AROUND THE CIRCUIT

Do 240 Volts appliances use less energy than 120 Volts appliances?

Do 240 volts appliances use less energy than 120 volts appliances? From time to time I have been asked this question by people who are looking for ways to reduce their electricity consumption. The answer to this question is - not really. If that was really the case then people would have been advised to use 240 volts appliances as part of the energy conservation tips that are occasionally broadcasted to the public.

Ironically, the misconception that 240 volts appliances use less energy than those operated at 120 volts is peddled mostly by some electricians. Strangely, these electricians do not understand the relationships between voltage, current, power and energy. A 240 volts appliance would basically use half as much current than a 120 volts appliance rated at the same power. That is why these electricians believe that 240 appliances use less energy. But using less current does not necessarily mean less energy is consumed. The relationship between voltage, current and power is explained in simple terms below.

Current is the flow of electrically charged carriers, usually electrons, in a circuit. It is measured in Amperes.

Voltage, also called electromotive force, is the potential difference in charge between two points. It is the force that drives current in a circuit, and is measured in Volts.

Power, measured in Watts, is the rate of doing work or producing or expending energy.

Essentially, ignoring other things such as power factor, voltage multiplied by current equals power. The equations below show that a 480 watts appliance rated at 240 volts will operate at 2 amperes, and if rated 120 volts will operate at 4 amperes for the same 480 watts:

1. 480 watts = 240 volts x 2 amperes
2. 480 watts = 120 volts x 4 amperes

So your 240 volts appliance will use half as much current as your 120V appliance at the same wattage. So how does this affect the energy consumed?

The energy consumed by an appliance is based on the operating wattage and the length of time it is operated. Therefore, a 240 volts lamp rated at 40 watts will consume the same amount of energy as a 120 volts lamp also rated at 40 watts if both are operated for the same length of time. The electricity companies measure your energy consumption in watt-hours (or kilowatt-hours, meaning 1000 watt-hours). The watts of the appliance multiplied by hours in use give the watt-hour (energy) consumption. So, irrespective of the voltage rating, the energy consumption of an appliance will be based on its wattage and the length of time it is operated.

Share this article with anyone who tells you that 240 volts appliances use less energy than 120 voltage appliances.