Electrical  Resistivity  (ER)  applies  direct  current  or  low-frequency  alternating  current  into  the subsurface  to  determine  the  potential  difference  between  two  points  revealing  the  resistivity and  conductivity  of  the  geological  subsurface  units. This  exploration  technique  is  a  quick  and inexpensive way to image the subsurface while leaving the ground surface unscathed. A number of  electrical  resistivity  arrays  can  be  utilized  depending  on  the  scope and  goals  of  the  project and  can  be  used  independently  or  in  conjunction  with  other  exploration techniques  including borehole  drilling.  Uses  of  ER  exploration  include:  geologic  mapping  of  shallow  bedrock  and permafrost,  volume  estimates  of  shallow  subsurface  leaks  and  liquid  bodies,  locating  mine shafts  and  voids,  mapping  the  extent  of  aquifers,  aquifer  contamination  evaluations,  and archaeological studies. NGE-TFT has successfully used ER to gather resistivity data to be used for the  design in  grounding  systems  for  electrical  substations  and  cell  towers. We  also  employ  the soil  box  resistivity  test  as  a  laboratory  analysis  of  the  resistivity  of  soil  samples  from  the  field. This  method  is  mainly  used  to  determine  the  potential  for  corrosion  of  pipes  and  other metals buried in the tested soils. Electrical  Resistivity  is  limited  to  summer  use  and  should  be  employed  in  soils  that  are unsaturated with rain water. Generally, a brief site assessment should be conducted prior to the commissioning  of  an  ER  survey  to  evaluate  the  site  conditions  and  determine  if  ER  technology may  be  a  suitable  exploration/inspection  method  for  a  given  project.  New  and/or  unproven applications for Electrical Resistivity are constantly being discovered and tested, so contact NGE-TFT and let us work together to determine if ER is a suitable technology for your next project!