The Fluke EI-162AC Clip-On Current Transformer (Inducing) is used with Models 1623 and 1625 to perform selective and stakeless testing. Selective testing involves using one clamp, along with earth ground stakes to provide earth ground loop resistance values for one earth ground electrode. Stakeless testing uses two clamps to perform earth ground loop resistance measurementa without stakes. Both tests have the advantage of providing measurements without disconnecting from the grounding system, which is safer and quicker.