Can our existing electrical supply support commercial EV chargers?

The key question is how much capacity remains after the building’s normal demand is taken into account. We look at the incoming service, the distribution equipment and the way the chargers will be used. That shows whether the site can accept the proposed charging load as it stands, or needs a controlled charging strategy or network work.

A charger’s advertised output is only part of the calculation. Several chargers operating together can create a much larger demand than one unit. We consider the number of charge points, their maximum output, likely arrival and departure patterns, and whether other vehicles could charge at the same time.

Your building may also have high demand from heating, refrigeration, machinery, lifts, ventilation, lighting or workshop equipment. We allow for those loads at the times when charging is most likely. A supply that looks adequate during a quiet period may not have enough headroom during a busy working day.

We start by examining the supply into the premises. This normally includes:

• the incoming service capacity and supply arrangement;
• the main cut-out, switchgear and metering;
• whether the site has a single-phase or three-phase supply;
• the main distribution board and available ways for new circuits;
• the size and route of existing cables;
• earthing and bonding arrangements;
• protection, fault levels and voltage drop; and
• the condition and capacity of equipment that the new installation would rely on.

We then compare that information with the proposed charger arrangement. A single lower-power AC charger may place a modest load on a building. Multiple faster chargers, or high-power DC equipment, can require a much larger connection and different distribution equipment. The proposed charging pattern matters as much as the number of sockets.

Measured demand can be more useful than a reading taken during one visit. Where the site’s usage is variable, we may need information from energy bills, a building management system or a period of load monitoring. This helps us see the highest demand and the spare capacity available at different times. We can then base the design on how the premises actually operates rather than on an assumption.

Load management can make better use of a limited supply. A dynamic system measures the building’s demand and adjusts vehicle charging around it. It can reduce charging output when other equipment is running, then allow more power when the building load falls. Some sites may also use scheduled charging or divide available power between several charge points.

That approach does not create extra electricity capacity. It controls when and how quickly vehicles charge. We therefore discuss the operational effect with you. If vehicles must all be ready at a particular time, the available charging power may need to be higher than it would be for vehicles that remain on site for longer.

Three-phase power is not automatically available because the site is commercial. Some premises have a single-phase supply, while others have three phases but limited spare capacity on one or more of them. We check phase loading and distribute the circuits correctly. If the incoming supply is unsuitable, we explain the implications before any installation work begins.

Where the proposed demand exceeds the available capacity, there are several possible routes:

• install fewer chargers initially;
• choose a lower charging output where it meets the vehicles’ needs;
• use managed or scheduled charging;
• upgrade the site’s consumer unit, distribution board, cabling or protective equipment;
• apply to the local distribution network operator for a supply or connection upgrade; or
• plan the installation in stages, allowing for future vehicles and chargers.

The distribution network operator decides whether the wider network can provide the requested capacity. Its assessment may involve the service cable, local network equipment and the connection point. An upgrade can affect both the project cost and the work programme, so we identify that possibility early rather than treating it as an unexpected issue during installation.

Some rural and older commercial properties have long private supplies, outbuildings fed from smaller distribution boards or connections designed for a different type of use. Farms, workshops and converted buildings can also have several separate supplies or unusual cable routes. We trace how the premises is arranged before deciding that a charger can connect to an existing board.

The site survey also covers the route from the distribution equipment to the charge points. A long cable run may require larger conductors to control voltage drop. External routes may need additional mechanical protection, and the equipment must be positioned where vehicles can use it without creating a trip or impact risk. We include these details in the design instead of assessing capacity in isolation.

For a landlord, property manager or business owner, the result is a clear choice between the available options. The quotation can set out the proposed charger load, any load management, distribution work, network application and likely future provision. We provide the quotation before work starts, so the cost of the chosen route is clear rather than added as a surprise.

Electrical work is carried out by our directly employed team, with the installation designed and tested to the requirements that apply to commercial charging equipment. As a NICEIC- and ECA-accredited electrical contractor, we can provide the inspection, testing and certification needed for the completed work. We also explain the controls to the people responsible for the site, so they understand how charging is allocated when the building is busy.

If the supply cannot support every charger at full output, that does not necessarily end the project. It means the charging demand, site operation and available electrical capacity need to be designed together. We set out what the existing supply can support, what would need upgrading and what users should expect from each option.