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Electrical Infrastructure

Everything between the network operator's connection point and the bays - substation or supply position, switchgear, distribution, protection, metering, cable and the containment that carries it, plus the comms that make the site controllable.

Last updated 2026-09-06

Typical duration

Typically 3-8 weeks of installation on a mid-sized scheme, though switchgear lead times and the network operator's outage and witnessing dates usually set the critical path rather than the labour on site.

What is Electrical Infrastructure?

The chargers are the visible part of a charging scheme. This stage is the part that costs the money and carries the risk. Between the point where the distribution network operator hands over power and the point where a driver plugs in sits a chain of equipment: an incoming supply position or a new customer substation, switchgear, distribution boards or feeder pillars, protection, metering, and the cabling that runs out to every bay. On a small workplace scheme that chain is a board and a few circuits. On a rapid charging hub it is a substation, a private low voltage network and a great deal of cable in a great many ducts, all of it installed in the gap between the civils finishing and the units arriving.

Responsibility is split, and the split is the first thing to establish. The distribution network operator builds and owns up to the connection point; the client owns everything beyond it. That boundary is electrical, legal and commercial at the same time, and it decides who designs what, who inspects what, who is allowed to work where and who carries the risk if something is not to the operator's satisfaction. Where the operator will adopt part of the installation, that part is built to its requirements and inspected on its terms, on its dates, by its people. The project works to the operator's calendar rather than its own, and a missed witness or outage slot costs more programme than a month of bad weather.

Nothing about the arrangement is decided on site. Cable sizes, protection settings, the earthing arrangement, segregation, clearances and the tests that have to be passed all come from the designer and from the distribution network operator, and site's job is to install exactly what has been issued and to prove that it did. Alongside the power runs a second, quieter installation that is just as capable of stopping handover: the data. Every unit needs a communications path back to the client's operator, the load management system needs to see and control every circuit, and the metering has to report accurately to whoever is billing. That cabling, and the connectivity behind it, gets designed and installed at this stage rather than being improvised in the last week.

Compare the methods at a glance

Method comparison graphic coming soon

When and why is Electrical Infrastructure used?

This stage starts as soon as the ducts are proved and the plant bases are cured, and it overlaps heavily with the charger installation that follows - cable is usually pulled and terminated at the board end while the units are still being delivered. It sits here because cable needs somewhere to run and switchgear needs something to stand on, and it has to be substantially complete before energisation because the distribution network operator will not close its connection onto an installation that has not been built, tested and documented to its satisfaction. The reason it is front-loaded is that this is where the long-lead items live. Switchgear, transformers and anything the operator has to manufacture are ordered against the energisation date, and a delay to any of them cannot be recovered by adding labour. The sequence within the stage is fixed by safety rather than preference: routes and earthing are proved before anything is covered, dead testing is completed before anything is energised, and settings are applied from the approved schedule and independently checked before the installation is asked to protect itself. Get the records right as you go and commissioning becomes a formality. Leave them until the end and the site spends the week before energisation retesting work it has already done, with no float left to do it in.

Types of Electrical Infrastructure

Explore each method in depth - benefits, limitations, plant and quality control on its own page.

New customer substation with a private low voltage network

The full arrangement for a high-power hub: a substation at the connection point, a private distribution network out to the bays, and metering at the boundary. It gives the capacity a rapid site needs and full control over the distribution, at the cost of the longest lead time, a plant compound to accommodate and a much larger interface with the network operator.

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New or upgraded supply into existing infrastructure

A new or uprated network connection feeding a dedicated board that serves the chargers, alongside whatever else the site already runs. Common on retail and workplace sites, simpler than a substation, but the existing installation has to be assessed honestly because the scheme inherits its condition and its spare ways.

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Feeder pillar and distribution board schemes

Smaller sites fed from spare capacity in the existing supply, distributed through a feeder pillar or a dedicated board with a circuit per unit. Quick, cheap and easy to extend, and by far the most common arrangement in car parks and on-street schemes, but it depends entirely on the headroom that was measured at the survey stage being real.

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Load-managed distribution with storage or generation support

Distribution designed around a control system that shares the available capacity between the units in use, often with on-site storage or solar behind the connection. It gets a busy site working on a modest supply, at the price of a control interface that has to be designed, installed and proved as carefully as the power side.

