Voltage Optimisation Explained

There is a legal requirement for the National Grid to maintain the UK mains voltage that is delivered to our homes and businesses – most of us know this as 240V.

This is known as the “statutory supply voltage” and in actual fact, in the UK, it is set at between 216V and 253V: The average voltage supply being around 242V.

The reason for the “statutory supply” being in a fairly wide range is because of increased electricity demands at different times of the day or simply the amount of power being used at any one time will cause the grid voltage to fluctuate.

Fortunately, for UK  consumers, the supply voltages in the European Union have been much lower than ours and steps were taken in 1995 to harmonise supply voltages across all of the European Union, resulting in a requirement that all electrical equipment supplied within the European Union (CE mark) must work at voltages as low as 207V.

So, in the UK, where supply voltages are traditionally much higher, equipment made for the European Union (which will work quite comfortably at 207V), is oversupplied with significantly higher voltages than it is designed to take and this leads to higher running costs, unnecessary energy consumption and a shortened lifespan.

By adopting voltage optimisation, your electricity will be supplied at a sensible voltage of around 220V.

Whilst there are many competing energy saving products on the market, they all involve replacement of perfectly good working items that will end up being land filled (old lighting, air-con units, motors or drives etc.). If you are serious about your environment then voltage optimisation should be your first step, as this addresses your entire business “holistically”, then, when lighting and drives fail, you should replace them on a case by case basis.

As an example, if you are ISO14001 accredited, efficient waste management is one of the requirements; voltage optimisation will help you to meet those requirements.

The maths behind Ohms Law and why Voltage Optimisation works

The maths behind Voltage Optimisation relies on Ohms Law, which you might remember from school – if you want to check you can find the Ohms Law Calculator here.

Basically the formula for Power is as follows:

            Power = V2 ÷ Z

Where V (248V) is the supplied voltage and Z (10 Ω) is the resistance or load, then the power in Watts would be 6.15kW.

By reducing the voltage to 220V (11% reduction) but maintaining the same resistance, the consumption would be 4.84kW, a reduction of 22% in power consumption.

Based on this voltage optimisation works on the basis that some, but not all, equipment will save twice as much energy for every 1% reduction in voltage.



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