Check our list of frequently asked questions (FAQs):
- What is a CT Chamber?
- What is a BNO – Building Network Operator?
- What does the BNO standard mean for my project and BNO installation?
- When & why was the BNO process introduced?
- What do the BNO networks changes mean?
- What is the high-level process for a Building Network Operator and who is responsible for which part of the equipment?
- Who installs what, and where?
- Does the MOp (Meter Operator) need to see a BS7671 test certificate before connecting an isolator adjacent to our main supply?
- How much money can I earn from a BNO network?
- How does a customer know if they are supplied from a BNO network?
- Who are BNOs? Is there somewhere we can see a list of them?
- How can the identity of the BNO, of a particular installation, be determined and what is there to prevent a third party subsequently changing/adding to the BNO installation?
- Should there be an isolator between the UK Power Networks cut out and the commencement of the BNO installation?
- What does MOCOPA stand for?
- What are the MOCOPA requirements?
- What type of isolation point do we need adjacent to the meter?
- How is the isolation point sealed?
- Can a BNO pull the main fuse to isolate the building network for maintenance etc.?
- How do I protect my installation from theft of electricity?
- How are meters checked on a BNO Network?
- Is there uniformity across all DNOs for the BNO process?
- Who is responsible for signing off the installation ready for energisation?
- Licensed and unlicensed BNOs. Which standards should the installation follow?
- Who set out the guidance and if there is a query between different providers, who oversees this?
- What is the timescale to design, sign off, approve and install works associated with a BNO installation?
- How do I get a CT Chamber installed?
- How do I know what type of CT Chamber I need?
- What is a 'CT ratio'?
- What physical space is required to accommodate a CT Chamber?
- What is the minimum electrical installation for a CT Chamber installation?
What is a CT Chamber?
In order to measure & invoice electricity consumed by a particular supply and installation, appropriate metering needs to be installed.
If the supply is TP&N (triple pole/ 3-phase & neutral) and rated at 200A and above, the electricity meter works in combination with Current Transformers (CTs). The CTs are usually provided by the energy supplier, but a sealable, tamper-proof, all-insulated chamber (known as the CT chamber) is also required to house the CTs. Some suppliers will provide a CT chamber, but others require the installer to provide the chamber.
Some suppliers have specific requirements for CT chambers on their meter installations.
What is a BNO – Building Network Operator?
A Building Network Operator (BNO) is defined as “an organisation that owns or operates the electricity distribution network within a multiple occupancy building between the intake position and the customer installation.”
The Distribution Network Operator (DNO’s) responsibility ends at the cut-out/ intake position. From this point onwards the BNO manages the installation of the distribution board and cables between that and the individual properties. Please note that only the DNO can terminate your wiring from the first point of isolation to the cut-out / intake position.
What does the BNO standard mean for my project and BNO installation?
The DNO will no longer take responsibility for risers and laterals within multi-occupied buildings. This means that the electrical contractor has to take responsibility for installing the internal electrical connections. This includes CT Panels, wiring and P283.
When & why was the BNO process introduced?
The Electricity Act 1989 allows for electricity companies that meet certain criteria to be exempt from having a distribution licence, whilst the Electricity (Class Exemptions from the Requirement for a License) Order (2001) provided limits on who can qualify to be a licensed exempt distribution network operator.
The publication of the Electricity and Gas Internal Markets Regulations (2011) provided direct to market supply metering for embedded tenants of a building.
In response to this legislative framework the Energy Networks Association produced the Engineering Recommendation G87 (LV Supplies to Multi-Occupied Buildings) national standard to provide guidance for multi-occupied buildings, which defined a Building Network Operator as:
- The organisation that owns or operates the electricity distribution network within a multiple occupancy building, between the intake position and customers installations.
The BNO may be the DNO, another licensed distributor or a third party exempt from an electricity distribution licence (e.g. a facilities management company).
Therefore the building network operator could be the building owner or a body appointed by the building owner to run the electricity services within a building. This clarified the national position and has since become a category B condition of the Distribution Licence for each Licensed Distribution Network Operator (all DNOs and IDNOs).
What do the BNO networks changes mean?
