Getting Down to Earth 5SafetyThere is an inherent safety problem in earth resistance testing that requires care and planning by the user of the test set. The possibility exists that a fault in the power system will cause a high current to flow into the ground system while the test is in progress. This may cause unexpected high voltages to appear at the current and voltage probes and also at the terminals of the test set. This risk must be evaluated by the person responsible for the tests, taking into account the fault current available and expected step-and-touch potentials. IEEE Standard 80 entitled “IEEE Guide for Safety in AC Substation Grounding” fully covers this subject. (Other standards may prevail elsewhere in the world.)We recommend that the operator wear rubber protective gloves (ANSI/ASTM D120 or equal) while handling connections and use a rubber safety mat (ANSI/ASTM D178 or equal) while operating the test set.
