Equipotential earthing study: equipotential wiring is unnecessary

Technical Note


This study was undertaken to determine the ongoing need for Equipotential (EP) earthing as required in AS/NZS 3003, section 4.4.2. A total of 2279 earth points were tested in four clinical institutions in Body Protected areas (as defined in AS/NZS 3003). Each earth point was tested for potentials existing in the earthing in order to assess whether any potentials exceeded the 100 mV requirement of AS/NZS 3003 for EP earthing. The voltage measured was 1.21 mV +/-3.59 mV, (mean +/- standard deviation (SD)), with a of 99 % confidence interval between 1.0 mV and 1.4 mV. This study suggests that the requirements for EP earthing in section 4.4.2 of AS/NZS 3003 are unnecessary. It is further suggested that Standards Australia review these requirements with the view of withdrawing them from the Standard.

Key words

equipotential earthing micro-electrocution electrical standards 


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Copyright information

© Australasian College of Physical Scientists and Engineers in Medicine 2004

Authors and Affiliations

  1. 1.Graduate School of Biomedical EngineeringUniversity of New South WalesSydneyAustralia
  2. 2.Clinical EngineeringPrince of Wales HospitalRandwickAustralia

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