The current national position provides a common framework for the responsibilities and liabilities of each party involved in a multi-occupied building;
- allowing direct access to metering for customers,
- providing clarity on how the Electricity Safety, Quality and Continuity Regulations 2002(ESQCR) apply to all network operators between distribution and supply points;
- provides a basis for common working across the UK
Primarily, the framework describes two states of building network operator:
- a licensed network operator and
- a licence exempt network operator
A building network operator is either one or the other, the framework provides no exceptions. The licensed or unlicensed party owning a building network may claim DUoS (Distribution Use of System) payments for the operation of the building network.
Likewise, the owning party must maintain the building in accordance with the ESQCRs, though the design regulations governing each party differ; a licensed party is bound by the national network operator’s approvals for cable selection, network design etc. whilst the unlicensed party within a building is only constrained by the IET wiring regulations BS7671 (currently 17th edition) and so can provide a cost-effective solution more appropriate to the building.
What is the high-level process for a Building Network Operator and who is responsible for which part of the equipment?
There are three parties involved in any BNO arrangement with each owner being responsible for their network equipment:
- DNO – For a new building the DNO responsibility ends at the customer side of the intake be it a cut out supply, the feeder way on an LV board or the cable end box of an HV or EHV supply.
- BNO – Owns everything beyond the DNO point of demarcation EXCEPT any meters embedded within the BNO network or attached to DNO equipment, these act as islands of ownership within each network. The BNO has the additional responsibility of the building and the infrastructure of the building.
- Electricity Supplier – Owns the meters embedded within the BNO Network
Who installs what, and where?
Depending upon the voltage of the building supply, the DNO requires the provision of either a switch room or a substation within which all DNO supply equipment is installed by the DNO. The switch room is provided by the building owner.
Suppliers and their meter operator representatives will require metering positions at agreed locations within the building. Metering equipment will be installed by the supplier’s appointed meter operators. The supplier’s appointed meter operator will verify the sanctity and security of the building network before energising supplies within the building.
Customer cables may be terminated onto DNO equipment by either the supplier appointed meter operator or by the DNO themselves, depending on the voltage of the supply.
All customer cables are installed by the building network owner (either the building owner themselves or a suitable electrical contractor), noting that meter operators require a point of isolation immediately adjoining the metering positions and that all wiring must be in accordance with BS7671.
Does the MOp (Meter Operator) need to see a BS7671 test certificate before connecting an isolator adjacent to our main supply?
The majority of MOps would like to have access to the BS7671 test Certificate upon request and/or it should be available for reference with the installation.
How much money can I earn from a BNO network?
Contact us to talk about the extent of your network and your load that will enable us to calculate your income via the DUoS process.
How does a customer know if they are supplied from a BNO network?
The customer may not know. In the event of a fault they should contact their DNO using the common ‘105’ call number. The DNO will act accordingly and where ownership is unclear the DNO will attend site to investigate. In the event that the DNO is not the BNO then this is likely to be the building landlord, owner or a maintenance company acting on their behalf. We can help you in this situation.
Who are BNOs? Is there somewhere we can see a list of them?
A BNO can be a building owner, operator or an organisation appointed by the building owner or operator to act on their behalf. There is not one reference point or ’list’ of BNOs.
How can the identity of the BNO, of a particular installation, be determined and what is there to prevent a third party subsequently changing/adding to the BNO installation?
There are a number of methods that are used to confirm the DNO/BNO Boundary
- EDS08-0118 requires the labelling of all DNO owned equipment with an indication of the boundary of ownership.
- All multi-occupied buildings designed since 1st June 2013 will be a building network owned and operated by the building owner.
- Guidance is available on request for properties designed and built before 1st June 2013.
- Since 1st June 2013 DNO ownership ends at the outgoing terminals of the supply termination (be that cut out, LV board, HV supply, EHV supply or boundary metering unit at any voltage).
- Third parties may only operate on a BNO network with the express permission of or appointment by the building network operator.
Should there be an isolator between the UK Power Networks cut out and the commencement of the BNO installation?
Some DNOs recommend the use of an isolator between their intake and the first asset on the BNO network. There is no requirement to install any device as the intake may be used to provide isolation on request for the entire building network but, as this incurs a fee from the Distribution Network Operator for each visit, the DNO considers an isolator to be more cost effective and recommends that an isolator approved under BS 7671, be installed.
What are the MOCOPA requirements?
The MOCOPA requirements are an agreement between Electricity Distribution Businesses and Electricity Meter Operators in Great Britain which defines safety, technical and business interface requirements regarding the provision of meter operation services. Further information can be found at https://www.mocopa.org.uk/
What type of isolation point do we need adjacent to the meter?
