Above ground indirect inspection techniques have evolved so rapidly that some of their underlying concepts have almost been forgotten. In fact there seems to be some ambiguities currently concerning the functionalities and utility of each survey type. In this paper we undertake a quick review of coating condition surveys namely AC and DC voltage gradient survey exploring their founding concepts and their evolution over the last few decades. We also address some supposed limitations of these surveys – such as data acquisition of voltage gradient surveys over paved surfaces – and show that it is possible to acquire usable data in such circumstances and correlate them carefully to evaluate the pipeline coating condition. Finally we address some on-going technical issues that require more industry collaborative research to advance the utility of voltage gradient surveys