What is a DNO and why does it affect your EV charger installation?

What is a DNO?

A Distribution Network Operator, usually shortened to DNO, is the company that owns and maintains the local electricity network in your area. That network runs from the local substation, along the cables under your street, to the electricity meter fixed to your property.

The DNO does not generate electricity and does not sell you electricity. Electricity generation is handled by power stations and renewable generators. Electricity retail supply is handled by companies such as Octopus Energy or British Gas, who bill you and set your tariff. The DNO sits in between, responsible for the physical infrastructure that delivers electricity to homes and businesses.

This distinction matters because most people assume their energy supplier controls everything related to electricity. In reality, your supplier cannot approve or refuse a new EV charger connection. Only the DNO can do that, because only the DNO is responsible for ensuring the local network remains safe and stable.

The six DNOs in Great Britain

In Great Britain there are six licensed DNOs, each operating a defined geographic region under regulation by Ofgem:

• UK Power Networks — London, the South East of England, and the East of England.Homeowners in these regions will often encounter UK Power Networks' EV application process, including its dedicated online portals.Find installers in London →
• Electricity North West — Greater Manchester, Lancashire, and Cumbria.Installations in this region commonly interact with Electricity North West's connection assessment process.Find installers in Manchester →
• Northern Powergrid — The North East of England and parts of Yorkshire.
• National Grid Electricity Distribution — The Midlands, South West England, and South Wales.Despite the name, this is not the same organisation as National Grid's electricity transmission business.
• SP Energy Networks — Central and southern Scotland, Merseyside, and parts of North Wales.
• SSEN Distribution — The Scottish Highlands and islands, and large areas of southern England.

In Northern Ireland, the equivalent role is performed by NIE Networks.

Why does an EV charger require DNO involvement?

A home EV charger represents one of the largest single electrical loads a domestic property is ever likely to connect. A typical 7 kW charger draws more power than an electric shower, an oven, or a kettle — and it does so continuously for several hours.

The local electricity networks serving most UK streets were designed decades ago around very different assumptions. They expected relatively modest, short-duration peaks from cooking and heating appliances, not sustained high loads from multiple houses charging vehicles simultaneously. Electric vehicles represent a step change in demand at street level, even if overall national generation capacity is sufficient.

Under the Electricity Act 1989, DNOs have a statutory duty to develop and maintain an efficient, co-ordinated, and economical system of electricity distribution. That duty is reinforced by the Distribution Connection and Use of System Agreement (DCUSA), which governs how connections are made and how network capacity is managed. In practical terms, a DNO must be satisfied that adding a new EV charger will not cause voltage drop, flicker, or overloading of equipment that supplies neighbouring properties. This assessment is about the shared network, not about whether your fuse box can cope.

Before an EV charger is connected, the installer must declare the additional load to the DNO. Depending on the circumstances, this happens in one of two ways — and understanding the distinction is the most important thing to take from this guide.

G100 notification — most domestic installations

Engineering Recommendation G100, published in 2020, was developed specifically to streamline the connection of domestic EV chargers. Under G100, an OZEV-approved installer can self-certify and connect a compliant smart charger without requiring advance DNO approval, provided the charger includes demand limiting measures (meaning it can reduce its draw if the local network is under stress). The installer notifies the DNO after installation with the technical details.

This is often described loosely as “DNO notification” rather than “DNO approval”. The key point is that the DNO does not make a decision in advance — it is informed, not consulted. The majority of single 7 kW home charger installations proceed this way.

Formal DNO connection applications — larger and more complex installs

When an installation falls outside the G100 framework — because of its size, the number of chargers, or a constrained local network — a formal connection application is required. This is a standard low-voltage demand connection application processed under the DNO’s own connection charging methodology (governed by DCUSA), not a G99 application. Engineering Recommendation G99 is a separate standard that applies specifically to generation equipment — solar PV, battery storage, and similar — connecting to the distribution network. It is not the relevant standard for EV charger demand connections.

