Usually, the AC loss from the superconducting element of an SFCL due to the load current is very small because it is composed of the combination of bifilar windings with very small reactance. Although the AC loss is small enough, we should be albe to predict for the design and control of the cryogenic system. In fact, an SFCL for the transmission voltage class may not generate ignorable AC loss because of the inevitable space between the HTS wires for the high voltage insulation and cryogenic efficiency. To measure the AC loss dependency on the space between the 2G HTS wires with the width of 4.4 mm, we prepared an experimental setup which could adjust the distance between the wires. We used two 500-mm length HTS wires in parallel and applied the current in the opposite direction for each wire to simulate a part of a current limiting module for a high voltage SFCL. We also put two couples of voltage taps at the ends of each wire and a cancel coil in the voltage measurement circuit to compensate the reactive component from the voltage taps. In this condition, we varied the distance between the wires to investigate the change of the transport current loss. A similar experimental study with HTS wire with the width of 12 mm is now in progress.