This thesis presents a method of compare the reducing high voltage source more than necessary to the pilot study two plants in case of load near power station the same distance but different. There are 2 methods first method reducing the voltage by adjusting tap transformer. Other method installed by voltage equipment. Regulator in a factory used 2 methods for measured the value of voltage before&after and continued to reduce the voltage until minimum loading that this factory can normal operate. From two trials we found that reducing the voltage by installation voltage regulator/voltage equipment can save more energy cost 10.23% than adjusting tap transformer that can save only 4.66%. And analysis of Specific Energy Consumption (SEC) by reducing the voltage level of the industry. Energy consumption kWh per 1 output (plastic bottles) Then lower from 0.119 kWh per 1 bottle remaining 0.089 kWh per 1 bottle This is in line with the energy analysis that main control electric power.