What is the best voltage for the customer?

The best voltage for the customer is the lowest voltage at which all electrical equipment, appliances and devices operate correctly and efficiently, offers the lowest operating cost and provides the longest life. This voltage is usually obtained when the service voltage is at the lowest ANSI C 84.1or CAN-3-C235-83 allowable voltage. We recommend that end-of-line voltages be controlled as close to Vac (Minimum Allowable Service Voltage + Estimated Transformer Voltage Drop) to hold service voltages to a minimum. ANSI minimum is 114. Vac and CAN minimum is 110 Vac for single-phase systems and 112 Vac for three phase systems. (Note for the purposes of this discussion all voltages are on a 120 volt base.)

Most motors are nameplate rated at voltages below the nominal system voltage. For example most motors designed to run on a nominal 120 Vac are actually rated to operate at 115 Vac. Furthermore, the motor manufacturers design their motors to operate within a range of voltages usually 5% below to 5% above the nameplate rating.

Tests for different motor applications have shown the following:

• For freezer applications, average kWh per day drops when voltage is reduced. This indicates that there is an efficiency increase in kWh per degree setting because the freezer process is essentially a closed loop cooling process.
• Central AC units become more efficient as voltage is reduced until voltage reaches almost 8% below the compressor motor nameplate rating.
• Pool Pump tests in California show reduced kW and increased PF for voltages down to approximately 8% below nameplate.

Additionally:

• Most new electronic ballast fluorescent and HID lighting become more efficient as voltage is reduced to as much as 7% below nominal voltage.
• Incandescent lamp life and other heating element life increases with lower voltages.
• When operating at the lower voltages there is no noticeable drop in overall lighting levels.