A formal DNO connection application is typically required for:

• Commercial or workplace chargers
• Multiple chargers at a single site
• High-capacity domestic installations where the local network needs capacity assessment
• Properties where the installer identifies the existing supply is insufficient
• Situations where the local network is already operating close to its limits

A formal connection application requires active assessment and a decision from the DNO before installation can proceed. When an installer uses the phrase “DNO application”, it is worth asking specifically: “Is this a G100 notification or a formal connection application?” The answer determines your timeline.

When does a DNO application actually delay installation?

Delays occur when the installer cannot rely on G100 notification and must ask the DNO to assess the network in advance. Several common scenarios trigger this.

• Older properties with a 60 or 80-amp single-phase supply. This is common in older housing stock, including Victorian terraces. The installer may flag that the existing service cable or main fuse is undersized and that a service upgrade by the DNO is needed before the charger can be connected. See our guide to EV charger installation in a Victorian terrace for more on this.EV charger installation in a Victorian terrace →
• Rural properties on long, shared service cables. Homes supplied by long cables from a distant transformer can suffer voltage drop, particularly at peak times. The DNO may need to model the effect of an additional 7 kW load before approving the connection.
• Areas with cumulative demand. In some streets, several properties installing chargers in a short period creates a combined load that exceeds what the local transformer was designed to support. In these cases, later applicants may be asked to wait while the network is assessed or reinforced. This is becoming more common in densely populated urban areas.
• Three-phase supply requests. Requests for a three-phase connection — needed for chargers above 7.4 kW — almost always require a formal DNO application. This involves new cabling, new metering arrangements, and sometimes substation work. It is planned engineering work, not a simple approval.
• Properties served by an ageing transformer. Where a DNO identifies that the local transformer is already operating near its limits, it may require reinforcement works before approving additional load.

What happens during a DNO application?

From a homeowner’s perspective, the process usually follows a clear sequence.

• 1
  Site survey. The installer assesses the property: existing supply rating, earthing arrangement, and any local network constraints. Based on this, they determine whether G100 notification or a formal application is required.
• 2
  Application submission. If a formal application is needed, the installer usually submits it on your behalf. Some DNOs allow consumers to apply directly. Many DNOs now use dedicated online portals, such as UK Power Networks' EV-specific systems, which have reduced turnaround times considerably compared to older email-based methods.
• 3
  DNO review. The DNO assesses the application within its published timescale. It may request further information or clarification.
• 4
  Decision. The outcome will be one of three things: approval as requested; approval with conditions (such as a lower maximum demand or mandatory load management); or a requirement for network reinforcement before the charger can connect.
• 5
  Reinforcement quotation. If reinforcement is required, the DNO issues a quotation. Under DCUSA rules, the cost of reinforcement triggered by a new connection ordinarily falls to the applicant, unless the DNO determines the network was already below standard regardless.

As of 2025, most major DNOs have improved their EV processes significantly, with clearer guidance and shorter response times than were common in 2022 and 2023.

What can you do to reduce the risk of delay?

• Choose an experienced installer. Experienced installers know what information each DNO expects and how to present an application clearly. This reduces the back-and-forth queries that extend timescales.
• Start early. If an installer flags that a formal application may be needed, submit it as early as possible. Do not wait until the planned installation day.
• Sort the supply first. If your property has an ageing main fuse, ask the relevant network company or meter operator about a supply upgrade before the charger application is submitted. Resolving this in advance removes one common obstacle.
• Ask the right question during quotation. Ask directly: "Is this a G100 notification or a formal connection application?" A competent installer should answer immediately and explain why. If they cannot, treat that as a warning sign.
• Consider demand management. Smart chargers with demand limiting measures can reduce the declared load to the DNO, which sometimes allows an installation to proceed under G100 notification rather than a formal application. This is a technical decision for the installer, but it is reasonable to ask whether it changes the requirement.

Frequently asked questions

Further reading

• EV charger installation in a Victorian terrace: electrical supply, cable runs, and period property practicalities
• EV charger installation cost UK (2026): a full breakdown
• EV charger installation in a conservation area: a practical guide
• OZEV grant guide: who qualifies and how to claim in 2026
• Ofgem: check which DNO is licensed in your area
• Official OZEV chargepoint grants guidance (gov.uk)
• OZEV-approved EV charger installers in London
• OZEV-approved EV charger installers in Manchester