CIS or close interval survey, internationally more commonly referred to as CIPS (close interval potential survey), is a common means of validating the proper performance of a cathodic protection system along long length pipelines or within stations/plant piping networks. The survey consists of taking potential readings as the crew walks over the center of the buried pipeline. We usually take these readings while cycling on and off all influencing current sources at a regular intervals. Thus, readings capture the potential between the pipe and a reference electrode. We capture both the current on and current off cycle readings. This process repeats over the entire length of the pipeline. We then analyze the on/off data to confirm the CP system is working properly and achieving the required system polarization.