Your electrician has likely never seen or tested this unit and is referring to older capacitor based systems that are not digital in nature. The Power Perfect Box Wire-In does not use oil filled capacitors but rather harmonic rectifiers developed by NASA to filter electricity, improve efficiency and protect electronics on the space shuttle. This technology has been adapted to create a modern energy management system that can regulate voltage, filter out potential negative harmonics and provide phase correction, making your electricity more efficient. Greater efficiency and less electrical consumption usually results in cost savings.