CP1519 ‘Treatment of Low Capacity Connections for Site Specific Line Loss Factor Calculations’

Formal title: Treatment of Low Capacity Connections for Site Specific Line Loss Factor Calculations

Current Status

CPC Consultation
Committee Decision
Awaiting Implementation


Line Loss Factors (LLFs) are calculated and applied to Metered Volumes to account for distribution losses. LLFs are calculated on an individual basis for sites connected at Extra High Voltage (EHV) and on a generic basis for other connections.

There are an increasing number of EHV Sites with a ‘main’ connection and a subordinate small-scale connection. The subordinate connection is often 1 MVA or less and the majority are ancillary import connections for Generating Plant and Apparatus e.g. to power aircraft avoidance lights on wind turbines when the turbine is not Generating its own power. Subordinate connections have low maximum demand and consumption and, if they were single connections in their own right, would be connected at lower voltage levels with generic LLFs.

CP1519 proposes to apply generic losses appropriate to the voltage of connection to sites with a capacity less than 1 MVA. There are already voltage boundary limits to qualify as EHV; this could be extended to applying a capacity boundary (e.g. low capacity sites less than 415V) as a proxy for determining subordinate connections. This would formalise a default replacement process for low consumption sites within Principle 17 of the LLF calculation principles.


CP1519 was raised on 16 July 2019. Progression papers for the Imbalance Settlment Group (ISG) and Settlement Volume Allocation Group (SVG) were presented for information on 23 July and 6 August 2019 respectfully. This allowed the ISG and SVG to provide feedback ahead of consulting as part of the August CPC batch on 12 August 2019.

The CP1519 Consultation was issued 12 August to 6 September 2019. The Assessment Report was presented to the ISG on 17 September 2019 and to the SVG on 8 October 2019. The ISG and SVG both approved CP1519 for implementation on 27 February 2020.

New Podcast

On 12 August we published the consultation on CP1519, stakeholders had until 6 September 2019 to share their views.  The consultation is available in the ‘Documents’ section below.

To help stakeholders with a quick explanation of the issue and details of the consultation, Chris Wood, a senior analyst in the BSC Change team, has recorded a podcast (see the link below). We hope you find this helpful and If you have any feedback on the podcast please get in touch with us at [email protected]

Next Events

CP1519 was implemented on 27 February 2020


Click on the X next to any of the icons to replace them with a short-cut link to the page you are currently on or search for a specific page.