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DNO

What is a Distribution Network Operator (DNO)?

When something goes wrong with the electricity supply to your premises, the first call you’ll probably make is to your supplier. But the people who actually own the cables, substations, and infrastructure between you and the grid aren’t your supplier. They’re your Distribution Network Operator, the DNO. There are 14 of them across Great Britain, each running a regional patch, and which one serves your site is fixed by geography, not by which supplier you happen to use.

DNOs sit between the high-voltage transmission grid and your meter. They don’t sell electricity to you and they don’t appear on your bill as a separate line item, but the cost of running their networks does. Around 15% of a typical business electricity bill goes on distribution charges, recovered from your supplier via the DUoS tariff.

What a DNO actually does

A DNO owns and runs the regional electricity distribution network. That covers everything from the substation where the high-voltage transmission grid steps down to lower voltages, all the way through the local cables, transformers, and connections that bring power into your premises.

If a tree falls on a power line, that’s the DNO’s problem to fix. If a cable fails and a street loses power, the DNO restores it. If your business needs a new connection or an upgrade to a bigger capacity, the DNO is the body that designs the work, quotes for it, and signs it off.

They don’t supply electricity. They don’t bill customers directly. They don’t choose which supplier you use. They run the wires, the substations, and the network management systems behind everything.

The 14 UK DNOs

There are six DNO companies, but they collectively run 14 distribution areas across Great Britain. The split exists because regulated regional monopolies emerged from the old Area Electricity Board structure when the market was privatised in 1990.

The six companies are:

• UK Power Networks. Covers London, the South East, and the East of England (three licence areas).
• Northern Powergrid. Covers Yorkshire and the North East (two licence areas).
• Scottish & Southern Electricity Networks (SSEN). Covers central and southern Scotland and the south of England (two licence areas).
• SP Energy Networks. Covers central Scotland and Merseyside, North Wales, and Cheshire (two licence areas).
• National Grid Electricity Distribution. Covers the Midlands, South West, and South Wales (four licence areas).
• Electricity North West. Covers the North West of England (one licence area).

The first two digits of your MPAN core line identify your distributor. That’s the official, unambiguous way to know which DNO serves your site.

DNO vs supplier vs transporter

Easy to confuse, important to keep separate. Three different roles:

The supplier is who you have a contract with for buying electricity. They send you bills. They handle quotes, renewals, and credit. They appear on your bank statement.

The DNO owns and runs the distribution wires that physically deliver electricity to your meter. They never bill you directly. They recover their costs through your supplier via DUoS charges.

The transmission operator (currently NESO for system operation, plus three regional transmission owners) runs the high-voltage backbone of the grid. They sit above the DNO in the supply chain.

On the gas side, the equivalent of a DNO is the gas transporter, and the equivalent settlement role is held by Xoserve.

How DNO costs reach your bill

DNOs don’t bill you directly. They charge your supplier through the Distribution Use of System tariff, the DUoS charge. Your supplier then bakes that into your unit rate or breaks it out as a separate line on your bill, depending on whether you’re on a fixed rate or pass-through contract.

For most non-half-hourly small business sites, DUoS is invisible. Wrapped into the headline unit rate. For larger half-hourly sites it’s typically passed through directly, with different rates for red, amber, and green time bands across the day.

Distribution charges typically work out at around 18–22% of a small business electricity bill, but the proportion varies significantly by region and time of use. Sites in densely-populated areas tend to face lower distribution costs per unit than rural sites.

DNOs and new connections

If your business needs a new electricity connection. Fitting out a new unit, opening a new site, installing EV chargers, adding solar. Your DNO is the first port of call. The meter installation and new connections process is run by them.

The DNO will assess what capacity you need, what infrastructure is available, and what work is required. If the local network has spare capacity, the quote tends to be modest. If they have to dig up roads, reinforce substations, or run new cables, costs can climb into six figures.

For higher-capacity sites, the connection process also sets your Authorised Supply Capacity (ASC). Get it wrong and you’ll either be paying for headroom you don’t need or face excess capacity charges if you exceed it.

DNO to DSO transition

The role is gradually shifting. The classic DNO ran a one-way network. Power flowed from the transmission grid down to consumers. As more on-site solar, battery storage, and EV charging come on stream, networks need to balance flows actively in both directions and at much shorter notice.

That shift is the move from DNO (passive distribution) to DSO (Distribution System Operator, active management). All six UK DNO groups are running DSO transition programmes, and Ofgem’s RIIO-ED2 price control settlement (running 2023–2028) includes investment to fund this.

For most businesses the practical impact is invisible. For sites with on-site generation or storage, DSO functions matter. They’re how flexibility services get procured and how export limits get managed.

When to call your DNO

A few scenarios where the DNO is the right port of call, not your supplier:

• Power cut. Call 105 from any phone in Great Britain. It connects you to your local DNO’s outage line.
• Damaged power lines, fallen cables, or safety issues. Call 105.
• New connection or capacity upgrade. Contact the DNO direct (their websites list connection enquiry forms).
• Export connection for solar, storage, or generation. The DNO assesses and approves.
• Network reliability or voltage complaints. Goes to the DNO, not your supplier.

For billing, quotes, contract issues, or anything tied to the cost of electricity rather than the wires that deliver it, your supplier is the right call. The DNO can’t help with rates because the DNO doesn’t set them.

Finding your DNO

The most reliable way is the first two digits of your MPAN core line. They identify your distributor under the official industry code list:

• 10. Eastern (UK Power Networks)
• 11. East Midlands (National Grid Electricity Distribution)
• 12. London (UK Power Networks)
• 13. Merseyside, North Wales & Cheshire (SP Energy Networks)
• 14. Midlands (National Grid Electricity Distribution)
• 15. Northern (Northern Powergrid)
• 16. North West (Electricity North West)
• 17. Northern Scotland (SSEN)
• 18. Southern Scotland (SP Energy Networks)
• 19. South East (UK Power Networks)
• 20. Southern (SSEN)
• 21. South Wales (National Grid Electricity Distribution)
• 22. South West (National Grid Electricity Distribution)
• 23. Yorkshire (Northern Powergrid)

Alternatively, the Energy Networks Association runs a postcode lookup at energynetworks.org/customers/find-my-network-operator. Either method gives the right answer.

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