Distribution network operator
DNO
The company that owns and runs the local electricity network that a property's supply comes from. It isn't the supplier who sends the bill: it deals with power cuts, new connections and supply upgrades. In Great Britain, Ofgem licenses DNOs, each for its own area, and the cut-out and its fuse belong to the DNO. In Northern Ireland, NIE Networks owns and runs the network, regulated by the Utility Regulator.
Using Distribution network operator in context
Reviewed
A distinction worth remembering
The current teaser names the interfaces between sources, loads, controls and protection. The Low-Carbon Electrics part of the electrical course goes further on charge points, heat pumps and the supply, and the electrical foundations are what it builds on.
Questions to take further
- How can I revise Distribution network operator beyond the definition?
- Explain what Distribution network operator describes, compare it with a related term and use it in a topic question. State any assumptions and what evidence you would need before applying the idea to real work.
Sources
- HSE: electrical safety questions — Isolation, competence and precautions before electrical work.
- IET: current BS 7671 edition and updates — BS 7671:2018+A4:2026 and the main subject areas updated by Amendment 4.
- IET: automatic disconnection of supply for island mode prosumer installations — Prosumer installations, island mode, earthing, system referencing and limited fault current from inverters.
- legislation.gov.uk: Electric Vehicles (Smart Charge Points) Regulations 2021 — Which charge points are covered, smart functionality, default charging hours, safety and where the rules extend.
- NIE Networks: generation connections — Northern Ireland's G98/NI and G99/NI connection routes.
- Ofgem: Smart Export Guarantee — Who the Smart Export Guarantee covers in Great Britain and how rates are set.
- GOV.UK: domestic battery energy storage systems — A 2020 government-published review of the safety risks of home batteries.
- legislation.gov.uk: Building Regulations 2010, regulation 12 — In England, the electrical work in a home that has to be notified to building control (a new circuit, a replacement consumer unit, or work on existing circuits in a special location), and what counts as a special location.
- GOV.UK: domestic electrical safety guidance — England guidance on domestic electrical safety; other nations require their own checks.
Where Distribution network operator fits in the learning path
The Low-Carbon Electrics section covers these units:
- EV Charging
- Solar PV and Batteries in Depth
- Heat Pumps, Smart Loads and the Supply
See this section in the full curriculum
This section is on the Plus path. Lesson availability depends on content review and your learning path.
Read, practise, return
1. Read it in context
- Smart, safe and low-carbon homesInstallation
2. Try recalling, then explore practice
Use the memory prompt below to connect the vocabulary.
Follow a topic above to explore how the term is used, then use the learning entry below to find your path.
3. Return to the meaning
After reading or practising, explain the idea in your own words, then check what you remembered.
Recall a related term
Which term fits this definition? Say it to yourself, then reveal it. This is a memory prompt, with no score or saved result.
The assessed greatest simultaneous demand of an installation or part of it. Connected loads, their operating patterns and justified diversity allowances inform the assessment. It helps determine supply and distribution capacity; it is not a guarantee that actual demand can never be higher, and a change of use may require reassessment.
Maximum demand
Read the Maximum demand entryCompare related terms
Open a meaning to compare its role with Distribution network operator, or follow its full entry.
Maximum demand
The assessed greatest simultaneous demand of an installation or part of it. Connected loads, their operating patterns and justified diversity allowances inform the assessment. It helps determine supply and distribution capacity; it is not a guarantee that actual demand can never be higher, and a change of use may require reassessment.
Read the Maximum demand entryTN-C-S — Protective Multiple Earthing (PME)
The most common modern UK supply arrangement: the distributor combines neutral and earth in a single conductor (the PEN) up to the service head, where it splits into separate neutral and earth for the installation. Its weakness is a broken PEN conductor, which can put the whole installation's earthed metalwork at a dangerous voltage — the reason special rules apply to EV charging and other outdoor equipment on PME supplies.
Read the TN-C-S entryG98 — Engineering Recommendation G98
The rules for connecting small, fully type-tested generation of up to 16 A per phase to the public network. It runs in parallel with the low-voltage network, and 16 A per phase works out at 3.68 kW per phase, counting all the plant at the premises. In Great Britain, for a single premises, the installer can usually commission first and then notify the network operator within 28 days. Northern Ireland uses NIE Networks' own version, G98/NI.
Read the G98 entryG99 — Engineering Recommendation G99
The rules for connecting generation or storage to a public distribution network when it doesn't fit G98. That means it runs in parallel with the network and is larger than G98 allows or isn't fully type tested. In Great Britain, you normally apply to the network operator before connecting, though some fast-track categories work differently. Northern Ireland uses NIE Networks' own version, G99/NI.
Read the G99 entryLoad management
A control that knows the total load and turns down or pauses something like an EV charge point, so the whole installation stays within its limit. It can avoid a supply upgrade. Without a system that really limits it, a charger counts at its full rating in the maximum demand, and a customer's habit of charging overnight doesn't change that.
Read the Load management entryA definition is a start. Using it in a real question is where it sticks.