Explore this method

Best suited for

  • Rapid and ultra-rapid hubs needing a dedicated substation and a private distribution network
  • Retail, workplace and leisure sites adding a dedicated board to an existing supply
  • Depot and fleet schemes with many units on one site and a managed overnight load
  • Capacity-limited sites where load management is the design rather than an add-on
  • Phased schemes where the distribution is built once with capacity for later units

Electrical Infrastructure: step by step

  1. 1

    Step 1: Confirm the boundary and what each party is building

    Before anything is installed, the interface with the distribution network operator is confirmed in writing: where the point of connection physically is, what the operator will build, what the client is expected to build, what the operator will adopt, what it will inspect and witness, what metering it requires and what evidence it wants before it will energise. Access arrangements to the operator's plant are agreed, along with the dates for any outage, witness or inspection. Those dates are then treated as fixed and everything else is arranged around them. Experienced teams keep the operator engaged from the design stage onwards rather than presenting it with a finished installation, because this is the stage where an assumption made six months earlier surfaces, and it always surfaces at the worst possible moment.

  2. 2

    Step 2: Set the substation, switchgear and distribution equipment

    The heavy items are delivered and set on the bases prepared during the civils, using proper lift planning even though the loads are modest by construction standards, because the equipment is expensive and the compound is usually tight. Position and orientation come from the design and from the equipment itself - cable entries, door swings, ventilation and the space needed to work on the front of a panel are all fixed and none of them can be adjusted afterwards. Units are levelled, fixed down as the design requires and bonded to the earthing system. Equipment that will stand for weeks before it is energised is protected against moisture and vermin in the way the manufacturer specifies, which on a part-built outdoor compound is a real risk rather than a theoretical one.

  3. 3

    Step 3: Complete the earthing and bonding

    The earthing installation is completed to the arrangement the designer has specified and connected to everything the design identifies - the substation or supply position, the switchgear, the distribution equipment, the plant compound and, in due course, every charging unit. The arrangement itself is a design decision that depends on the type of connection, the site and the equipment, and it is one of the few things on a charging site where getting it wrong is dangerous rather than merely inconvenient. Connections are made using the specified method, protected against corrosion and left accessible where the design says they must be testable. Everything is inspected, tested and recorded formally, and any later alteration is recorded on the as-built, because that drawing is what the operator will rely on for the life of the site.

  4. 4

    Step 4: Pull and terminate the main cable runs

    The main cabling between the connection point, the switchgear and the distribution equipment is pulled through the ducts laid during the civils. Drums are set up so cable is pulled at the right radius and without dragging, rollers and winches are used where the pull is long, and the manufacturer's tension and bend limits are respected - a cable damaged inside its insulation gives no outward sign and fails in service months later, by which time the bays are trading and digging it up is a very different proposition. Cable is supported, cleated, segregated and labelled as the design requires. Terminations are made by qualified people to the specified method, tightened with calibrated tooling and recorded as they are completed rather than from memory afterwards.

  5. 5

    Step 5: Install the final circuits out to the bays

    A circuit is run to each charging position along the duct routes, terminated at the board end and left coiled, protected and clearly identified at the base end ready for the units to arrive. Identification matters more here than anywhere else on the job, because a hub can have dozens of near-identical circuits emerging from near-identical duct stubs, and a mislabelled circuit is the kind of error that surfaces at commissioning and takes days to unpick. Circuits are labelled at both ends, recorded on a schedule and left in a state that will survive the units arriving on site weeks later. Ends are sealed against water, because a duct that fills over a wet weekend will ruin a termination that has not been made yet.

  6. 6

    Step 6: Install protection, metering, control and communications

    Protection devices are installed and, where settings apply, loaded from the approved schedule issued by the designer rather than from a default or a previous project, with every setting checked against that schedule by somebody other than the person who applied it. Metering is installed to the arrangement the distribution network operator and the client's billing require. The load management and control equipment is installed and its cabling run with the segregation and resilience the design specifies, and every control and monitoring point is wired to the circuit it is meant to represent. Connectivity for the site is established and proved at this stage - signal strength checked in the actual plant positions rather than assumed, and a wired path provided where the design calls for one.