Typically, these can be Red head fuses or double pole isolators; guidance can be sought from us.
How is the isolation point sealed?
The MOCOPA approved sealing method will be applied by the supplier appointed MOp, at energisation.
Can a BNO pull the main fuse to isolate the building network for maintenance etc.?
No, the DNO will still be required to pull the main fuse as required.
How do I protect my installation from theft of electricity?
The DNO would not police the building network nor would your appointed supplier. Checks would be made at energisation. The building owner has responsibility to remain vigilant for the property they are managing and in the event any suspicion is raised, should seek appropriate advice from an approved electrician, and notify their supplier.
How are meters checked on a BNO Network?
The BNO meter will be checked and readings taken as with any other installed meter.
Is there uniformity across all DNOs for the BNO process?
Generally, yes. All UK DNOs are required to adhere to ENA ER G87 as part of their license condition; therefore, the requirements for earthing and cable selection are consistent. Each DNO does vary on the issue of ownership, broadly speaking most UK DNOs do not own BNO networks since the introduction of ENA ER G87. One DNO actively operates as a BNO under their IDNO service operation.
Who is responsible for signing off the installation ready for energisation?
The Supplier appointed MOp performs the final energisation at the end user point of metering and confirms the security of the BNO network. The DNO performs the energisation of the intake position only and does not necessarily energise the wider building network, for example; if a point of isolation is installed (be that a switch fuse, isolator or even a distribution board), the intake position can be energised far in advance of the building completion. If supplies are direct from the intake with no isolation internally then energisation of the intake will have to wait until all supplies are secured and will likely be performed by either a MOp or in conjunction with a MOp.
Licensed and unlicensed BNOs. Which standards should the installation follow?
All network operators are governed by the ESQCR. Licensed building network operators are governed by national DNO requirements and BS 7671 whilst unlicensed building network operators will be governed by BS 7671 only, within a building environment.
Who set out the guidance and if there is a query between different providers, who oversees this?
This was established at a national level due to legislation. The regulator, OFGEM, oversee and monitor all network operator issues.
What is the timescale to design, sign off, approve and install works associated with a BNO installation?
This remains in line with the existing guaranteed standards of performance appropriate to the voltage level, maximum power requirement and number of exit points requested by the customer.
How do I get a CT Chamber installed?
It’s simple, just call us on 01905 677 868 and we’ll do the rest.
How do I know what type of CT Chamber I need?
If you are not sure which type of CT installation you need, the size of your incoming supply, or CT ratio – just give us a call and our dedicated team will help guide you through each step of the process.
What is a 'CT ratio'?
A CT ratio refers to the primary and secondary ratings of the coil transfer – number of turns – around the physical conductor. Generally, your Meter Operator will seek this information in order to program your meter for accurate consumption/usage measurement.
An incorrect ratio is likely to cause inaccurate billing of your energy usage. CT ratio is dictated by the physical CTs. Some working examples of CT ratios are:
200A (Amp) LV (Low Voltage) – 200:5; 400A LV – 400:5 and so on.
This information will be provided to you as part of the installation process.
What physical space is required to accommodate a CT Chamber?
It depends who will inherit the installed CT Chamber and CTs after installation – which could be either the BNO, IDNO, or DNO – as to which manufacturer and specification is required for the installed CT Chamber cabinet.
Generally, IDNOs and DNOs have their preferred manufacturer and specification, whereas there is greater flexibility on BNO installation. For example –
- UKPN specify either combined service head & CT Chamber or individual Ritherdon units.
Dimensions of UKPN specified Ritherdon unit is 535 mm wide x 745 mm high x 300 mm deep.
- If no specification has been determined by the inheriting party, you are free to opt for an alternative. Our own non-branded/generic unit, manufactured in-house is a more cost effective and physically smaller unit.
Dimensions of ECS BNO Metering Panel is 480 mm wide x 580 mm high x 215 mm deep.
What is the minimum electrical installation for a CT Chamber installation?
The minimum electrical installation required for a CT Chamber installation is a 4-pole isolator/switch fuse with supporting correctly rated colour coded ‘metering tails’.
Whilst it is possible to arrange installation of a CT Chamber prior to installation of the incoming supply, it is good practice for the CT chamber to follow on once the incoming supply and service head are in place.
