Building network operator (BNO): what it is and who uses one

A building network operator (BNO) is the party that owns and runs the private electrical network inside a multi-occupancy building or development. In the UK, its responsibility begins at the intake, the point where the supply from the distribution network operator (DNO) or independent distribution network operator (IDNO) ends, and it runs through the risers, distribution boards and cabling to each unit's meter or consumer unit. The DNO or IDNO looks after the public network up to that boundary. The BNO looks after everything downstream of it.

Who can be a building network operator

A BNO is not always a specialist utility. SSEN describes two types. A licensed BNO holds a distribution licence under the Electricity Act 1989, which makes it an IDNO. An unlicensed BNO holds no licence but still manages the internal network. In practice the unlicensed role is usually filled by the building owner, a landlord, the developer or a facilities management company acting on their behalf.

The reason the role exists is that a DNO will not normally install and maintain cables inside a building with several occupiers. Access for safety checks, maintenance and fault repair is the main concern. So the DNO provides one supply to the building, and someone else takes responsibility for the network beyond it.

Where the BNO's responsibility starts and stops

The DNO typically provides a single, non-metered supply to an agreed intake position, often a main cut-out. From that point the BNO is responsible for the design, installation and maintenance of the internal network. Typical duties include:

• Providing a completion certificate for the internal work before the supply can be energized.
• Signing a technical agreement with the DNO that sets out the BNO's obligations.
• Supplying emergency contact details.
• Installing and managing current transformer (CT) metering on larger supplies. SSEN sets this above 69kVA.

If the BNO's network is adopted by an IDNO, the IDNO takes on future maintenance and repair of the adopted assets, so the building owner no longer carries that cost. Beyond the unit's meter, the installation belongs to the occupier.

Why contractors need to identify the BNO before quoting

Anyone wiring, metering or adding solar to a multi-occupancy site is working on the BNO's network, not just the customer's. That has three practical effects on a quote.

First, approval. The BNO, or its managing agent, may need to approve the work, review the design and receive the completion certificate. Build that sign-off into the programme and price. A step in your own approval workflow, such as the one in Approvals, makes it visible that the quote cannot be released until the BNO has confirmed access and scope.

Second, the end customer. The person who signs the quote may be a tenant, while the party that owns the cables you are touching is the landlord or the facilities company. Be clear on who is paying and who is authorizing.

Third, scope. Adding solar, EV charging or sub-metering changes load on the shared network, so the BNO needs to confirm capacity and any notification duties. Assumptions about this belong in the written scope of your quotes.

This applies across construction trades, lighting installers working on communal areas, and renewables contractors fitting generation or charging on shared buildings.

Related terms

A BNO sits downstream of the DNO and the IDNO. Both operate regulated distribution networks, while an unlicensed BNO operates a private one inside a single building or site.