Hz to 1 MHz, using four methods, to define body impedance values for various conditions of contact. The advantage of the network is that the current in the body impedance section is the actual current which would be expected if a person made the contact, regardless of source impedance, wave shape, frequency, or combination of mixed frequency currents. Calculations of body response to voltage, using the network, show that the frequency of maximum electric shock from voltage contact lies between 500Hz and 3kHz instead of 50 to 60Hz. This effect was verified on several people with an “Involuntary Squeeze Test” which measured the voltage required for muscular contractions of the hand up to 20kHz. The squeeze point is a reference intensity of electric shock near the point of inability to let go. Application of the network to mixed frequencies is discussed, and measurements on people in which 60Hz currents were mixed with currents at frequencies between 30Hz and 100kHz are presented. This data and a comparison of electric shock effects from sine and square waves indicate that the network peak indicated current is the value which most accurately relates to electric shock. Information on leakage current burn related limits and their measurement with the five-part network is also included. The network actual current in mA RMS can be related to electric burns.