A distribution network operator (DNO), also known as a distribution system operator (DSO), is the operator of the electric power distribution system which delivers electricity to most end users. Each country may have many local distribution network operators, which are separate from the transmission system operator (responsible for transporting power in bulk around the country).
In France, Enedis, a subsidiary of EDF, distributes approximately 95% of electricity, with the remaining 5% distributed by 160 local electricity and gas distribution companies (entreprises locales de distribution d'électricité et de gaz or ELD).[1]
In Great Britain, distribution network operators are licensed by the Office of Gas and Electricity Markets.
There are fourteen licensed geographically defined areas, based on the former area electricity board boundaries, where the distribution network operator distributes electricity from the transmission grid to homes and businesses. Under the Utilities Act 2000 they are prevented from supplying electricity; this is done by a separate electricity supply company, chosen by the consumer, who makes use of the distribution network.
Distribution network operators are also responsible for allocating the core Meter Point Administration Number used to identify individual supply points in their respective areas, as well as operating and administering a Meter Point Administration System that manages the details relating to each supply point. These systems then populate ECOES (Electricity Central Online Enquiry Service), the central online database of electricity supply points. Their trade association is the Energy Networks Association.
In 1990, the area boards were replaced by regional electricity companies, which were then privatised. The distribution network operators are the successors to the distribution arms of the regional electricity companies. The distribution network operators have a trade association called the Energy Networks Association.
, six company groups hold the fourteen distribution licences:[2]
| GSP Group ID | Area ID | TLF Zone | Area | DNO company | Group | Former area electricity board | MPAS Operator ID | |
|---|---|---|---|---|---|---|---|---|
| _A | 10 | 1 | East England | Eastern Power Networks plc | UK Power Networks | Eastern Electricity | EELC | |
| _B | 11 | 2 | East Midlands | National Grid Electricity Distribution (East Midlands) plc | National Grid Electricity Distribution | East Midlands Electricity | EMEB | |
| _C | 12 | 3 | London | London Power Networks plc | UK Power Networks | London Electricity Board | LOND | |
| _D | 13 | 4 | North Wales, Merseyside and Cheshire | SP Manweb plc | SP Energy Networks | MANWEB | MANW | |
| _E | 14 | 5 | West Midlands | National Grid Electricity Distribution (West Midlands) plc | National Grid Electricity Distribution | Midlands Electricity | MIDE | |
| _F | 15 | 6 | North East England | Northern Powergrid (Northeast) plc | Northern Powergrid | North Eastern Electricity Board | NEEB | |
| _G | 16 | 7 | North West England | Electricity North West Limited | Electricity North West | NORWEB | NORW | |
| _P | 17 | 14 | North Scotland | Scottish Hydro-Electric Power Distribution plc | Scottish and Southern Electricity Networks | North of Scotland Hydro-Electric Board | HYDE | |
| _N | 18 | 13 | South and Central Scotland | SP Distribution plc | SP Energy Networks | South of Scotland Electricity Board | SPOW | |
| _J | 19 | 9 | South East England | South Eastern Power Networks plc | UK Power Networks | Seeboard | SEEB | |
| _H | 20 | 8 | Southern England | Southern Electric Power Distribution plc | Scottish and Southern Electricity Networks | Southern Electric | SOUT | |
| _K | 21 | 10 | South Wales | National Grid Electricity Distribution (South Wales) plc | National Grid Electricity Distribution | SWALEC | SWAE | |
| _L | 22 | 11 | South West England | National Grid Electricity Distribution (South West) plc | National Grid Electricity Distribution | SWEB | SWEB | |
| _M | 23 | 12 | Yorkshire | Northern Powergrid (Yorkshire) plc | Northern Powergrid | Yorkshire Electricity | YELG |
In addition to the distribution network operators noted above who are licensed for a specific geographic area there are also independent distribution network operators (IDNO). IDNOs own and operate electricity distribution networks which will predominantly be network extensions connected to the existing distribution network, e.g. to serve new housing developments.
| Area ID | Name | Licensee | MPAS Operator ID | |
|---|---|---|---|---|
| 24 | Envoy | Independent Power Networks | IPNL | |
| 25 | ESP Electricity | ESP Electricity | LENG | |
| 26 | Last Mile Electricity | Last Mile Electricity | GUCL | |
| 27 | GTC | The Electricity Network Company Ltd | ETCL | |
| 28 | EDF IDNO | UK Power Networks (IDNO) Ltd | EDFI | |
| 29 | Harlaxton Energy Networks Ltd | Harlaxton (IDNO) | HARL | |
| 30 | Leep Electricity Networks Ltd | Leep Electricity Networks (IDNO) | PENL | |
| 31 | UK Power Distribution Ltd | UK Power Distribution Ltd | UKPD | |
| 32 | Energy Assets Networks Ltd | Energy Assets Networks Ltd. | UDNL | |
| 33 | Eclipse Power Networks | Eclipse Power Networks | GGEN | |
| 34 | mua Electricity Ltd | mua Electricity Ltd | MPDL | |
| 35 | Fulcrum Electricity Assets | Fulcrum Electricity Assets | FEAL | |
| 36 | Vattenfall Networks Ltd | Vattenfall Networks Ltd | VATT | |
| 37 | Optimal Power Networks | Optimal Power Networks | FORB | |
| 38 | Indigo Power Limited | Indigo Power Limited | INDI | |
| 39 | Squire Energy Metering Ltd | Squire Energy Metering Ltd | STRK | |
| 40 | Utility Assets Limited | Utility Assets Limited | UTAL | |
| 42 | Advanced Electricity Networks | Advanced Electricity Networks | AENL | |
| 43 | IDCS Ltd | IDCS Ltd | IDCS |
In this case, the DNO may act as BNO and its responsibility may include the sub-mains to the individual flats, or DNO responsibility may end at the first incomer, in which case the independent BNO is responsible for the secure distribution cabling 'laterals' between that point and the individual fuses and meters.
Historically such cabling would have been maintained and sealed by electricity boards that preceded the DNOs, and different DNOs supplying buildings of different sizes and conditions, may choose to adopt the wiring in the building or to insist that an independent BNO is appointed.[3] Unlike a DNO or an IDNO, BNOs may be exempted from any licensing requirement by schedules 2 and 3 of The Electricity (Class Exemptions from the Requirement for a Licence) Order 2001[4] and this allows those responsible for the building network (such as a housing association) to employ any suitable electrical contractor on an ad-hoc basis.
In Canada, the distribution network operators are known as local distribution companies (LDC).
LDCs normally buy their power from larger companies, sometimes ones dedicated solely to wholesale supply. They re-sell it to the smaller customer. Larger customers typically buy their power directly from the wholesaler, and do not use the LDC.