Prior to 2009, ASTM F855, Standard Specifications for Temporary Protective Grounds to Be Used on De-energized Electric Power Lines and Equipment only included one table indicating the specifics to which ground set designs were to be tested. This “Table 1” was based on a near symmetrical current, limiting the circuit inductive reactance to resistance (X/R) ratio to a maximum of approximately 1.8 (20% asymmetry).
When overhead electrical line workers employ proper personal protective grounding practices they are usually protected from electrical hazards that might arise from working on de-energized lines and equipment. But, what about workers at ground level? How are they protected, and from what kinds of situations are they protecting? The answer is from hazardous differences in step and touch potentials.