CT (Current Transformer) metering is required to be installed on power supplies with anticipated loads greater than 100Amps/ 70kVA

The supply requires a CT Chamber, cut-out and wiring to the CT metering point.

Under BNO standards that have been introduced since 2013, Building Network Operators (of multi-occupied buildings) are now responsible for CT equipment – namely CT chamber, cabinet and internal wiring.

While the DNO (Distribution Network Operator) was previously responsible for these – they are now only responsible for the metering element.

This has caused BNOs to find themselves responsible for parts of the CT installation, and this is the case across most of the UK now [see diagram below for colour coded key to responsibilities within BNO Networks]. If your site is located within the London region of UKPN, you are also responsible for carrying out the installation of the CT Chambers.

The distinction between BNO and DNO areas of responsibility needs to be made at the outset of your project.

This will ensure you get a managed, co-ordinated and compliant installation every time.

Example of CT Chamber installation


We offer two grades of CT Chambers – depending on your project’s requirements:

  • UKPN for installations to be adopted by UKPN (typically single service to a single metering point, sole tenant premises)
  • ECS brand CT – fully certified to MOCOPA standards, for installation in BNO Network.