Electrical Capacity Assessments for EV Charging

A capacity assessment establishes how much spare electrical capacity a site has, and therefore how many EV chargers it can support — before deciding whether any supply or distribution board upgrade is needed.

What it involves

• Determining the incoming supply rating and the site's existing maximum demand.
• Measuring or profiling actual usage over a representative period, applying diversity.
• Calculating the headroom available for EV charging.
• Considering how load management can stretch that headroom across more chargers.

Why it matters

Installing chargers without a capacity assessment risks either overloading the supply or over-specifying an expensive upgrade that is not needed. The assessment turns guesswork into a clear plan: how many chargers, at what power, and whether an upgrade or load management is the better investment.

The first step

A capacity assessment is normally part of the EV site survey. It gives duty holders the facts to make a sensible, future-proofed decision about their charging infrastructure.