Currently, power distribution companies have several problems that are related to energy losses. For
example, the energy used might not be billed due to illegal manipulation or a breakdown in the customer’s
measurement equipment. These types of losses are called non-technical losses (NTLs), and these
losses are usually greater than the losses that are due to the distribution infrastructure (technical losses).
Traditionally, a large number of studies have used data mining to detect NTLs, but to the best of our
knowledge, there are no studies that involve the use of a Knowledge-Based System (KBS) that is created
based on the knowledge and expertise of the inspectors. In the present study, a KBS was built that is
based on the knowledge and expertise of the inspectors and that uses text mining, neural networks,
and statistical techniques for the detection of NTLs. Text mining, neural networks, and statistical techniques
were used to extract information from samples, and this information was translated into rules,
which were joined to the rules that were generated by the knowledge of the inspectors. This system
was tested with real samples that were extracted from Endesa databases. Endesa is one of the most
important distribution companies in Spain, and it plays an important role in international markets in
both Europe and South America, having more than 73 million customers
