This is very important with regards to electrical potential difference in order to avoid sparkles that can ignite gas etc.in socalled Ex-areas. The machine sends a stream up to 45 Ampere through the test object (ladder/tray or supports) and measures the voltage drop between two designated points. Then the resistance is measured automatically in Ohm.
The picture below is from February 2013 where DNV visited our Test Center in order to certify that our conductivity testing complies with the IEC 61537 standard. To the right is Hans Arne Bjelland who is Oglaend System’s Test & Automation Engineer and to the left senior surveyor from DNV, Stein Erik Jørstad.