How should you prepare ducting for more EV chargers?

Plan future charging positions and cable routes before resurfacing, but have a designer specify duct size, depth and access points for your site. HSE identifies 3 excavation safety elements: planning, locating services and safe excavation [S1]. Empty ducting is useful only when cables can be installed and the electrical design can support the intended expansion. Checked October 2026.

Last checked 17 October 2026

Should you install ducting before the car park is resurfaced?

Request an expansion design while the site team can still change the civil works. Mark the first charging bays and potential later bays on the same plan. Compare a route serving only the first stage with a route that reaches the later positions. Ask the designer to show what each option actually enables.

In England, the Approved Document S FAQ says cable routes should be as straight as possible, with suitable access points so cables can be pulled through later [S3]. Use that as a design question even when your project is a voluntary retrofit: can the proposed cable be installed without reopening the finished surface?

Do not buy an unspecified “future-ready” allowance. Request a drawing, installation detail and handover evidence. Read groundworks and cable runs alongside the site survey guide.

Where should future chargers and cable routes end?

Work backwards from the later parking layout. Identify the vehicle position, charger location, usable access space and maintenance route. Check whether the expansion would displace ordinary parking, deliveries or an accessible route. Have the site manager review that drawing before the civil contractor prices it.

The Approved Document S FAQ requires the future connection location to be suitable for a compliant charger [S3]. An endpoint beside existing furniture is therefore a question for the designer, not proof that the route is useful. Show the equipment footprint and the intended cable entry on the drawing.

Compare the plan with EV bay dimensions. Keep spare routes accessible after landscaping and later building work. Agree who can authorise changes where the charger layout and civil drawing conflict, so the contractor does not resolve the issue by moving the endpoint informally.

What duct size, burial depth and access points should you specify?

Ask the electrical designer and civil designer to issue the installation detail together. It should identify the intended cable, duct dimensions, route, bends, access points, protection and interfaces with other services. Get the selected cable’s pulling limits and the proposed installation method checked before construction.

This guide does not supply a universal diameter or burial depth. Those figures need a design appropriate to your loads, ground and risk of damage. Ask the contractor to identify any network-owner requirements where the route will interface with network assets.

Use the following schedule to make quotations comparable. These are requested deliverables, not technical limits.

Ask the designer to state what remains undecided. If the future charger type is unknown, record the expansion envelope the design supports rather than implying it will accommodate any equipment.

How should you plan excavations and identify buried services?

HSE describes planning, locating and identifying services, and safe excavation as the main elements of a safe system of work [S1]. Commission that work before the contractor opens the surface. Set aside time to investigate uncertain service positions rather than relying on an allowance in a quotation.

HSE says underground cables must be located, identified and marked before work, using suitable locating equipment and competent people [S2]. Give the contractor available records, but require a method that accounts for their limitations. Keep the survey and excavation decisions with the job records.

Have the contractor assess trench stability, support, water and the safety of people near the excavation [S5]. Agree barriers and a temporary customer route with your site manager. Plan how works interact with emergency access, deliveries and the business’s opening hours. This is contractor-planning information, not DIY digging instructions.

Does the electrical design support later charger expansion?

Ask for a staged load schedule, not just spare holes in the ground. Kilowatts (kW) measure power; kilowatt-hours (kWh) measure energy. As an assumed arithmetic example, 6 chargers rated 7 kW total 42 kW of nameplate demand. That sum does not establish the available supply or the power drivers will receive under load management.

Have your designer compare simultaneous charging with the site’s other loads. Ask whether expansion needs a different board, feeder cable, control system or network connection. Discuss connection requirements with your distribution network operator (DNO), the local electricity network company. Keep those decisions separate from acceptance of the duct route.

Review load management versus an upgrade. Request the operating limits and assumptions in writing. Do not approve a claim that a spare route reserves electrical capacity for you.

What building rules and cost comparisons should your brief include?

Approved Document S concerns specified building work in England, including new non-residential buildings and major renovations [S4]. Ask building control to confirm scope and required provision. For another UK nation, have the designer confirm that nation’s requirements rather than applying the English document automatically.

Obtain separate prices for the initial works, spare routes, future cable installation and any later connection work. Compare them with the cost of reopening and reinstating the surface if expansion happens. Treat future costs and likelihood of expansion as assumptions; there is no universal percentage saving from spare ducting.

What should you do next?

Collect your resurfacing schedule, utility records and staged parking plan, then get matched with an installer that covers your area.

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