The period to accept the connection offer from the DNO (usually around 30–90 days). Capacity is not guaranteed until payment is received and may be allocated to another applicant if not accepted in time.
Glossary of terms for Distribution Network Operators
Glossary of terms
This glossary is designed to support developers, planners, and stakeholders engaging with electricity distribution networks in Great Britain. It defines key terms used in the connection process, infrastructure planning, and regulatory context.
Use it to better understand DNO communications, applications, and technical requirements.
This glossary supports the DNO Toolkit and Frequently Asked Questions. All definitions are based on publicly available guidance from Salix and its programme materials as of July 2025.
Application and planning
DNO forms or applications used to either:
- Modify an existing supply (e.g. for additional equipment), or
- Request a completely new supply for a new building or site.
A formal document issued by a DNO outlining required works, costs, and timelines for a new or upgraded electricity connection. It becomes binding once payment is made.
A formal submission to a DNO requesting a new or upgraded electricity connection, used to assess capacity and infrastructure needs.
A rough indication of potential costs. It is not binding and is usually based on early-stage project information.
An assessment to determine whether a proposed energy connection or upgrade is technically and economically viable.
A detailed cost estimate provided after a formal application, required to secure the works.
Informal meetings or surgeries offered by some DNOs to support early engagement. These can clarify network capacity, timelines, and expected costs before a formal application.
Technical infrastructure
The maximum amount of electrical power your site can draw. It’s set in agreement with the DNO and determines standing charges. Can be adjusted if your site’s usage changes.
The maximum electricity output of a generator or the maximum load a grid connection can carry.
The physical linking of infrastructure to enable energy transfer between the DNO and the customer.
The capacity already available at the address in question.
The amount of electrical power used by your site or equipment. Projects that change this load, especially increases, may require DNO approval.
The main fuse protects your supply cables. If your fuse rating exceeds your cable’s capacity, the DNO may recommend changes to avoid safety risks.
The amount of electrical power being used or required at a given time.
Indicates that no additional works are needed because the substation already has the capacity for the increased demand.
The total capacity needed after an upgrade.
Devices that change voltage levels, typically reducing high transmission voltages to lower levels for homes and businesses.
Works and responsibilities
Elements of the connection work that can be undertaken by either the DNO or an IDNO.
Work that must be completed by the DNO or their appointed agents (e.g. ICPs), such as connecting to the substation.
Network operators and bodies
A licensed company that distributes electricity in a specific region of Great Britain. DNOs own and operate the infrastructure from the transmission network to homes and businesses.
An accredited company that can build electricity networks to the standards required for ownership by DNOs or IDNOs.
A licensed company that owns and operates local electricity networks connected to the main distribution network.
The regulator for electricity and gas markets in Great Britain. DNOs are regulated by Ofgem.
A not-for-profit body representing companies that operate energy networks in the UK and Ireland. Maintains an approved appliances database and supports customer connections.
Network infrastructure
Small-scale technologies that generate and store electricity near where it will be used.
Infrastructure that takes electricity from the transmission network and smaller generators and delivers it to homes and businesses at low voltage.
The high-voltage transmission network that moves electricity across long distances before it reaches local distribution networks.
Data related to the historic, current, and future operation, performance, and usage of the electricity network.
A facility that houses equipment like transformers and switchgear, used to step down voltage and manage power flow.
Moves large amounts of electricity over long distances at very high voltages.
Identifiers and codes
A unique number (21 digits) that identifies your electricity supply point. Found on your electricity bill and required for supply changes.
A unique number (up to 12 digits) assigned by local authorities to each land or property in the UK.
