Ask the Expert: Upgrading the electrical supply

Whether you’re navigating complex installations, troubleshooting challenging systems, or looking for guidance on the latest industry standards and technologies, Darren Staniforth, Head of Electrotechnical Solutions at CEF, is here to help.

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Question:

Should we be upgrading the electrical supply when installing renewable technology installations?

Answer:

When installing renewable technologies, it’s critical to assess and potentially upgrade the existing electrical supply. Many domestic and small commercial installations still operate on a 60A or 80A single-phase supply, which may be insufficient when integrating high-demand technologies. For example, a typical EV charger can draw 32A continuously, and a heat pump may require a similar load. When combined with existing household or business loads, this can exceed the capacity of the main cut-out fuse, leading to thermal damage to supply tails and distribution equipment.

Installers should carry out a detailed load assessment, factoring in diversity where possible. Where the calculated maximum demand approaches or exceeds the supply rating, an upgrade to a 100A supply – or even a three-phase supply in some cases – should be considered.

Recently I spoke with Mark Coles, Head of Technical Regulations at the IET, about diversity and the challenges designers have when calculating new systems. Mark was keen to point out the current diversity tables date back to the early part of the last century.

Mark had been meeting with the Energy Networks Association to try and resolve this issue. Where possible an upgrade to 100A is going to be allowed, however, it may not be possible for everyone. In this situation Mark discussed the need to employ additional technology to curtail the loads where possible, to keep the whole installation load lower than the supply fuse in the service cut-out. Mark also encouraged installers to source new technologies from the same supplier to ensure different parts of the system communicate seamlessly to offer the best possible management of loads.

I believe we’ll see manufacturers open their operating systems to allow open communication across renewable technologies, ensuring we can manage the load profiles to work within the existing supply size.

In summary, upgrading the electrical supply is not just a matter of capacity – it’s a fundamental part of ensuring a safe, compliant and future-ready renewable installation. However, we can’t assume an upgrade is always possible and need to look for other ways to work with the existing electrical supply.

cef.co.uk

Need some technical advice? Darren is here to help! Send your questions to info@electrotechnicalnews.com

This article appeared in Electrotechnical News July/August 2025 edition – read it here