Energy network operators have launched a consultation to gather views on changing the lower limit of the voltage standard across distribution networks, currently set at 216 Volts.  

Notably, current voltage limits in Britain were set conservatively high to ensure that even the most remote end-of-line customers received adequate supply. Now we are seeing how the result of connecting more and more domestic low-carbon generation to the distribution network is causing a rise in the operational voltage, leading to increasing issues with ‘overvoltage’ tripping of low-carbon technology (LCT) devices, such as electric vehicle (EV) chargers.   

With some analysts predicting the number of EVs on the UK’s roads rising by 72% over the next three years, it is essential to get this right.  

In the wider world, voltage reform – modernising standards, introducing smarter operating envelopes and unlocking more dynamic network management – is quietly becoming one of the most important enablers of the UK’s future energy network, and ensuring the access of customers to affordable energy supplies.  

Through our ‘Engineering for the Future’ initiative, ENA are specifically seeking a review of the lower limit, currently set at 216 Volts, to 207 Volts. This 4% reduction in range limits would align network voltage tolerances with Europe and provide a greater amount of operational ‘legroom’, allowing even more low-carbon generation to connect to the grid.  

These changes would support networks in meeting the predicted rise in electricity demand and help ensure the UK can access the clean, affordable and resilient energy it needs in the future. Dovetailing with the historic levels of investment in transforming the grid that both distribution and transmission network operators will make over the coming years, we must retain our focus on common sense and practical reforms.  

ENA are specifically seeking a review of the lower limit, currently set at 216 Volts, to 207 Volts. This 4% reduction in range limits would align network voltage tolerances with Europe and provide a greater amount of operational ‘legroom’, allowing even more low-carbon generation to connect to the grid.  

Beyond changing the voltage limits, voltage reform would allow networks to operate within intelligent, adaptive voltage envelopes rather than rigid, worst-case boundaries more suited to a 20^th century context. 

Smarter voltage control, enabled by real-time data and coordinated transformer tap operations (used for maintaining voltage stability in distribution networks), can maintain a safe and reliable network, whilst meeting the regulatory standards.  

Equally, by employing a lower voltage limit and enabling smarter voltage measurement, more dynamic transformer control and more transparent export flexibility arrangements, households and community-scale generators could more easily be installed and connected.  

Rigorous consultation 

A change to the voltage limits is not a quick process; ENA would need to fully consult with network operators, customers and experts, to ensure any reform to the technical regulation governing voltage limits is safe, seamless and effective. This rigorous consultation is essential to ensuring an effective process.  

Looking ahead to later this year, ENA will be focused on how the change impacts everyone connected to the network. There may be impacts on demand or generation customers that need to be fully worked through and understood. We shall be consulting and working with those stakeholders in the coming months before working with the government and regulator, to push for a change in legislation and a revision of operational standards.  

In the conversation around voltage reform and changing voltage limits, there is occasionally reference to the savings that may result to consumers from lower voltage limits. Ensuring best value for customers is our key focus but at this stage it is impossible to commit to a direct cost saving until the consultation is complete.   

What network operators can say is that any voltage reform process – particularly if aligned with the wider work to modernise engineering standards and frameworks – would be focused on ensuring that networks can deliver the most cost effective, reliable and customer focused service possible.

The views and opinions expressed in this article are strictly those of the author only and are not necessarily given or endorsed by or on behalf of the Energy Institute. 

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