A further, smaller level of distribution is the Buildingbuilding Networknetwork Operatoroperator (BNO), usually a company employed by the building owner, in a large building with many meters, such as a block of private flats. 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. This arrangement is a relatively new development, 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.<ref> http://library.ukpowernetworks.co.uk/library/en/g81/Design_and_Planning/Planning_and_Design/Documents/EDS+08-0118+Multi-Occupied+Building+Supplies.pdf </ref> Unlike a DNO or an IDNO, BNOs are exempted from any registration requirement by schedules 2 and 3 of The Electricity (Class Exemptions from the Requirement for a Licence) Order 2001<ref>{{cite web|url=http://www.legislation.gov.uk/uksi/2001/3270/made|title=The Electricity (Class Exemptions from the Requirement for a Licence) Order 2001|publisher=}}</ref>
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.
