How many workplace EV chargers can our existing electrical supply support?

The useful figure is the spare capacity available during the site’s busiest period, not simply the rating of the incoming supply. A workplace may support several chargers when vehicles charge at different times or power is managed. The same supply may support fewer chargers if they all draw full power together.

We calculate that capacity from the building’s electrical characteristics and its real operating pattern. This gives you a practical charger plan rather than a count based only on the number of parking spaces.

What we check before calculating the charger count

• Incoming supply: We check the supply arrangement, available phases, service equipment and the capacity available to the premises.
• Existing demand: We assess the electricity used by lighting, heating, machinery, refrigeration, IT equipment and other significant loads.
• Peak demand: Your quietest period may leave ample headroom, while a busy production period may leave very little. We use the period when the site is most likely to draw power, not an average day.
• Distribution equipment: We inspect the main switchgear, distribution boards, protective devices and cable routes. An incoming supply can have spare capacity while the existing distribution board cannot safely accommodate new circuits.
• Charger demand: We consider the charging power needed at each parking space and how long vehicles normally remain on site.
• Future demand: If you expect more electric vehicles, additional staff charging or an electric van fleet, we include that in the design rather than filling all available capacity on the first installation.

The number of sockets is not always the number of vehicles charging at full power

A charger may be available to a vehicle without drawing its maximum power continuously. The vehicle controls its own charging, and the charging system can distribute available power between connected vehicles.

For example, a workplace with a long employee parking period may have enough time to charge several vehicles in sequence. A depot where vehicles return together and need rapid turnaround has a different electrical requirement. We base the design on arrival times, departure times, vehicle battery sizes and the charge each vehicle needs.

This distinction matters when comparing a bank of chargers with a smaller number of high-use charging points. The right arrangement depends on how the vehicles are used, not just how many spaces are available.

How load management increases the usable capacity

Load management reduces or shares charger output when the building’s other electrical demand rises. If the site is using more power for heating or machinery, the charging system can reduce charging temporarily. When that demand falls, more power becomes available for the vehicles.

We can design the system to limit the combined charger load or to respond to the site’s total electrical demand. This can allow more charge points to operate from an existing supply than would be possible if every unit started at full power together. It does not create extra electricity capacity, so we still check the supply, cables and protective equipment first.

Load management also needs a clear operating strategy. A site may prioritise pool cars, assign power equally, charge vehicles according to departure time or give priority to a fleet that must leave first. We discuss that pattern before selecting the control arrangement.

When the existing supply is not sufficient

An unsuitable result does not always mean that the project has to stop. We may be able to:

• reduce the charging power at individual points;
• use managed charging so the building and chargers share the available capacity;
• install fewer charge points initially, while leaving the distribution equipment ready for expansion;
• schedule charging outside the site’s highest-demand periods; or
• apply to the local network operator for a supply upgrade where the site genuinely needs more capacity.

A supply upgrade can involve external equipment, changes to the service connection and additional design work. We identify that requirement before installation so it does not appear as an unexpected problem during the work. If the site has on-site generation or battery storage, we assess how it can contribute to the charging plan, but we do not assume that it will cover all charging demand.

Why a three-phase supply can change the design

Some workplaces have a single-phase supply, while others have a three-phase arrangement. This affects how the charger load can be distributed and how much power the site can use without placing excessive demand on one part of the installation.

We check phase balance as well as total capacity. Adding chargers without considering that balance can create problems even where the overall supply appears adequate. The charger layout, cable routes and distribution equipment all need to match the supply arrangement.

What the assessment gives you

We turn the electrical survey and usage information into a charging design. The resulting recommendation sets out the number of charge points, their charging power, any load management, the required electrical alterations and the likely route for future expansion.

If the workplace has an older installation, we also explain any work needed before the chargers can be connected. That may include improvements to distribution equipment, protective devices, earthing or cable routes. We separate essential electrical work from optional future provision, so you can see what the current installation requires and what can wait.

Our electrical team designs and installs the work to the requirements of the site rather than treating every parking area as the same. NICEIC and ECA registration means the electrical work is assessed against the relevant standards, with certification and installation information provided for the completed system.

The final charger count should therefore reflect three things: the capacity the site can safely provide, the charging demand your vehicles create and the amount of expansion you want to support. A site survey and a proper load calculation are the reliable way to establish that balance.