  7. 7

    Step 7: Carry out dead testing across the installation

    The whole installation is inspected and tested while it is safely de-energised. That covers the checks the designer and the operator require across the cabling, the earthing, the protection and the functional wiring, carried out with calibrated instruments whose certificates are current, and recorded on the test sheets as the results are taken. The specific tests, the sequence and the values that constitute a pass all come from the designer and from the operator, and none of it is decided on site. Anything that fails is put right and retested rather than noted and moved past. These records are the evidence the operator and the client rely on when deciding whether the site may be connected, so they are assembled as a coherent pack rather than as a pile of sheets in a van.

  8. 8

    Step 8: Complete labelling, records and the pre-energisation review

    The installation is walked and reviewed as a whole before energisation is discussed. Labelling complete and matching the drawings, covers and barriers fitted, compound secure, access and escape clear, containment finished, temporary works removed, cable routes recorded and test documentation collated. Every deviation from the issued design is captured as an agreed as-built change with the designer's knowledge rather than left in somebody's head. The operating and isolation arrangements are written down so that the people carrying out commissioning inherit a defined, documented installation. Any documentation the distribution network operator requires is submitted in its format and to its timetable, well ahead of the date it is needed, because the operator's programme has no interest in the project's.

Plant & equipment

  • Hiab, small crane or telehandler for setting substations, kiosks, pillars and switchgear
  • Cable drum stands, winches, rollers and pulling equipment sized for the duct runs
  • Calibrated crimping, cutting and torque tooling for terminations, with records taken as work proceeds
  • Jointing and termination kits, with shelter and clean working arrangements where the design requires
  • Insulation, continuity and earth test equipment with current calibration certificates
  • Cable identification and route tracing equipment for proving circuits across a large duct network
  • Thermal imaging cameras for inspection once the installation is loaded
  • Temporary supplies, task lighting and secure storage for a compound that is not yet energised

Quality control & testing

  • The boundary with the distribution network operator confirmed in writing before any installation begins
  • Cable routes, supports, segregation and containment installed as the design shows and recorded before covering
  • Pulling tensions and bend radii kept within the cable manufacturer's stated limits
  • Terminations made by qualified people, tightened with calibrated tooling and individually recorded
  • Every circuit labelled at both ends and entered on a schedule that stays current as work proceeds
  • Protection settings applied from the approved schedule and independently verified by a second person
  • All testing carried out with calibrated instruments and recorded with traceable serial numbers
  • Labelling, phasing and as-built drawings completed and checked before energisation is requested

Safety watchpoints

  • Work on and near the site's existing electrical apparatus carried out under the asset owner's permits and control
  • Work on or adjacent to the distribution network operator's apparatus, which happens under the operator's control and nobody else's
  • Arc flash risk during work on or near switchgear, with the assessment and protective equipment set by the project
  • Clear isolation, lock-off and demarcation while parts of the site are live and parts are still under construction
  • Heavy cable pulls, drum handling and trapping injuries in confined duct and chamber positions
  • Manual handling of switchgear, boards and cable in tight compounds with limited mechanical access
  • Confined space and access risk when working in chambers, ducts, plant rooms and basement car park areas
  • Continued public and vehicle interface, because the site is still trading while the electrical works proceed

Common defects to hunt

  • Circuits mislabelled or unlabelled at the bay end, so units are connected to the wrong way and found at commissioning
  • Loose or poorly made terminations creating hot joints that only show up on a thermal survey after handover
  • Cable damaged during pulling and installed anyway, failing in service once the site is trading
  • Earthing not completed or not proven before covering, leaving a safety system nobody can verify
  • Protection settings applied but never independently checked against the approved schedule
  • Metering not built to what the network operator or the billing arrangement requires, failing its inspection
  • Connectivity assumed rather than proved in the actual plant positions, leaving units that cannot report
  • Test records incomplete or disorganised, forcing whole sections of the installation to be retested before energisation

How long does Electrical Infrastructure take?

Typical duration: Typically 3-8 weeks of installation on a mid-sized scheme, though switchgear lead times and the network operator's outage and witnessing dates usually set the critical path rather than the labour on site..

Related processes

Previous in sequence

02 - Civils & Groundworks

Next in build sequence

04 - Charger Installation